Minority Health and Health Equity Archive
Permanent URI for this collectionhttp://hdl.handle.net/1903/21769
Welcome to the Minority Health and Health Equity Archive (MHHEA), an electronic archive for digital resource materials in the fields of minority health and health disparities research and policy. It is offered as a no-charge resource to the public, academic scholars and health science researchers interested in the elimination of racial and ethnic health disparities.
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Item Ethnicity and Human Genetic Linkage Maps(2005) Jorgenson, Eric; Tang, Hua; Gadde, Maya; Province, Mike; Leppert, Mark; Kardia, Sharon; Schork, Nicholas; Cooper, Richard; Rao, DC; Boerwinkle, Eric; Risch, NeilHuman genetic linkage maps are based on rates of recombination across the genome. These rates in humans vary by the sex of the parent from whom alleles are inherited, by chromosomal position, and by genomic features, such as GC content and repeat density.We have examined—for the first time, to our knowledge—racial/ethnic differences in genetic maps of humans. We constructed genetic maps based on 353 microsatellite markers in four racial/ethnic groups: whites, African Americans, Mexican Americans, and East Asians (Chinese and Japanese). These maps were generated using 9,291 subjects from 2,900 nuclear families who participated in the National Heart, Lung, and Blood Institute–funded Family Blood Pressure Program, the largest sample used for map construction to date. Although the maps for the different groups are generally similar, we did find regional and genomewide differences across ethnic groups, including a longer genome-wide map for African Americans than for other populations. Some of this variation was explained by genotyping artifacts—namely, null alleles (i.e., alleles with null phenotypes) at a number of loci—and by ethnic differences in null-allele frequencies. In particular, null alleles appear to be the likely explanation for the excess map length in African Americans. We also found that nonrandom missing data biases map results. However, we found regions on chromosome 8p and telomeric segments with significant ethnic differences and a suggestive interval on chromosome 12q that were not due to genotype artifacts. The difference on chromosome 8p is likely due to a polymorphic inversion in the region. The results of our investigation have implications for inferences of possible genetic influences on human recombination as well as for future linkage studies, especially those involving populations of nonwhite ethnicity.Item Categorization of humans in biomedical research: genes, race and disease(2002) Risch, Neil; Burchard, Esteban; Ziv, Elad; Tang, HuaA debate has arisen regarding the validity of racial/ethnic categories for biomedical and genetic research. Some claim ‘no biological basis for race’ while others advocate a ‘race-neutral’ approach, using genetic clustering rather than self-identified ethnicity for human genetic categorization. We provide an epidemiologic perspective on the issue of human categorization in biomedical and genetic research that strongly supports the continued use of self-identified race and ethnicity.Item Assessing genetic contributions to phenotypic differences among 'racial' and 'ethnic' groups(2004) Mountain, Joanna L; Risch, NeilDescriptions of human genetic variation given thirty years ago have held up well, considering the substantial accrual of DNA sequence data in the interim. Most importantly, estimates of between-group genetic variation have remained relatively low. Despite the low average level of between-group variation, clusters recently inferred from multilocus genetic data coincide closely with groups defined by self-identified race or continental ancestry. This correspondence implies that genetic factors might contribute to unexplained between-group phenotypic variation. Current understanding of the contribution of genes to variation in most complex traits is limited, however. Under these circumstances, assumptions about genetic contributions to goup differences are unfounded. In the absence of detailed understanding, 'racial' and 'ethnic' categories will remain useful in biomedical research. Further, we suggest approaches and guidelines for assessing the contribution of genetic factors to between-group phenotypic differences, including studies of candidate genes and analyses of recently admixed populations.Item A Genome Scan for Hypertension Susceptibility Loci in Populations of Chinese and Japanese Origins(2003) Ranade, Koustubh; Hinds, David; Hsiung, Chao Agnes; Chuang, Lee-Ming; Chang, Mau-Song; Chen, Ying-Tsung; Pesich, Robert; Hebert, Joan; Chen, Yii-Der I; Dzau, Victor; Olshen, Richard; Curb, David; Botstein, David; Cox, David R; Risch, NeilBackground: Our understanding of genes that predispose to essential hypertension is poor. Methods: A genome-wide scan for linkage at ~10 cM resolution was done on 1425 sibpairs of Chinese and Japanese origins that were concordant for hypertension (N = 661), low–normal blood pressure (BP) (N = 184), or discordant for BP (N = 580). Results: There was no significant evidence of linkage to a single locus in the genome. There was suggestive evidence of linkage to chromosome 10p, with a LOD score of 2.5. Conclusions: We can exclude the possibility that a single gene accounts for at least 15% of the variance in hypertension in this population.