A study of 708 families bolsters evidence that some of the genes conferring susceptibility to bipolar disorder are shared with schizophrenia. Goes et al. (p.
236) found that mood-incongruent psychotic symptoms of bipolar disorder are transmitted within families and are associated with chromosomal regions 13q21-33 and 2p11-q14. The linkage to 13q21-33 supports previous findings of overlap between bipolar disorder and schizophrenia in this region. Until now, 2p11-q14 has been tied to schizophrenia but not bipolar disorder. Dr. Linda Brzustowicz comments on these findings in an editorial on p.
192. Holmans et al. (p.
248) discovered an association between recurrent, early-onset depression and chromosomal region 15q25-q26. In addition, the genome scan of 656 families indicated that this disorder is related to chromosomes 17p12 and 8p22-p21.3 in a sex-specific fashion. The families were also tested for known DNA markers within region 15q25-q26, and the results appear in a companion article by Levinson et al. (p.
259). This fine-mapping narrowed down the genetic location that appears to confer susceptibility to depression. This locus could account for up to 25% of the increased risk of recurrent, early-onset depression among siblings of individuals with the same disorder. Dr. Peter McGuffin discusses these findings in an editorial on p.
195.