Research reportA novel relationship for schizophrenia, bipolar and major depressive disorder Part 7: A hint from chromosome 7 high density association screen

•Susceptibility genes on chromosome 7 for the three mental disorder are comprehensively revealed.•A logical relationship for schizophrenia, bipolar, and major depressive disorder is discovered.•Clue for most of the susceptibility genes have been found in neuropsychiatric diseases.

Convergent evidence from genetics, symptology and psychopharmacology imply that there are intrinsic connection between schizophrenia (SCZ), bipolar disorder (BPD) and major depressive disorder (MDD). Also, any two or even three of these disorders could co-existe in some families. A total of 47,144 single nucleotide polymorphism (SNPs) on chromosome 7 were genotyped by Affymetrix Genome-Wide Human SNP array 6.0 on 119 SCZ, 253 BPD (type-I), 177 MDD, and 1000 controls. Associated SNP loci were comprehensively revealed and outstanding susceptibility genes were identified including CNTNAP2. a neurexin family gene. Unexpectedly, flanking genes for up to 94.74 % of of the associated SNPs were replicated (P ≤ 9.9 E-8) in an enlarged cohort of 986 SCZ patients. Considering other convergent evidence, our results further implicate that BPD and MDD are subtypes of SCZ.