Investigation of chromosome Y loss in men with schizophrenia

Figures & data

Table 1 Demographic and clinical characteristics of participants for loss of chromosome Y study

	Control (n=214)	Schizophrenia (n=146)	P-value
Age (years) (median [IQR])	58.5 [43.0–68.0]	60.0 [49.0–68.0]	0.125a
Smoking (never/former/current)b	–	42/43/61	–
Age of onset (years) (median [IQR])	–	25.0 [20.0–32.0]	–
Duration of illness (years) (median [IQR])	–	33.0 [18.0–42.0]	–
Antipsychotic dose (mg/day) (median [IQR])c	–	675.0 [375.0–1,250.0]	–
GAF score (mean ± SD)	–	38.0±7.7	–
BPRS score (median [IQR])	–	42.0 [39.0–53.0]	–
Presence of LOY (with LOY/without LOY)	18/196	13/133	0.851d

Notes: Accurate information regarding age of onset and duration of illness was available from the clinical records of 145 of 146 patients with schizophrenia. Accurate information regarding GAF and BPRS scores were available from the clinical records of 69 of 146 patients with schizophrenia.

a P-value between schizophrenia and control groups calculated using Mann–Whitney U-test.

b For smoking status, “never” refers to an individual who has never been a cigarette or cigar smoker, while “former” indicates an individual who had smoked in his lifetime but who was not a smoker at the time of blood sampling, and “current” refers to an individual who was a smoker at the time of blood sampling.

c Antipsychotic dose was calculated based on chlorpromazine equivalents.

d P-value between individuals with and without LOY calculated using Fisher’s exact test.

Abbreviations: IQR, interquartile range; LOY, loss of chromosome Y; GAF, Global Assessment of Functioning; BPRS, Brief Psychiatric Rating Scale.

Table 2 Logistic regression analysis of LOY in peripheral blood samples from patients with schizophrenia and controls

Explanatory variable	Response variable: LOY (Y/X ratio <0.9)
	Ba	P-value	OR	95% CI
Phenotype (CON vs SCZ)	0.01	0.982	1.01	0.46–2.22
Age	0.09	<0.001	1.09	1.05–1.13

Notes: For logistic regression analyses, LOY was the response variable, while phenotype and age were the explanatory variables. Boldface type indicates statistical significance (P<0.05).

a B represents the unstandardized partial regression coefficient.

Abbreviations: LOY, loss of chromosome Y; SCZ, schizophrenia; CON, control.

Figure 1 Relationship between age and Y/X ratio in blood samples from patients with schizophrenia and controls. All P-values and r values were calculated using Spearman’s rho test.

Table 3 Logistic regression analysis of LOY in peripheral blood samples of patients with schizophrenia

Explanatory variable	Response variable: LOY (Y/X ratio <0.9)
	Ba	P-value	OR	95% CI
Duration of illness	0.100	0.007	1.11	1.03–1.19
Smoking status	−0.230	0.560	0.79	0.36–1.74
Antipsychotic dose	−0.0001	0.894	1.00	0.99–1.00

Notes: For logistic regression analyses, LOY was the response variable, while duration of illness, smoking, and antipsychotic dose were the explanatory variables. Boldface type indicates statistical significance (P<0.05).

a B represents the unstandardized partial regression coefficient.

Abbreviation: LOY, loss of chromosome Y.

Figure 2 Dot plot of age for men with and without LOY in schizophrenia.

Notes: The red line represents 53 years of age. Significant differences in age were observed between patients with schizophrenia exhibiting LOY and those without LOY (median age: 68.0 years, IQR [66.0–76.0] years vs median age: 58.0 years, IQR [48.0–67.0] years) (P<0.001). When the analysis was limited to patients over age 53, there was no significant difference between patients with and without LOY (median age: 68.0 years, IQR [66.0–76.0] years vs median age: 65.0 years, IQR [60.0–72.0] years) (P=0.077). ^aP-values between patients with and without LOY were calculated using Mann–Whitney U-tests.
Abbreviations: LOY, loss of chromosome Y; SCZ, schizophrenia; IQR, inter-quartile range.

Figure S1 Correlation between duration of illness and age in patients with schizophrenia. P-value and r values were calculated using Spearman’s rho test.

Table S1 Comparisons of demographic and clinical characteristics between participants with and without LOY in the schizophrenia group

	SCZ with LOY (n=13)	SCZ without LOY (n=80)	P-value
Age (years) (median [IQR])	68.0 [66.0–76.0]	65.0 [60.0–72.0]	0.077a
Duration of illness (years) (median [IQR])	49.0 [43.0–53.0]	38.0 [27.0–44.3]	0.0016a
Smoking (never/former/current)	4/4/5	18/28/34	0.602b
Antipsychotic dose (mg/day) (median [IQR])c	600.0 [325.0–976.0]	610.0 [368.8–1,265.6]	0.561a

Notes:

a P-value calculated using the Mann–Whitney U-test.

b P-value calculated using the Cochran–Armitage trend test.

c Antipsychotic dose was calculated based on chlorpromazine equivalents.

Abbreviations: LOY, loss of chromosome Y; SCZ, schizophrenia; IQR, interquartile range.

Table S2 Logistic regression analysis of LOY in peripheral blood samples of patients with schizophrenia

Explanatory variable	Response variable: LOY (Y/X ratio <0.9)
	Ba	P-value	OR	95% CI
Age	0.062	0.109	1.06	0.99–1.15
Smoking status	−0.109	0.775	0.90	0.42–1.89
Antipsychotic dose	−0.0001	0.745	1.00	0.99–1.00

Notes: For logistic regression analyses, LOY was the response variable, while age, smoking, and antipsychotic dose were the explanatory variables.

a B represents the unstandardized partial regression coefficient.

Abbreviation: LOY, loss of chromosome Y.

Table S3 Smoking rates in Japanese men

Age (years)	Smoking rate in Japan (%)
	20–29	30–39	40–49	50–59	60–69	Age ≥70 years
General populationa	37.6	43.2	43.2	41.0	31.9	16.9
Schizophreniab	0	33.3	50.0	45.2	38.1	34.3

Notes:

a The National Health and Nutrition Survey Japan, 2012.

b Patients with schizophrenia in our study.