Linkage of c-Harvey-ras-1 and INS DNA markers to unipolar depression and alcoholism is ruled out in 18 families.

Eighteen families informative for c-Harvey-ras-1 and INS DNA markers were tested for linkage to unipolar depression and alcoholism. No evidence of linkage was found between these DNA markers and the disorders observed in the families. This study fails to replicate the Old Order Amish Study and suggests that a significant degree of genetic heterogeneity may be present among psychiatric disorders.