Biological studies of transgender identity: A critical review

References

• Arnold, A. P. (2009). The organizational–activational hypothesis as the foundation for a unified theory of sexual differentiation of all mammalian tissues. Hormones and Behavior, 55(5), 570–578. https://doi.org/10.1016/j.yhbeh.2009.03.011
   PubMed Web of Science ®Google Scholar
• Arnold, A. P. (2020). Sexual differentiation of brain and other tissues: Five questions for the next 50 years. Hormones and Behavior, 120, 104691–104691. https://doi.org/10.1016/j.yhbeh.2020.104691
   PubMed Web of Science ®Google Scholar
• Au Yeung, L., & Tse, W. S. (2017). Why does digit ratio research fail to give any implication regarding the organizational effect of prenatal androgen? Journal of Individual Differences, 38(1), 36–45. https://doi.org/10.1027/1614-0001/a000220
   Web of Science ®Google Scholar
• Auer, M. K., Fuss, J., Stalla, G. K., & Athanasoulia, A. P. (2013). Twenty years of endocrinologic treatment in transsexualism: Analyzing the role of chromosomal analysis and hormonal profiling in the diagnostic work-up. Fertility and Sterility, 100(4), 1103–1110. https://doi.org/10.1016/j.fertnstert.2013.05.047
   PubMed Web of Science ®Google Scholar
• Baldinger-Melich, P., Urquijo Castro, M. F., Seiger, R., Ruef, A., Dwyer, D. B., Kranz, G. S., Klöbl, M., Kambeitz, J., Kaufmann, U., Windischberger, C., Kasper, S., Falkai, P., Lanzenberger, R., & Koutsouleris, N. (2020). Sex matters: A multivariate pattern analysis of sex- and gender-related neuroanatomical differences in cis- and transgender individuals using structural magnetic resonance imaging. Cerebral Cortex, 30(3), 1345–1356. https://doi.org/10.1093/cercor/bhz170
   PubMed Web of Science ®Google Scholar
• Beaulieu, C. (2002). The basis of anisotropic water diffusion in the nervous system—A technical review. NMR in Biomedicine, 15(7–8), 435–455. https://doi.org/10.1002/nbm.782
   PubMed Web of Science ®Google Scholar
• Beemyn, G., & Rankin, S. (2011). The lives of transgender people. Columbia University Press.
   Google Scholar
• Benjamin, H. (1966). The transsexual phenomenon. The Julian Press, Inc.
   Google Scholar
• Blanchard, R. (1985). Typology of male-to-female transsexualism. Archives of Sexual Behavior, 14(3), 247–261. https://doi.org/10.1007/BF01542107
   PubMed Web of Science ®Google Scholar
• Bornstein, K. (1998). My gender workbook. Routledge.
   Google Scholar
• Brown, W. M., Hines, M., Fane, B. A., & Breedlove, S. M. (2002). Masculinized finger length patterns in human males and females with congenital adrenal hyperplasia. Hormones and Behavior, 42(4), 380–386. https://doi.org/10.1006/hbeh.2002.1830
   PubMed Web of Science ®Google Scholar
• Burke, S. M., Kreukels, B. P. C., Cohen-Kettenis, P. T., Veltman, D. J., Klink, D. T., & Bakker, J. (2016). Male-typical visuospatial functioning in gynephilic girls with gender dysphoria—Organizational and activational effects of testosterone. Journal of Psychiatry & Neuroscience: JPN, 41(6), 395–404. https://doi.org/10.1503/jpn.150147
   PubMed Web of Science ®Google Scholar
• Burke, S. M., Manzouri, A. H., Dhejne, C., Bergström, K., Arver, S., Feusner, J. D., & Savic-Berglund, I. (2018). Testosterone effects on the brain in transgender men. Cerebral Cortex (New York, N.Y.: 1991), 28(5), 1582–1596. https://doi.org/10.1093/cercor/bhx054
   PubMed Web of Science ®Google Scholar
• Carrillo, B., Gómez-Gil, E., Rametti, G., Junque, C., Gomez, Á., Karadi, K., Segovia, S., & Guillamon, A. (2010). Cortical activation during mental rotation in male-to-female and female-to-male transsexuals under hormonal treatment. Psychoneuroendocrinology, 35(8), 1213–1222. https://doi.org/10.1016/j.psyneuen.2010.02.010
   PubMed Web of Science ®Google Scholar
• Case, L. K., Brang, D., Landazuri, R., Viswanathan, P., & Ramachandran, V. S. (2017). Altered white matter and sensory response to bodily sensation in female-to-male transgender individuals. Archives of Sexual Behavior, 46(5), 1223–1237. https://doi.org/10.1007/s10508-016-0850-z
   PubMed Web of Science ®Google Scholar
• Clemens, B., Derntl, B., Smith, E., Junger, J., Neulen, J., Mingoia, G., Schneider, F., Abel, T., Bzdok, D., & Habel, U. (2020). Predictive pattern classification can distinguish gender identity subtypes from behavior and brain imaging. Cerebral Cortex (New York, N.Y.: 1991), 30(5), 2755–2765. https://doi.org/10.1093/cercor/bhz272
   PubMed Web of Science ®Google Scholar
• Clemens, B., Junger, J., Pauly, K., Neulen, J., Neuschaefer-Rube, C., Frölich, D., Mingoia, G., Derntl, B., & Habel, U. (2017). Male-to-female gender dysphoria: Gender-specific differences in resting-state networks. Brain and Behavior, 7(5), e00691–e00691. https://doi.org/10.1002/brb3.691
   Web of Science ®Google Scholar
• Cohen-Kettenis, P. T., & Klink, D. (2015). Adolescents with gender dysphoria. Best Practice & Research. Clinical Endocrinology & Metabolism, 29(3), 485–495. https://doi.org/10.1016/j.beem.2015.01.004
   PubMed Web of Science ®Google Scholar
• Cohen-Kettenis, P. T., & Pfäfflin, F. (2010). The DSM diagnostic criteria for gender identity disorder in adolescents and adults. Archives of Sexual Behavior, 39(2), 499–513. https://doi.org/10.1007/s10508-009-9562-y
   PubMed Web of Science ®Google Scholar
• Collins, A. L., Kim, Y., Sklar, P., O’Donovan, M. C., & Sullivan, P. F. (2012). Hypothesis-driven candidate genes for schizophrenia compared to genome-wide association results. Psychological Medicine, 42(3), 607–616. https://doi.org/10.1017/S0033291711001607
   PubMed Web of Science ®Google Scholar
• Coolidge, F. L., Thede, L. L., & Young, S. E. (2002). The heritability of gender identity disorder in a child and adolescent twin sample. Behavior Genetics, 32(4), 251–257. https://doi.org/10.1023/A:1019724712983
   PubMed Web of Science ®Google Scholar
• Cooper, B. (2001). Nature, nurture and mental disorder: Old concepts in the new millennium. The British Journal of Psychiatry. Supplement, 40(S40), s91–s101. https://doi.org/10.1192/bjp.178.40.s91
   PubMedGoogle Scholar
• Cowan, W. M. (1979). The development of the brain. Scientific American, 241(3), 113–133. https://doi.org/10.1038/scientificamerican0979-112
   PubMed Web of Science ®Google Scholar
• de Sanctis, V., Soliman, A. T., Elsedfy, H., Soliman, N., Elalaily, R., & Di Maio, S. (2017). Is the second to fourth digit ratio (2D:4D) a biomarker of sex-steroids activity? Pediatric Endocrinology Reviews: PER, 14(4), 378–386. 10.17458/per.vol14.2017.SSE.SexSteroids[PMC][28613048]
   PubMed Web of Science ®Google Scholar
• Ducharme, S., Albaugh, M. D., Hudziak, J. J., Botteron, K. N., Nguyen, T.-V., Truong, C., Evans, A. C., Karama, S., Ball, W. S., Byars, A. W., Schapiro, M., Bommer, W., Carr, A., German, A., Dunn, S., Rivkin, M. J., Waber, D., Mulkern, R., Vajapeyam, S., … O’Neill, J. (2014). Anxious/depressed symptoms are linked to right ventromedial prefrontal cortical thickness maturation in healthy children and young adults. Cerebral Cortex, 24(11), 2941–2950. https://doi.org/10.1093/cercor/bht151
   PubMed Web of Science ®Google Scholar
• Ecker, A. (1875). Some remarks about a varying character in the hand of humans. Archives Fur Anthropology, 8, 68–74.
   Google Scholar
• Emory, L. E., Williams, D. H., Cole, C. M., Amparo, E. G., & Meyer, W. J. (1991). Anatomic variation of the corpus callosum in persons with gender dysphoria. Archives of Sexual Behavior, 20(4), 409–417. https://doi.org/10.1007/BF01542620
   PubMed Web of Science ®Google Scholar
• Feng, J., Spence, I., & Pratt, J. (2007). Playing an action video game reduces gender differences in spatial cognition. Psychological Science, 18(10), 850–855. https://doi.org/10.1111/j.1467-9280.2007.01990.x
   PubMed Web of Science ®Google Scholar
• Fernández, R., Cortés-Cortés, J., Esteva, I., Gómez-Gil, E., Almaraz, M. C., Lema, E., Rumbo, T., Haro-Mora, J.-J., Roda, E., Guillamón, A., & Pásaro, E. (2015). The CYP17 MspA1 polymorphism and the gender dysphoria. The Journal of Sexual Medicine, 12(6), 1329–1333. https://doi.org/10.1111/jsm.12895
   PubMed Web of Science ®Google Scholar
• Fernández, R., Esteva, I., Gómez-Gil, E., Rumbo, T., Almaraz, M. C., Roda, E., Haro-Mora, J.-J., Guillamón, A., & Pásaro, E. (2014). Association study of ERβ, AR, and CYP19A1 genes and MtF transsexualism. The Journal of Sexual Medicine, 11(12), 2986–2994. https://doi.org/10.1111/jsm.12673
   PubMed Web of Science ®Google Scholar
• Fernández, R., Guillamon, A., Cortés-Cortés, J., Gómez-Gil, E., Jácome, A., Esteva, I., Almaraz, M., Mora, M., Aranda, G., & Pásaro, E. (2018a). Molecular basis of gender dysphoria: Androgen and estrogen receptor interaction. Psychoneuroendocrinology, 98, 161–167. https://doi.org/10.1016/j.psyneuen.2018.07.032
   PubMed Web of Science ®Google Scholar
• Fernández, R., Guillamón, A., Gómez-Gil, E., Esteva, I., Almaraz, M. C., Cortés-Cortés, J., Lamas, B., Lema, E., & Pásaro, E. (2018b). Analyses of karyotype by G-banding and high-resolution microarrays in a gender dysphoria population. Genes & Genomics, 40(5), 465–473. https://doi.org/10.1007/s13258-017-0646-0
   PubMed Web of Science ®Google Scholar
• Fisher, A. D., Ristori, J., Castellini, G., Cocchetti, C., Cassioli, E., Orsolini, S., Sensi, C., Romani, A., Mazzoli, F., Cipriani, A., Ricca, V., Vignozzi, L., Viggiano, M. P., Mascalchi, M., Maggi, M., & Gavazzi, G. (2020). Neural correlates of gender face perception in transgender people. Journal of Clinical Medicine, 9(6), 1731–1731. https://doi.org/10.3390/jcm9061731
   PubMed Web of Science ®Google Scholar
• Flint, C., Förster, K., Koser, S. A., Konrad, C., Zwitserlood, P., Berger, K., Hermesdorf, M., Kircher, T., Nenadic, I., Krug, A., Baune, B. T., Dohm, K., Redlich, R., Opel, N., Arolt, V., Hahn, T., Jiang, X., Dannlowski, U., & Grotegerd, D. (2020). Biological sex classification with structural MRI data shows increased misclassification in transgender women. Neuropsychopharmacology: Official Publication of the American College of Neuropsychopharmacology, 45(10), 1758–1765. https://doi.org/10.1038/s41386-020-0666-3
   PubMed Web of Science ®Google Scholar
• Flores, A. R., Herman, J. L., Gates, G. J., & Brown, T. N. T. (2016). How many adults identify as transgender in the United States? The Williams Institute.
   Google Scholar
• Galis, F., Ten Broek, C. M. A., Van Dongen, S., & Wijnaendts, L. C. D. (2010). Sexual dimorphism in the prenatal digit ratio (2D:4D). Archives of Sexual Behavior, 39(1), 57–62. https://doi.org/10.1007/s10508-009-9485-7
   PubMed Web of Science ®Google Scholar
• Galupo, M. P., Henise, S. B., & Mercer, N. L. (2016). “The labels don’t work very well”: Transgender individuals’ conceptualizations of sexual orientation and sexual identity. International Journal of Transgenderism, 17(2), 93–104. https://doi.org/10.1080/15532739.2016.1189373
   Web of Science ®Google Scholar
• Garcia-Falgueras, A., Ligtenberg, L., Kruijver, F. P. M., & Swaab, D. F. (2011). Galanin neurons in the intermediate nucleus (InM) of the human hypothalamus in relation to sex, age, and gender identity. The Journal of Comparative Neurology, 519(15), 3061–3084. https://doi.org/10.1002/cne.22666
   PubMed Web of Science ®Google Scholar
• Garcia-Falgueras, A., & Swaab, D. F. (2008). A sex difference in the hypothalamic uncinate nucleus: Relationship to gender identity. Brain, 131(12), 3132–3146. https://doi.org/10.1093/brain/awn276
   PubMed Web of Science ®Google Scholar
• Giedd, J. N., Raznahan, A., Mills, K. L., & Lenroot, R. K. (2012). Review: Magnetic resonance imaging of male/female differences in human adolescent brain anatomy. Biology of Sex Differences, 3(1), 19–19. https://doi.org/10.1186/2042-6410-3-19
   PubMed Web of Science ®Google Scholar
• Gómez-Gil, E., Esteva, I., Carrasco, R., Almaraz, M. C., Pasaro, E., Salamero, M., & Guillamon, A. (2011). Birth order and ratio of brothers to sisters in Spanish transsexuals. Archives of Sexual Behavior, 40(3), 505–510. https://doi.org/10.1007/s10508-010-9614-3
   PubMed Web of Science ®Google Scholar
• Hahn, A., Kranz, G. S., Küblböck, M., Kaufmann, U., Ganger, S., Hummer, A., Seiger, R., Spies, M., Winkler, D., Kasper, S., Windischberger, C., Swaab, D. F., & Lanzenberger, R. (2015). Structural connectivity networks of transgender people. Cerebral Cortex (New York, N.Y.: 1991), 25(10), 3527–3534. https://doi.org/10.1093/cercor/bhu194
   PubMed Web of Science ®Google Scholar
• Hampson, E., & Sankar, J. S. (2012). Re-examining the Manning hypothesis: Androgen receptor polymorphism and the 2D:4D digit ratio. Evolution and Human Behavior, 33(5), 557–561. https://doi.org/10.1016/j.evolhumbehav.2012.02.003
   Web of Science ®Google Scholar
• Haraldsen, I. R., Opjordsmoen, S., Egeland, T., & Finset, A. (2003). Sex-sensitive cognitive performance in untreated patients with early onset gender identity disorder. Psychoneuroendocrinology, 28(7), 906–915. https://doi.org/10.1016/S0306-4530(02)00107-5
   PubMed Web of Science ®Google Scholar
• Hare, L., Bernard, P., Sánchez, F. J., Baird, P. N., Vilain, E., Kennedy, T., & Harley, V. R. (2009). Androgen receptor repeat length polymorphism associated with male-to-female transsexualism. Biological Psychiatry, 65(1), 93–96. https://doi.org/10.1016/j.biopsych.2008.08.033
   PubMed Web of Science ®Google Scholar
• Heylens, G., De Cuypere, G., Zucker, K. J., Schelfaut, C., Elaut, E., Vanden Bossche, H., De Baere, E., & T’Sjoen, G. (2012). Gender identity disorder in twins: A review of the case report literature. The Journal of Sexual Medicine, 9(3), 751–757. https://doi.org/10.1111/j.1743-6109.2011.02567.x
   PubMed Web of Science ®Google Scholar
• Hines, M., Constantinescu, M., & Spencer, D. (2015). Early androgen exposure and human gender development. Biology of Sex Differences, 6(1), 3–3. https://doi.org/10.1186/s13293-015-0022-1
   PubMedGoogle Scholar
• Hoekzema, E., Schagen, S. E. E., Kreukels, B. P. C., Veltman, D. J., Cohen-Kettenis, P. T., Delemarre-van de Waal, H., & Bakker, J. (2015). Regional volumes and spatial volumetric distribution of gray matter in the gender dysphoric brain. Psychoneuroendocrinology, 55, 59–71. https://doi.org/10.1016/j.psyneuen.2015.01.016
   PubMed Web of Science ®Google Scholar
• Inoubli, A., De Cuypere, G., Rubens, R., Heylens, G., Elaut, E., Van Caenegem, E., Menten, B., & T’Sjoen, G. (2011). Karyotyping, is it worthwhile in transsexualism? The Journal of Sexual Medicine, 8(2), 475–478. https://doi.org/10.1111/j.1743-6109.2010.02130.x
   PubMed Web of Science ®Google Scholar
• James, S. E., Herman, J. L., Rankin, S., Keisling, M., Mottet, L., & Anafi, M. (2016). The report of the 2015 U.S. transgender survey.
   Google Scholar
• Joel, D., Garcia-Falgueras, A., & Swaab, D. (2020). The complex relationships between sex and the brain. The Neuroscientist, 26(2), 156–169. 10.1177/1073858419867298
   PubMed Web of Science ®Google Scholar
• Karalexi, M. A., Georgakis, M. K., Dimitriou, N. G., Vichos, T., Katsimpris, A., Petridou, E. T., & Papadopoulos, F. C. (2020). Gender-affirming hormone treatment and cognitive function in transgender young adults: A systematic review and meta-analysis. Psychoneuroendocrinology, 119, 104721–104721. https://doi.org/10.1016/j.psyneuen.2020.104721
   PubMed Web of Science ®Google Scholar
• Karstens, A. J., Ajilore, O., Rubin, L. H., Yang, S., Zhang, A., Leow, A., Kumar, A., & Lamar, M. (2017). Investigating the separate and interactive associations of trauma and depression on brain structure: Implications for cognition and aging. International Journal of Geriatric Psychiatry, 32(11), 1190–1199. https://doi.org/10.1002/gps.4755
   PubMed Web of Science ®Google Scholar
• Khorashad, B. S., Manzouri, A., Feusner, J. D., & Savic, I. (2021). Cross-sex hormone treatment and own-body perception: Behavioral and brain connectivity profiles. Scientific Reports, 11(1), 2799–2799. https://doi.org/10.1038/s41598-020-80687-2
   PubMedGoogle Scholar
• Kilpatrick, L. A., Holmberg, M., Manzouri, A., & Savic, I. (2019). Cross sex hormone treatment is linked with a reversal of cerebral patterns associated with gender dysphoria to the baseline of cisgender controls. The European Journal of Neuroscience, 50(8), 3269–3281. https://doi.org/10.1111/ejn.14420
   PubMed Web of Science ®Google Scholar
• Kim, G.-W., Kim, S.-K., & Jeong, G.-W. (2016). Neural activation-based sexual orientation and its correlation with free testosterone level in postoperative female-to-male transsexuals: Preliminary study with 3.0-T fMRI. Surgical and Radiologic Anatomy, 38(2), 245–252. https://doi.org/10.1007/s00276-015-1547-z
   PubMed Web of Science ®Google Scholar
• Kim, T.-H., Kim, G.-W., Kim, S.-K., & Jeong, G.-W. (2016). Brain activation-based sexual orientation in female-to-male transsexuals. International Journal of Impotence Research, 28(1), 31–38. https://doi.org/10.1038/ijir.2015.29
   PubMed Web of Science ®Google Scholar
• Koenecke, A., Nam, A., Lake, E., Nudell, J., Quartey, M., Mengesha, Z., Toups, C., Rickford, J. R., Jurafsky, D., & Goel, S. (2020). Racial disparities in automated speech recognition. Proceedings of the National Academy of Sciences of the United States of America, 117(14), 7684–7689. https://doi.org/10.1073/pnas.1915768117
   PubMed Web of Science ®Google Scholar
• Kraemer, B., Hobi, S., Rufer, M., Hepp, U., Büchi, S., & Schnyder, U. (2010). Partnerschaft und Sexualität von Frau-zu-Mann transsexuellen Männern. Psychotherapie, Psychosomatik, Medizinische Psychologie, 60(1), 25–30. https://doi.org/10.1055/s-0028-1103264
   PubMedGoogle Scholar
• Kranz, G. S., Hahn, A., Kaufmann, U., Kublbock, M., Hummer, A., Ganger, S., Seiger, R., Winkler, D., Swaab, D. F., Windischberger, C., Kasper, S., & Lanzenberger, R. (2014). White matter microstructure in transsexuals and controls investigated by diffusion tensor imaging. The Journal of Neuroscience: The Official Journal of the Society for Neuroscience, 34(46), 15466–15475. https://doi.org/10.1523/JNEUROSCI.2488-14.2014
   PubMed Web of Science ®Google Scholar
• Kruijver, F. P. M., Fernández-Guasti, A., Fodor, M., Kraan, E. M., & Swaab, D. F. (2001). Sex differences in androgen receptors of the human mamillary bodies are related to endocrine status rather than to sexual orientation or transsexuality. The Journal of Clinical Endocrinology and Metabolism, 86(2), 818–827. https://doi.org/10.1210/jcem.86.2.7258
   PubMed Web of Science ®Google Scholar
• Kruijver, F. P. M., Zhou, J.-N., Pool, C. W., Hofman, M. A., Gooren, L. J. G., & Swaab, D. F. (2000). Male-to-female transsexuals have female neuron numbers in a limbic nucleus. The Journal of Clinical Endocrinology & Metabolism, 85(5), 2034–2041. https://doi.org/10.1210/jcem.85.5.6564
   PubMed Web of Science ®Google Scholar
• Ku, H.-L., Lin, C.-S., Chao, H.-T., Tu, P.-C., Li, C.-T., Cheng, C.-M., Su, T.-P., Lee, Y.-C., & Hsieh, J.-C. (2013). Brain signature characterizing the body-brain-mind axis of transsexuals. PloS One, 8(7), e70808–e70808. https://doi.org/10.1371/journal.pone.0070808
   Web of Science ®Google Scholar
• Kuper, L. E., Nussbaum, R., & Mustanski, B. (2011). Exploring the diversity of gender and sexual orientation identities in an online sample of transgender individuals. Journal of Sex Research, 49, 244–254 https://doi.org/10.1080/00224499.2011.596954
   PubMed Web of Science ®Google Scholar
• Leiner, J. E. M., Scherndl, T., & Ortner, T. M. (2018). How do men and women perceive a high-stakes test situation? Frontiers in Psychology, 9, 2216–2216. https://doi.org/10.3389/fpsyg.2018.02216
   PubMed Web of Science ®Google Scholar
• Leinung, M., & Wu, C. (2017). The biologic basis of transgender identity: 2D:4D finger length ratios implicate a role for prenatal androgen activity. Endocrine Practice, 23(6), 669–671. https://doi.org/10.4158/EP161528.OR
   PubMed Web of Science ®Google Scholar
• Lenroot, R. K., Gogtay, N., Greenstein, D. K., Wells, E. M., Wallace, G. L., Clasen, L. S., Blumenthal, J. D., Lerch, J., Zijdenbos, A. P., Evans, A. C., Thompson, P. M., & Giedd, J. N. (2007). Sexual dimorphism of brain developmental trajectories during childhood and adolescence. NeuroImage, 36(4), 1065–1073. https://doi.org/10.1016/j.neuroimage.2007.03.053
   PubMed Web of Science ®Google Scholar
• Leslie, M. (2019). The mismeasure of hands? Science (New York, N.Y.), 364(6444), 923–925. https://doi.org/10.1126/science.364.6444.923
   PubMed Web of Science ®Google Scholar
• Lin, C.-S., Ku, H.-L., Chao, H.-T., Tu, P.-C., Li, C.-T., Cheng, C.-M., Su, T.-P., Lee, Y.-C., & Hsieh, J.-C. (2014). Neural network of body representation differs between transsexuals and cissexuals. PloS One, 9(1), e85914–e85914. https://doi.org/10.1371/journal.pone.0085914
   Web of Science ®Google Scholar
• Lolli, L., Batterham, A. M., Kratochvíl, L., Flegr, J., Weston, K. L., & Atkinson, G. (2017). A comprehensive allometric analysis of 2nd digit length to 4th digit length in humans. Proceedings of the Royal Society B: Biological Sciences, 284(1857), 20170356–20170356. https://doi.org/10.1098/rspb.2017.0356
   PubMed Web of Science ®Google Scholar
• Lombardo, F., Toselli, L., Grassetti, D., Paoli, D., Masciandaro, P., Valentini, F., Lenzi, A., & Gandini, L. (2013). Hormone and genetic study in male to female transsexual patients. Journal of Endocrinological Investigation, 36(8), 550–557. https://doi.org/10.3275/8813[PMC][23324476]
   PubMed Web of Science ®Google Scholar
• Luders, E., Sánchez, F. J., Gaser, C., Toga, A. W., Narr, K. L., Hamilton, L. S., & Vilain, E. (2009). Regional gray matter variation in male-to-female transsexualism. NeuroImage, 46(4), 904–907. https://doi.org/10.1016/j.neuroimage.2009.03.048
   PubMed Web of Science ®Google Scholar
• Lutchmaya, S., Baron-Cohen, S., Raggatt, P., Knickmeyer, R., & Manning, J. T. (2004). 2nd to 4th digit ratios, fetal testosterone and estradiol. Early Human Development, 77(1–2), 23–28. https://doi.org/10.1016/j.earlhumdev.2003.12.002
   PubMed Web of Science ®Google Scholar
• Majid, D. S. A., Burke, S. M., Manzouri, A., Moody, T. D., Dhejne, C., Feusner, J. D., & Savic, I. (2020). Neural systems for own-body processing align with gender identity rather than birth-assigned sex. Cerebral Cortex (New York, N.Y.: 1991), 30(5), 2897–2909. https://doi.org/10.1093/cercor/bhz282
   PubMed Web of Science ®Google Scholar
• Manning, J. T. (2017). Prenatal sex steroids and transgender identity: Is there a link with digit ratio? Endocrine Practice: Official Journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists, 23(6), 738–740. https://doi.org/10.4158/EP171843.CO
   PubMed Web of Science ®Google Scholar
• Manning, J. T., Churchill, A. J. G., & Peters, M. (2007). The effects of sex, ethnicity, and sexual orientation on self-measured digit ratio (2D:4D). Archives of Sexual Behavior, 36(2), 223–233. https://doi.org/10.1007/s10508-007-9171-6
   PubMed Web of Science ®Google Scholar
• Manning, J. T., & Fink, B. (2008). Digit ratio (2D:4D), dominance, reproductive success, asymmetry, and sociosexuality in the BBC Internet Study. American Journal of Human Biology: The Official Journal of the Human Biology Council, 20(4), 451–461. https://doi.org/10.1002/ajhb.20767
   PubMed Web of Science ®Google Scholar
• Manning, J. T., Scutt, D., Wilson, J., & Lewis-Jones, D. I. (1998). The ratio of 2nd to 4th digit length: A predictor of sperm numbers and concentrations of testosterone, ­luteinizing hormone and oestrogen. Human Reproduction (Oxford, England), 13(11), 3000–3004. https://doi.org/10.1093/humrep/13.11.3000
   PubMed Web of Science ®Google Scholar
• Manzouri, A., Kosidou, K., & Savic, I. (2017). Anatomical and functional findings in female-to-male transsexuals: Testing a new hypothesis. Cerebral Cortex, 27(2), 998–1010. https://doi.org/10.1093/cercor/bhv278
   PubMed Web of Science ®Google Scholar
• Manzouri, A., & Savic, I. (2019). Possible neurobiological underpinnings of homosexuality and gender dysphoria. Cerebral Cortex (New York, N.Y.: 1991), 29(5), 2084–2101. https://doi.org/10.1093/cercor/bhy090
   PubMed Web of Science ®Google Scholar
• Matsuno, E., & Budge, S. L. (2017). Non-binary/genderqueer identities: A critical review of the literature. Current Sexual Health Reports, 9(3), 116–120. 10.1007/s11930-017-0111-8
   Google Scholar
• Moser, C. (2010). Blanchard’s autogynephilia theory: A critique. Journal of Homosexuality, 57(6), 790–809. https://doi.org/10.1080/00918369.2010.486241
   PubMed Web of Science ®Google Scholar
• Mueller, S. C., Landré, L., Wierckx, K., & T’Sjoen, G. (2017). A structural magnetic resonance imaging study in transgender persons on cross-sex hormone therapy. Neuroendocrinology, 105(2), 123–130. https://doi.org/10.1159/000448787
   PubMed Web of Science ®Google Scholar
• Mueller, S. C., Wierckx, K., Jackson, K., & T’Sjoen, G. (2016). Circulating androgens correlate with resting-state MRI in transgender men. Psychoneuroendocrinology, 73, 91–98. https://doi.org/10.1016/j.psyneuen.2016.07.212
   PubMed Web of Science ®Google Scholar
• Nota, N. M., Burke, S. M., den Heijer, M., Soleman, R. S., Lambalk, C. B., Cohen-Kettenis, P. T., Veltman, D. J., & Kreukels, B. P. (2017a). Brain sexual differentiation and effects of cross-sex hormone therapy in transpeople: A resting-state functional magnetic resonance study. Neurophysiologie Clinique = Clinical Neurophysiology, 47(5-6), 361–370. https://doi.org/10.1016/j.neucli.2017.09.001
   PubMed Web of Science ®Google Scholar
• Nota, N. M., Kreukels, B. P. C., den Heijer, M., Veltman, D. J., Cohen-Kettenis, P. T., Burke, S. M., & Bakker, J. (2017b). Brain functional connectivity patterns in children and adolescents with gender dysphoria: Sex-atypical or not? Psychoneuroendocrinology, 86, 187–195. https://doi.org/10.1016/j.psyneuen.2017.09.014
   PubMed Web of Science ®Google Scholar
• Pauly, I. (1998). Current concepts in transgender identity (p. 248), D. Denny (Ed.). Garland Publishing, Inc.
   Google Scholar
• Peters, M., Lehmann, W., Takahira, S., Takeuchi, Y., & Jordan, K. (2006). Mental rotation test performance in four cross-cultural samples (n = 3367): Overall sex differences and the role of academic program in performance. Cortex; A Journal Devoted to the Study of the Nervous System and Behavior, 42(7), 1005–1014. https://doi.org/10.1016/S0010-9452(08)70206-5
   PubMed Web of Science ®Google Scholar
• Phoenix, C. H., Goy, R. W., Gerall, A. A., & Young, W. C. (1959). Organizing action of prenatally administered testosterone propionate on the tissues mediating behavior in the female guinea pig. Endocrinology, 65(3), 369–382. https://doi.org/10.1210/endo-65-3-369
   PubMed Web of Science ®Google Scholar
• Puckett, J. A., Glozier, K., Kimball, D., Giffel, R. (2021). A systematic review of sexuality measurement in transgender and gender diverse populations. Psychology of Sexual Orientation and Gender Diversity, 8(3), 276–291. https://doi.org/10.1037/sgd0000523
   Google Scholar
• Puts, D. A., McDaniel, M. A., Jordan, C. L., & Breedlove, S. M. (2008). Spatial ability and prenatal androgens: Meta-analyses of congenital adrenal hyperplasia and digit ratio (2D:4D) studies. Archives of Sexual Behavior, 37(1), 100–111. https://doi.org/10.1007/s10508-007-9271-3
   PubMed Web of Science ®Google Scholar
• Rametti, G., Carrillo, B., Gómez-Gil, E., Junque, C., Segovia, S., Gomez, Á., & Guillamon, A. (2011). White matter microstructure in female to male transsexuals before cross-sex hormonal treatment. A diffusion tensor imaging study. Journal of Psychiatric Research, 45(2), 199–204. https://doi.org/10.1016/j.jpsychires.2010.05.006
   PubMed Web of Science ®Google Scholar
• Rametti, G., Carrillo, B., Gómez-Gil, E., Junque, C., Zubiarre-Elorza, L., Segovia, S., Gomez, Á., & Guillamon, A. (2011). The microstructure of white matter in male to female transsexuals before cross-sex hormonal treatment. A DTI study. Journal of Psychiatric Research, 45(7), 949–954. https://doi.org/10.1016/j.jpsychires.2010.11.007
   PubMed Web of Science ®Google Scholar
• Reisner, S. L., Deutsch, M. B., Bhasin, S., Bockting, W., Brown, G. R., Feldman, J., Garofalo, R., Kreukels, B., Radix, A., Safer, J. D., Tangpricha, V., TʼSjoen, G., & Goodman, M. (2016). Advancing methods for US transgender health research. Current Opinion in Endocrinology, Diabetes, and Obesity, 23(2), 198–207. https://doi.org/10.1097/MED.0000000000000229
   PubMed Web of Science ®Google Scholar
• Ribeiro, E., Neave, N., Morais, R. N., & Manning, J. T. (2016). Direct versus indirect measurement of digit ratio (2D:4D). Evolutionary Psychology, 14(1), 147470491663253–147470491663253. https://doi.org/10.1177/1474704916632536
   Web of Science ®Google Scholar
• Richards, G., Browne, W. V., Aydin, E., Constantinescu, M., Nave, G., Kim, M. S., & Watson, S. J. (2020). Digit ratio (2D:4D) and congenital adrenal hyperplasia (CAH): Systematic literature review and meta-analysis. Hormones and Behavior, 126, 104867–104867. https://doi.org/10.1016/j.yhbeh.2020.104867
   PubMed Web of Science ®Google Scholar
• Rosenfeld, C. S. (2017). Brain sexual differentiation and requirement of SRY: Why or why not? Frontiers in Neuroscience, 11, 632. https://doi.org/10.3389/fnins.2017.00632
   PubMed Web of Science ®Google Scholar
• Sadr, M., Khorashad, B. S., Talaei, A., Fazeli, N., & Hönekopp, J. (2020). 2D:4D suggests a role of prenatal testosterone in gender dysphoria. Archives of Sexual Behavior, 49(2), 421–432. https://doi.org/10.1007/s10508-020-01630-0
   PubMed Web of Science ®Google Scholar
• Sanders, A. R., Duan, J., Levinson, D. F., Shi, J., He, D., Hou, C., Burrell, G. J., Rice, J. P., Nertney, D. A., Olincy, A., Rozic, P., Vinogradov, S., Buccola, N. G., Mowry, B. J., Freedman, R., Amin, F., Black, D. W., Silverman, J. M., Byerley, W. F., … Gejman, P. V. (2008). No significant association of 14 candidate genes with Schizophrenia in a large European ancestry sample: Implications for psychiatric genetics. The American Journal of Psychiatry, 165(4), 497–506. https://doi.org/10.1176/appi.ajp.2007.07101573
   PubMed Web of Science ®Google Scholar
• Savic, I., & Arver, S. (2011). Sex dimorphism of the brain in male-to-female transsexuals. Cerebral Cortex (New York, N.Y.: 1991), 21(11), 2525–2533. https://doi.org/10.1093/cercor/bhr032
   PubMed Web of Science ®Google Scholar
• Schneider, H., Pickel, J., & Stalla, G. (2006). Typical female 2nd–4th finger length (2D:4D) ratios in male-to-female transsexuals—Possible implications for prenatal androgen exposure. Psychoneuroendocrinology, 31(2), 265–269. https://doi.org/10.1016/j.psyneuen.2005.07.005
   PubMed Web of Science ®Google Scholar
• Schneider, M. A., Spritzer, P. M., Minuzzi, L., Frey, B. N., Syan, S. K., Fighera, T. M., Schwarz, K., Costa, Â. B., da Silva, D. C., Garcia, C. C. G., Fontanari, A. M. V., Real, A. G., Anes, M., Castan, J. U., Cunegatto, F. R., & Lobato, M. I. R. (2019). Effects of estradiol therapy on resting-state functional connectivity of transgender women after gender-affirming related gonadectomy. Frontiers in Neuroscience, 13, 817. https://doi.org/10.3389/fnins.2019.00817
   PubMed Web of Science ®Google Scholar
• Schöning, S., Engelien, A., Bauer, C., Kugel, H., Kersting, A., Roestel, C., Zwitserlood, P., Pyka, M., Dannlowski, U., Lehmann, W., Heindel, W., Arolt, V., & Konrad, C. (2010). Neuroimaging differences in spatial cognition between men and male-to-female transsexuals before and during hormone therapy. The Journal of Sexual Medicine, 7(5), 1858–1867. https://doi.org/10.1111/j.1743-6109.2009.01484.x
   PubMed Web of Science ®Google Scholar
• Seiger, R., Hahn, A., Hummer, A., Kranz, G. S., Ganger, S., Woletz, M., Kraus, C., Sladky, R., Kautzky, A., Kasper, S., Windischberger, C., & Lanzenberger, R. (2016). Subcortical gray matter changes in transgender subjects after long-term cross-sex hormone administration. Psychoneuroendocrinology, 74, 371–379. https://doi.org/10.1016/j.psyneuen.2016.09.028
   PubMed Web of Science ®Google Scholar
• Siegmann, E.-M., Müller, T., Dziadeck, I., Mühle, C., Lenz, B., & Kornhuber, J. (2020). Digit ratio (2D:4D) and transgender identity: New original data and a meta-analysis. Scientific Reports, 10(1), 19326–19326. https://doi.org/10.1038/s41598-020-72486-6
   PubMed Web of Science ®Google Scholar
• Simon, L., Kozák, L. R., Simon, V., Czobor, P., Unoka, Z., Szabó, Á., & Csukly, G. (2013). Regional grey matter structure differences between transsexuals and healthy controls—A voxel based morphometry study. PloS One, 8(12), e83947–e83947. https://doi.org/10.1371/journal.pone.0083947
   Web of Science ®Google Scholar
• Smith, E., Junger, J., Pauly, K., Kellermann, T., Neulen, J., Neuschaefer-Rube, C., Derntl, B., & Habel, U. (2018). Gender incongruence and the brain – Behavioral and neural correlates of voice gender perception in transgender people. Hormones and Behavior, 105, 11–21. https://doi.org/10.1016/j.yhbeh.2018.07.001
   PubMed Web of Science ®Google Scholar
• Smith, E. S., Junger, J., Derntl, B., & Habel, U. (2015). The transsexual brain—A review of findings on the neural basis of transsexualism. Neuroscience and Biobehavioral Reviews, 59, 251–266. https://doi.org/10.1016/j.neubiorev.2015.09.008
   PubMed Web of Science ®Google Scholar
• Soleman, R. S., Schagen, S. E. E., Veltman, D. J., Kreukels, B. P. C., Cohen-Kettenis, P. T., Lambalk, C. B., Wouters, F., & Delemarre-van de Waal, H. A. (2013). Sex differences in verbal fluency during adolescence: A functional magnetic resonance imaging study in gender dysphoric and control boys and girls. The Journal of Sexual Medicine, 10(8), 1969–1977. https://doi.org/10.1111/jsm.12083
   PubMed Web of Science ®Google Scholar
• Sosa, M., Jódar, E., Arbelo, E., Domínguez, C., Saavedra, P., Torres, A., Salido, E., Limiñana, J. M., Gómez De Tejada, M. J., & Hernández, D. (2004). Serum lipids and estrogen receptor gene polymorphisms in male-to-female transsexuals: Effects of estrogen treatment. European Journal of Internal Medicine, 15(4), 231–237. https://doi.org/10.1016/j.ejim.2004.04.009
   PubMedGoogle Scholar
• Spies, M., Hahn, A., Kranz, G. S., Sladky, R., Kaufmann, U., Hummer, A., Ganger, S., Kraus, C., Winkler, D., Seiger, R., Comasco, E., Windischberger, C., Kasper, S., & Lanzenberger, R. (2016). Gender transition affects neural correlates of empathy: A resting state functional connectivity study with ultra high-field 7T MR imaging. NeuroImage, 138, 257–265. https://doi.org/10.1016/j.neuroimage.2016.05.060
   PubMed Web of Science ®Google Scholar
• Stryker, S. (2017). Transgender history: The roots of today’s revolution. Seal Press.
   Google Scholar
• Taziaux, M., Staphorsius, A. S., Ghatei, M. A., Bloom, S. R., Swaab, D. F., & Bakker, J. (2016). Kisspeptin expression in the human infundibular nucleus in relation to sex, gender identity, and sexual orientation. The Journal of Clinical Endocrinology and Metabolism, 101(6), 2380–2389. https://doi.org/10.1210/jc.2015-4175
   PubMed Web of Science ®Google Scholar
• Taziaux, M., Swaab, D. F., & Bakker, J. (2012). Sex differences in the neurokinin B system in the human infundibular nucleus. The Journal of Clinical Endocrinology and Metabolism, 97(12), E2210–E2220. https://doi.org/10.1210/jc.2012-1554
   PubMed Web of Science ®Google Scholar
• Terlecki, M. S., & Newcombe, N. S. (2005). How important is the digital divide? The relation of computer and videogame usage to gender differences in mental rotation ability. Sex Roles, 53(5-6), 433–441. https://doi.org/10.1007/s11199-005-6765-0
   Web of Science ®Google Scholar
• Terlecki, M. S., Newcombe, N. S., & Little, M. (2008). Durable and generalized effects of spatial experience on mental rotation: Gender differences in growth patterns. Applied Cognitive Psychology, 22(7), 996–1013. https://doi.org/10.1002/acp.1420
   Web of Science ®Google Scholar
• Ujike, H., Otani, K., Nakatsuka, M., Ishii, K., Sasaki, A., Oishi, T., Sato, T., Okahisa, Y., Matsumoto, Y., Namba, Y., Kimata, Y., & Kuroda, S. (2009). Association study of gender identity disorder and sex hormone-related genes. Progress in Neuro-Psychopharmacology & Biological Psychiatry, 33(7), 1241–1244. https://doi.org/10.1016/j.pnpbp.2009.07.008
   PubMed Web of Science ®Google Scholar
• Uribe, C., Junque, C., Gómez-Gil, E., Abos, A., Mueller, S. C., & Guillamon, A. (2020). Data for functional MRI connectivity in transgender people with gender incongruence and cisgender individuals. Data in Brief, 31, 105691–105691. https://doi.org/10.1016/j.dib.2020.105691
   PubMed Web of Science ®Google Scholar
• Van Goozen, S. H. M., Slabbekoorn, D., Gooren, L. J. G., Sanders, G., & Cohen-Kettenis, P. T. (2002). Organizing and activating effects of sex hormones in homosexual transsexuals. Behavioral Neuroscience, 116(6), 982–988. https://doi.org/10.1037/0735-7044.116.6.982
   PubMed Web of Science ®Google Scholar
• Veale, J. F. (2014). Evidence against a typology: A taxometric analysis of the sexuality of male-to-female transsexuals. Archives of Sexual Behavior, 43(6), 1177–1186. https://doi.org/10.1007/s10508-014-0275-5
   PubMed Web of Science ®Google Scholar
• Veale, J. F., Clarke, D. E., & Lomax, T. C. (2010). Biological and psychosocial correlates of adult gender-variant identities. Personality and Individual Differences, 48, 252–257. https://doi.org/10.1016/j.paid.2009.09.018
   Web of Science ®Google Scholar
• Veale, J. F., Deutsch, M. B., Devor, A. H., Kuper, L. E., Motmans, J., Radix, A. E., & Amand, C. S. (2022). Setting a research agenda in trans health: An expert assessment of priorities and issues by trans and nonbinary researchers. International Journal of Transgender Health, 1–17. https://doi.org/10.1080/26895269.2022.2044425
   Google Scholar
• Voracek, M. (2014). No effects of androgen receptor gene CAG and GGC repeat polymorphisms on digit ratio (2D:4D): A comprehensive meta-analysis and critical evaluation of research. Evolution and Human Behavior, 35(5), 430–437. https://doi.org/10.1016/j.evolhumbehav.2014.05.009
   Web of Science ®Google Scholar
• Voracek, M., Kaden, A., Kossmeier, M., Pietschnig, J., & Tran, U. S. (2018). Meta-analysis shows associations of digit ratio (2D:4D) and transgender identity are small at best. Endocrine Practice: Official Journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists, 24(4), 386–390. https://doi.org/10.4158/EP-2017-0024
   PubMed Web of Science ®Google Scholar
• Voracek, M., & Loibl, L. M. (2009). Scientometric analysis and bibliography of digit ratio (2D:4D) research, 1998–2008. Psychological Reports, 104(3), 922–956. https://doi.org/10.2466/PR0.104.3.922-956
   PubMed Web of Science ®Google Scholar
• Voracek, M., Manning, J. T., & Dressler, S. G. (2007). Repeatability and interobserver error of digit ratio (2D:4D) measurements made by experts. American Journal of Human Biology: The Official Journal of the Human Biology Council, 19(1), 142–146. https://doi.org/10.1002/ajhb.20581
   PubMed Web of Science ®Google Scholar
• Voyer, D., & Bryden, M. P. (1990). Gender, level of spatial ability, and lateralization of mental rotation. Brain and Cognition, 13(1), 18–29. https://doi.org/10.1016/0278-2626(90)90037-O
   PubMed Web of Science ®Google Scholar
• Wallien, M. S., Zucker, K. J., Steensma, T. D., & Cohen-Kettenis, P. T. (2008). 2D: 4D finger-length ratios in children and adults with gender identity disorder. Hormones and Behavior, 54, 450–454.
   PubMed Web of Science ®Google Scholar
• Wong, W. I., & Hines, M. (2016). Interpreting digit ratio (2D:4D)–behavior correlations: 2D:4D sex difference, stability, and behavioral correlates and their replicability in young children. Hormones and Behavior, 78, 86–94. https://doi.org/10.1016/j.yhbeh.2015.10.022
   PubMed Web of Science ®Google Scholar
• Woo, C.-W., Krishnan, A., & Wager, T. D. (2014). Cluster-extent based thresholding in fMRI analyses: Pitfalls and recommendations. NeuroImage, 91, 412–419. https://doi.org/10.1016/j.neuroimage.2013.12.058
   PubMed Web of Science ®Google Scholar
• Young, W. C., Goy, R. W., & Phoenix, C. H. (1964). Hormones and sexual behavior: Broad relationships exist between the gonadal hormones and behavior. Science (New York, N.Y.), 143(3603), 212–218. https://doi.org/10.1126/science.143.3603.212
   PubMedGoogle Scholar
• Zhou, H.-X., Chen, X., Shen, Y.-Q., Li, L., Chen, N.-X., Zhu, Z.-C., Castellanos, F. X., & Yan, C.-G. (2020). Rumination and the default mode network: Meta-analysis of brain imaging studies and implications for depression. NeuroImage, 206, 116287–116287. https://doi.org/10.1016/j.neuroimage.2019.116287
   PubMed Web of Science ®Google Scholar
• Zhou, J.-N., Hofman, M. A., Gooren, L. J. G., & Swaab, D. F. (1995). A sex difference in the human brain and its relation to transsexuality. Nature, 378(6552), 68–70. https://doi.org/10.1038/378068a0
   PubMed Web of Science ®Google Scholar
• Zou, J., & Schiebinger, L. (2018). AI can be sexist and racist—It’s time to make it fair. Nature, 559(7714), 324–326. https://doi.org/10.1038/d41586-018-05707-8
   PubMedGoogle Scholar
• Zubiaurre-Elorza, L., Junque, C., Gómez-Gil, E., & Guillamon, A. (2014). Effects of cross-sex hormone treatment on cortical thickness in transsexual individuals. The Journal of Sexual Medicine, 11(5), 1248–1261. https://doi.org/10.1111/jsm.12491
   PubMed Web of Science ®Google Scholar
• Zubiaurre-Elorza, L., Junque, C., Gomez-Gil, E., Segovia, S., Carrillo, B., Rametti, G., & Guillamon, A. (2013). Cortical thickness in untreated transsexuals. Cerebral Cortex (New York, N.Y.: 1991), 23(12), 2855–2862. https://doi.org/10.1093/cercor/bhs267
   PubMed Web of Science ®Google Scholar