Genome-wide linkage scan in Gullah-speaking African American families with type 2 diabetes: the Sea Islands Genetic African American Registry (Project SuGAR).
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).


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.
Center for Public Health Genomics, University of Virginia, Charlottesville, Virginia, USA. msale@virginia.edu
Michèle M
MM
Sale
Lingyi
L
Lu
Ida J
IJ
Spruill
Jyotika K
JK
Fernandes
Kerry H
KH
Lok
Jasmin
J
Divers
Carl D
CD
Langefeld
W Timothy
WT
Garvey
D001741:Black or African American / Q000235:genetics*; D002874:Chromosome Mapping / Q000379:methods; D002893:Chromosomes, Human, Pair 3 / Q000235:genetics; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000235:genetics*; D005192:Family Health; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D055106:Genome-Wide Association Study / Q000379:methods*; D005838:Genotype; D006801:Humans; D008126:Lod Score; D020641:Polymorphism, Single Nucleotide; D012042:Registries / Q000706:statistics & numerical data; D013022:South Carolina