Familial heritability of increased homocysteine in schizophrenia

Objective: A recent meta-analysis (Muntjewerff et al., 2006) reported findings
that homocysteine levels are increased in plasma in schizophrenia. We attempted
(Stahl et al., 2005) to find nutritional and life styles factors to explain this
increase, but could explain only 24% of the variance environmentally. We
therefore planned a familial genetic study.
Methods: Schizophrenic patients with available siblings were contacted. Consenting siblings and patients were sampled for homocysteine as described
previously (Levine et al., 2002). Mean homocysteine levels of the patients was
14.1mM and that of the siblings was 11.9mM, compared to population mean of
10.6mM.
Results: Pearson correlation of patients vs. siblings was 0.35. These preliminary data suggest about 70% heritability of increased homocysteine levels in
schizophrenia. The sample will be expanded over the next few months.
Conclusions: Homocysteine levels may be a genetic marker or endophenotype
for schizophrenia prophylaxis.