A case of childhood glaucoma with a combined partial monosomy 6p25 and partial trisomy 18p11 due to an unbalanced translocation

ABSTRACT

Background: Chromosomal deletion involving the 6p25 region results in a clinically recognizable syndrome characterized by anterior eye chamber anomalies with risk of glaucoma and non-ocular malformations (6p25 deletion syndrome). We report a newborn infant case of childhood glaucoma with a combination of partial monosomy 6p25 and partial trisomy 18p11 due to an unbalanced translocation.

Materials and methods: The patient was a 0-year-old girl. Both eyes showed aniridia and left eye Peters anomaly with multiple malformations. To identify the chromosomal aberrations in the patient with clinically suspected 6p25 deletion syndrome, we performed cytogenetic analysis (G-banding and multicolor fluorescent in-situ hybridization) and array-based comparative genomic hybridization (array-CGH) analysis.

Results: Cytogenetic analyses revealed a derivative chromosome 6 with its distal short arm replaced by an extra copy of the short arm of chromosome 18. Array-CGH analysis detected a 4.6-Mb deletion at 6pter to 6p25.1 and 8.9-Mb duplication at 18pter to 18p11.22. To determine the breakpoint of the unbalanced rearrangement at the single-base level, we performed a long-range PCR for amplifying the junctional fragment of the translocation breakpoint. By sequencing the junctional fragment, we defined the unbalanced translocation as g.chr6:pter_4594783delinschr18:pter_8911541.

Conclusions: A phenotype corresponding to combined monosomy 6p25 and trisomy 18p11 presented as childhood glaucoma associated with non-acquired (congenital) ocular anomalies consist of aniridia and Peters anomaly and other systemic malformations. To the best of our knowledge, this is the first report which demonstrated the breakpoint sequence of an unbalanced translocation in a Japanese infant with childhood glaucoma.

KEYWORDS:

• 6p25 deletion syndrome
• childhood glaucoma
• unbalanced translocation
• chromosomal aberration
• trisomy 18p

Acknowledgments

We thank the patient and her parents for participating in this study.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Supplementary material

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Additional information

Funding

This work was supported by a grant for the Initiative on Rare and Undiagnosed Diseases from the Japan Agency for Medical Research and Development (AMED) [no. JP18ek0109301 to Y.H] and three Grants-in-Aid for Scientific Research grants from the Japan Society for the Promotion of Science [no. 17K11447 to Y.H, no.16K11284 to K.H, and no. 15K20253 to N.T].