NIMH Genetics Initiative Millenium Schizophrenia Consortium: linkage analysis of African-American pedigrees.

The NIMH Genetics Initiative is a multi-site collaborative study designed to create a national resource for genetic studies of complex neuropsychiatric disorders. Schizophrenia pedigrees have been collected at three sites: Washington University, Columbia University, and Harvard University. This article-one in a series that describes the results of a genome-wide scan with 459 short-tandem repeat (STR) markers for susceptibility loci in the NIMH Genetics Initiative schizophrenia sample-presents results for African-American pedigrees. The African-American sample comprises 30 nuclear families and 98 subjects. Seventy-nine of the family members were considered affected by virtue of having received a DSMIII-R diagnosis of schizophrenia (n = 71) or schizoaffective disorder, depressed (n = 8). The families contained a total of 42 independent sib pairs. While no region demonstrated evidence of significant linkage using the criteria suggested by Lander and Kruglyak, several regions, including chromosomes 6q16-6q24, 8pter-8q12, 9q32-9q34, and 15p13-15q12, showed evidence consistent with linkage (P = 0.01-0.05), providing independent support of findings reported in other studies. Moreover, the fact that different genetic loci were identified in this and in the European-American samples, lends credence to the notion that these genetic differences together with differences in environmental exposures may contribute to the reported differences in disease prevalence, severity, comorbidity, and course that has been observed in different racial groups in the United States and elsewhere.