Association of SNPs and haplotypes in APOL1, 2 and 4 with schizophrenia

Prior work found the APOL1, 2 and 4 genes, located on chromosome 22q12.3-q13.1, to be upregulated in brains of schizophrenic patients. We performed a family-based association study using 130 SNPs tagging the APOL gene family (APOL1-6). The subjects were 112 African-American (AA), 114 European-American (EA), 109 Chinese (Ch) and 42 Japanese (Jp) families with schizophrenia (377 families, 1161 genotyped members and 647 genotyped affected in total). Seven SNPs had p-values<0.05 in the APOL1, 2 and 4 regions for the AA, EA and combined (AA and EA) samples. In the AA sample, two SNPs, rs9610449 and rs6000200 showed low p-values; and a haplotype which comprised these two SNPs yielded a p-value of 0.00029 using the global test (GT) and the allele specific test (AST). The two SNPs and the haplotype were associated with risk for schizophrenia in African-Americans. In the combined (AA and EA) sample, two SNPs, rs2003813 and rs2157249 showed low p-values; and a three SNP haplotype including these two SNPs was significant using the GT (p=0.0013) and the AST (p=0.000090). The association of this haplotype with schizophrenia was significant for the entire (AA, EA, Ch and Jp) sample using the GT (p=0.00054) and the AST (p=0.00011). Although our study is not definitive, it suggests that the APOL genes should be more extensively studied in schizophrenia.