Genome-Wide Linkage Scan in Gullah-Speaking African American Families With Type 2 Diabetes

The Sea Islands Genetic African American Registry (Project SuGAR)

  1. W. Timothy Garvey6,7
  1. 1Center for Public Health Genomics, University of Virginia, Charlottesville, Virginia
  2. 2Department of Medicine, University of Virginia, Charlottesville, Virginia
  3. 3Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia
  4. 4Department of Biostatistical Sciences, Wake Forest University School of Medicine, Winston-Salem, North Carolina
  5. 5Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
  6. 6Department of Nutrition Sciences, University of Alabama, Birmingham, Alabama
  7. 7Birmingham VA Medical Center, Birmingham, Alabama
  1. Corresponding author: Michèle M. Sale, msale{at}virginia.edu

Abstract

OBJECTIVE—The Gullah-speaking African American population from the Sea Islands of South Carolina is characterized by a low degree of European admixture and high rates of type 2 diabetes and diabetic complications. Affected relative pairs with type 2 diabetes were recruited through the Sea Islands Genetic African American Registry (Project SuGAR).

RESEARCH DESIGN AND METHODS—We conducted a genome-wide linkage scan, genotyping 5,974 single nucleotide polymorphisms in 471 affected subjects and 50 unaffected relatives from 197 pedigrees. Data were analyzed using a multipoint engine for rapid likelihood inference and ordered subsets analyses (OSAs) for age at type 2 diabetes diagnosis, waist circumference, waist-to-hip ratio, and BMI. We searched for heterogeneity and interactions using a conditional logistic regression likelihood approach.

RESULTS—Linkage peaks on chromosome 14 at 123–124 cM were detected for type 2 diabetes (logarithm of odds [LOD] 2.10) and for the subset with later age at type 2 diabetes diagnosis (maximum LOD 4.05). Two linkage peaks on chromosome 7 were detected at 44–45 cM for type 2 diabetes (LOD 1.18) and at 78 cM for type 2 diabetes (LOD 1.64) and the subset with earlier age at type 2 diabetes diagnosis (maximum LOD 3.93). The chromosome 14 locus and a peak on 7p at 29.5 cM were identified as important in the multilocus model. Other regions that provided modest evidence for linkage included chromosome 1 at 167.5 cM (LOD 1.51) and chromosome 3 at 121.0 cM (LOD 1.61).

CONCLUSIONS—This study revealed a novel type 2 diabetes locus in an African American population on 14q that appears to reduce age of disease onset and confirmed two loci on chromosome 7.

Footnotes

  • Published ahead of print at http://diabetes.diabetesjournals.org on 3 October 2008.

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    • Received February 12, 2008.
    • Accepted September 17, 2008.
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  1. Diabetes vol. 58 no. 1 260-267
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