Polymorphisms near EXOC4 and LRGUK on chromosome 7q32 are associated with Type 2 Diabetes and fasting glucose; the NHLBI Family Heart Study.
BACKGROUND
The chromosome 7q32 region is linked to metabolic syndrome and obesity related traits in the Family Heart Study. As part of a fine mapping study of the region, we evaluated the relationship of polymorphisms to fasting glucose levels and Type 2 diabetes.


METHODS
Thirty-nine HapMap defined tag SNPs in a 1.08 Mb region and a novel deletion polymorphism were genotyped in 2,603 participants of the NHLBI Family Heart Study (FHS). Regression modeling, adjusting for BMI, age, sex, smoking and the TCF7L2 polymorphism, was used to evaluate the association of these polymorphisms with T2D and fasting glucoses levels.


RESULTS
The deletion polymorphism confers a protective effect for T2D, with homozygous deletion carriers having a 53% reduced risk compared to non-deleted carriers. Among non-diabetics, the deletion was significantly associated with lower fasting glucose levels in men (p = 0.038) but not women (p = 0.118). In addition, seven SNPs near the deletion were significantly associated (p < 0.01) to diabetes.


CONCLUSIONS
Chromosome 7q32 contains both SNPs and a deletion that were associated to T2D. Although the deletion region contains several islands of strongly conserved sequence, it is not known to contain a transcribed gene. The closest nearby gene, EXOC4, is involved in insulin-stimulated glucose transport and may be a candidate for this association. Further work is needed to determine if the deletion represents a functional variant or may be in linkage disequilibrium with a functional mutation influencing EXOC4 or another nearby gene.
Laramie
Jason M
JM
Department of Neurology, Boston University School of Medicine, Boston, MA, USA. laramiej@gmail.com
Wilk
Jemma B
JB
Williamson
Sally L
SL
Nagle
Michael W
MW
Latourelle
Jeanne C
JC
Tobin
Jennifer E
JE
Province
Michael A
MA
Borecki
Ingrid B
IB
Myers
Richard H
RH
D001786:Blood Glucose / Q000235:genetics* / Q000378:metabolism*; D002874:Chromosome Mapping; D002897:Chromosomes, Human, Pair 7; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005190:Family; D006331:Heart Diseases / Q000235:genetics; D006801:Humans; D015810:Linkage Disequilibrium; D024821:Metabolic Syndrome / Q000235:genetics; D054555:National Heart, Lung, and Blood Institute (U.S.); D009765:Obesity / Q000235:genetics; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017384:Sequence Deletion; D014481:United States; D033921:Vesicular Transport Proteins / Q000235:genetics*
D001786:Blood Glucose; C489607:EXOC4 protein, human; D033921:Vesicular Transport Proteins