Publications (3)14.9 Total impact
- [show abstract] [hide abstract]
ABSTRACT: Bipolar affective disorder (BPAD) is a common psychiatric disorder with complex genetic aetiology. We have undertaken a genome-wide scan in one of the largest samples of bipolar affected sibling pairs (ASPs) using a two-stage approach combining sample splitting and marker grid tightening. In this second stage analysis, we have examined 17 regions that achieved a nominally significant maximum likelihood LOD score (MLS) threshold of 0.74 (or 1.18 for the X-chromosome) in stage one. The second stage has added 135 ASP families to bring the total stage 2 sample to 395 ASPs. In total, 494 microsatellite markers have been used to screen the human genome at a density of 10 cM in the first stage sample (260 ASPs) and 5 cM in the second stage. Under the broad diagnostic model, two markers gave LOD scores exceeding 3 with two-point analysis: D4S392 (LOD=3.30) and D10S197 (LOD=3.18). Multipoint analysis demonstrated suggestive evidence of linkage between BPAD and chromosomal regions 6q16–q21 (MLS=2.61) and 4q12–q21 (MLS=2.38). 6q16–q21 is of particular interest because our data, together with those from two recent genome scans, make this the best supported linkage region in BPAD. Further, our data show evidence of a gender effect at this locus with increased sharing predominantly within the male–male pairs. Our scan also provides support for linkage (MLS1.5) at several other regions that have been implicated in meta-analyses of bipolar disorder and/or schizophrenia including 9p21, 10p14–p12 and 18q22.Molecular Psychiatry 10/2005; · 14.90 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Context Traditionally, the search for genes involved in predisposition to major psychoses has proceeded with separate studies of schizophrenia and bipolar disorder. However, twin data suggest that, in addition to genes with specificity for these phenotypes, there exist genes that simultaneously influence susceptibility to schizophrenia, bipolar disorder, and schizoaffective disorder. Objective To undertake, to our knowledge, the first systematic search for such loci. Design Genomewide linkage scan. Setting Affected individuals were ascertained in the United Kingdom and Ireland from general psychiatric inpatient and outpatient services. Participants The families were selected for linkage studies of either schizophrenia or bipolar disorder. Pedigrees were selected for the current analysis where there was at least 1 member with DSM-IV schizoaffective disorder, bipolar type. Within these pedigrees, individuals were coded as affected if they had been diagnosed with DSM-IV schizophrenia, schizoaffective disorder of bipolar type, or bipolar I disorder. A total of 24 pedigrees contributed 35 affected sibling pairs to the sample. Method A 10-centimorgan genome scan using microsatellite markers was analyzed using MAPMAKER/SIBS software. Results A genomewide significant signal (LOD = 3.54) was observed at chromosome 1q42 (near D1S2800), and suggestive LOD scores were observed at chromosomes 22q11 (LOD = 1.96) and 19p13 (LOD = 1.85). No linkage was observed in these regions in our original schizophrenia or bipolar scans in individuals from the United Kingdom. Conclusions Our linkage findings strongly support the existence of loci that influence susceptibility across the functional psychosis spectrum. The DISC1 gene lies within 2.5 megabases of our peak marker on chromosome 1q42 and has been previously implicated in schizophrenia, bipolar disorder, and, recently, schizoaffective disorder. Follow-up of this region should use samples enriched for cases of schizoaffective disorder. Our findings have similar implications for the search for genetic variation on chromosome 22q11 that influences susceptibility to psychosis.