Browsing by Author "Gentile, Karen"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Genetic Overlap of Schizophrenia and Bipolar Disorder in a High-Density Linkage Survey inthe Portuguese Island PopulationPublication . Fanous, Ayman H.; Middleton, Frank A.; Gentile, Karen; Amdur, Richard L.; Maher, Brion S.; Zhao, Zhongming; Sun, Jingchun; Medeiros, Helena; Carvalho, Célia; Ferreira, Susana R.; Macedo, António; Knowles, James A.; Azevedo, Maria H.; Pato, Michele T.; Pato, Carlos N.Recent family and genome-wide association studies strongly suggest shared genetic risk factors for schizophrenia (SZ) and bipolar disorder (BP). However, linkage studies have not been used to test for statistically significant genome-wide overlap between them. Forty-seven Portuguese families with sibpairs concordant for SZ, BP, or psychosis (PSY, which includes either SZ or psychotic BP) were genotyped for over 57,000 markers using the Affymetrix 50K Xba SNP array. NPL and Kong and Cox LOD scores were calculated in Merlin for all three phenotypes. Empirical significance was determined using 1,000 gene-dropping simulations. Significance of genome-wide genetic overlap between SZ and BP was determined by the number of simulated BP scans having the same number of loci jointly linked with the real SZ scan, and vice versa. For all three phenotypes, a number of regions previously linked in this sample remained so. For BP, chromosome 1p36 achieved significance (11.54-15.71 MB, LOD = 3.51), whereas it was not even suggestively linked at lower marker densities, as did chromosome 11q14.1 (89.32-90.15 MB, NPL = 4.15). Four chromosomes had loci at which both SZ and BP had NPL ≥ 1.98, which was more than would be expected by chance (empirical P = 0.01 using simulated SZ scans; 0.07 using simulated BP scans), although they did not necessarily meet criteria for suggestive linkage individually. These results suggest that high-density marker maps may provide greater power and precision in linkage studies than lower density maps. They also further support the hypothesis that SZ and BP share at least some risk alleles.
- Genomewide Linkage Analysis of Bipolar Disorder by Use of a High Density Single-Nucleotide–Polymorphism (SNP) Genotyping Assay : A Comparison with Microsatellite Marker Assays and Finding of Significant linkage to Chromosome 6q22Publication . Middleton, Frank A.; Pato, Michele T.; Gentile, Karen; Morley, C. P.; Zhao, X.; Eisener, A. F.; Brown, A.; Petryshen, T. L.; Kirby, A. N.; Medeiros, Helena; Carvalho, Célia; Macedo, António; Dourado, A.; Coelho, I.; Valente, J.; Soares, M. J.; Ferreira, Carlos Paz; Lei, M.; Azevedo, Maria H.; Kennedy, J. L.; Daly, M. J.; Sklar, P.; Pato, Carlos N.We performed a linkage analysis on 25 extended multiplex Portuguese families segregating for bipolar disorder, by use of a high-density single-nucleotide-polymorphism (SNP) genotyping assay, the GeneChip Human Mapping 10K Array (HMA10K). Of these families, 12 were used for a direct comparison of the HMA10K with the traditional 10-cM microsatellite marker set and the more dense 4-cM marker set. This comparative analysis indicated the presence of significant linkage peaks in the SNP assay in chromosomal regions characterized by poor coverage and low information content on the microsatellite assays. The HMA10K provided consistently high information and enhanced coverage throughout these regions. Across the entire genome, the HMA10K had an average information content of 0.842 with 0.21-Mb intermarker spacing. In the 12-family set, the HMA10K-based analysis detected two chromosomal regions with genomewide significant linkage on chromosomes 6q22 and 11p11; both regions had failed to meet this strict threshold with the microsatellite assays. The full 25-family collection further strengthened the findings on chromosome 6q22, achieving genomewide significance with a maximum nonparametric linkage (NPL) score of 4.20 and a maximum LOD score of 3.56 at position 125.8 Mb. In addition to this highly significant finding, several other regions of suggestive linkage have also been identified in the 25-family data set, including two regions on chromosome 2 (57 Mb, NPL = 2.98; 145 Mb, NPL = 3.09), as well as regions on chromosomes 4 (91 Mb, NPL = 2.97), 16 (20 Mb, NPL = 2.89), and 20 (60 Mb, NPL = 2.99). We conclude that at least some of the linkage peaks we have identified may have been largely undetected in previous whole-genome scans for bipolar disorder because of insufficient coverage or information content, particularly on chromosomes 6q22 and 11p11.