Objective: The chromosomal region, 15q13-q14, including the α7 nicotinic acetylcholine receptor gene, CHRNA7, is a replicated region for schizophrenia. This study fine-mapped genes at 15q13-q14 to determine whether the association is unique to CHRNA7.
Methods: Family-based and case-control association studies were performed on Caucasian-non-Hispanic and African-American individuals from 120 families as well as 468 individual patients with schizophrenia and 144 well-characterized controls. Single-nucleotide polymorphism (SNP) markers were genotyped, and association analyses carried out for the outcomes of schizophrenia, smoking, and smoking in schizophrenia.
Results: Three genes were associated with schizophrenia in both ethnic populations: TRPM1, KLF13, and RYR3. Two SNPs in CHRNA7 were associated with schizophrenia in African-Americans, and a second SNP in CHRNA7 was significant for an association with smoking and smoking in schizophrenia in Caucasians.
Conclusion: Results of these studies support association of the 15q13-q14 region with schizophrenia. The broad positive association suggests that more than one 15q gene may be contributing to the disorder, either in combination or through a regulatory mechanism.