Table 1.

Demographic Data and Genotype Sample for All Diagnostic Groups

	Mean			Standard deviation
	Patients	Siblings	Controls	Patients	Siblings	Controls
n	20	15	66
Age (in years)	21.7	21.5	20.8	3.3	2.9	3.5
Sex (% male)	95	53	44
Parent’s edu. (years)	14.8	14.8	14.5	2.4	2.2	1.9
Education (years)	11.5	13.3	13.1	2.0	2.9	2.6
Handedness (% right)	80	93	81
Valine Homozygotes	10	6	21
Methionine Carriers	10	9	45

Note: The proportion of males and females differed significantly between the patient and sibling groups (χ² (1) = 8.44, p < .01) and between the patient and control groups (χ² (1) = 16.2, p < .001). No gender differences were observed between the siblings and control groups. No differences in our results were observed when gender was entered as a covariate. The three diagnostic groups differed in years of education (F (2, 98) = 3.87, p = 0.02), with both siblings and controls having more personal education than patients. However, the groups did not differ in parental socioeconomic status (F (2, 98) = 0.26, p > 0.50), or age (F (2, 98) = 0.64, p > 0.50).