An exploratory association study of the influence of dysbindin and neuregulin polymorphisms on brain morphometry in patients with schizophrenia and healthy subjects from South India.

Multiple genetic risk variants may act in a convergent manner leading on to the pathophysiological alterations of brain structure and function in schizophrenia. We examined the effect of polymorphisms of two candidate genes that mediate glutamatergic signaling, viz., dysbindin (rs1011313) and neuregulin (rs35753505), on brain morphometry in patients with schizophrenia (N=38) and healthy subjects (N=37) from South India. Patients with schizophrenia showed trend-level (p<0.001 uncorrected, 20 voxel extent correction) volumetric reductions in multiple brain regions when compared to healthy control subjects. Trend-level volumetric differences were also noted between homozygotes of the risk allele (AA) of the neuregulin (NRG1) polymorphism and heterozygotes (AG), as well as homozygotes of the risk allele (CC) of the dysbindin (DTNBP1) polymorphism and heterozygotes (TC), irrespective of diagnosis. Moreover, an additive effect of the risk alleles on brain morphometry was also noted. These preliminary findings highlight the possible influence of polymorphisms of risk genes on brain morphometry in schizophrenia.