Classical family, twin and adoption studies have indicated a genetic component to bipolar affective disorder (BAD), and a disease prevalence of 1-2% in the population. In order to identify susceptibility loci we have undertaken a 10 cM genomewide screen of 231 individuals from 13 new Australian families. The pedigrees include 33 individuals with bipolar I (BPI), 7 with schizoaffective/mania (SZ/MA) 4 with bipolar II (BPII) and 25 with recurrent unipolar depression (UP), as deter-mined using the Research Diagnostic Criteria diagnostic categories based on the Diagnostic Interview for Genetic Studies (DIGS). All individuals were genotyped for 400 microsatellite markers from the ABI PRISM Linkage Mapping Set Version 2.0 (PE Applied Biosystems) by the Australian Genomic Research Facility, Melbourne, Australia. Analysis of the genotyping data was undertaken using the ANALYZE package. Two different diagnostic models were used in the analysis: Model 1 in which all BPI, BPII and SZ/MA individuals are considered affected and all other family members are considered unaffected; and Model 2 in which all affected individuals from Model 1 and all UP individuals are affected, and all other members are considered unaffected. Data was analyzed using both dominant and recessive models and with two penetrance groups with maximum age-specific penetrance levels of either 60% or 90%. Over all families the maximum lod score obtained was 2.39 (p = 0.0004) for D3S1279 (3q25-q26) from a sibpair analysis on nuclear families using diagnostic model 1. Other two-point lod scores greater than 1.5 were obtained for D9S1776 (9q33) and D19S216 (19p13). Several individual families gave lod scores greater than 2.0. These included lod scores of 2.91 at D13S153 (13q14) in Family 04, 2.38 at D3S1614 (3q25-26) in Family 05, 2.18 at D3S3681 (3p11) in Family 20 and 2.0 at D22S420 (22q11) in Family 03. In addition there was some support for 18p11 in two families, one giving a two-point lod score of 1.8 at D18S53 (Family 17) and another giving a lod score of 1.68 for D18S1102 (Family 22). In conclusion, the results of this genome scan have failed to identify a single major locus. However evidence for potential susceptibility loci has been obtained for chromosomes 3, 13, 18, 22,9 and 19. It is of interest that the loci we have identified on chromosomes 13q14, 18p11 and 22q11 have been implicated by other bipolar disorder genome scans.
|Number of pages||2|
|Journal||American Journal of Medical Genetics - Neuropsychiatric Genetics|
|Publication status||Published - 7 Aug 2000|