Vesicle-associated membrane protein 4, a positional candidate gene on 1q24-q25, is not associated with type 2 diabetes in the Old Order Amish.
OBJECTIVE
The vesicle-associated membrane protein-4 (VAMP4) gene is an excellent type 2 diabetes (T2DM) positional candidate gene. It is located on chromosome 1q24-q25, a region of linkage to T2DM in the Amish and several other populations. VAMP4 is expressed in liver and skeletal muscle and participates in intracellular trafficking of secreted and membrane-associated proteins.


METHODS
We sequenced VAMP4 in 20 Amish subjects. Polymorphisms in and around VAMP4 were genotyped in 65 Amish subjects with T2DM, 64 subjects with impaired glucose homeostasis (IGH), and 126 normal glucose tolerant controls, as well as in an expanded set of 749 participants of the Amish Family Diabetes Study for whom glucose and insulin levels during an oral glucose tolerance test (OGTT) and other quantitative traits related to diabetes were available. Case-control and quantitative trait association analyses were performed.


RESULTS
We found three common non-coding intragenic polymorphisms: a 23bp insertion/deletion (I/D) in the 5' untranslated region (UTR) in exon 1 at position 73127, and G35319T and C335296T single nucleotide polymorphisms (SNPs) in the 3' UTR (NCBI Accession No. Z98751). The two 3' UTR SNPs were in complete linkage disequilibrium (LD) and both were in strong LD with the exon 1 I/D polymorphism (|D'|=0.82). Similarly, three extragenic flanking SNPs (rs978985, rs203255, and rs1023479) showed moderate LD with the neighboring intragenic SNPs (|D'|=0.23-0.69). None of the SNPs individually nor any of the 2-, 3-, 4-, or 5-polymorphism haplotypes were associated with T2DM or IGH. The exon 1 I/D polymorphism was not associated with significant differences in mean fasting or stimulated glucose or insulin levels during an OGTT or other diabetes-related quantitative traits in the expanded set of 749 subjects.


CONCLUSIONS
Variation in VAMP4 does not significantly influence risk of T2DM or IGH in the Amish.
Sabra
Mona M
MM
Division of Endocrinology, Diabetes and Nutrition, University of Maryland School of Medicine, Baltimore, MD, United States.
Damcott
Coleen
C
Fu
Mao
M
Ott
Sandra
S
O'Connell
Jeffrey R
JR
Mitchell
Braxton D
BD
Shuldiner
Alan R
AR
D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics*; D000328:Adult; D016022:Case-Control Studies; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D005828:Genetics, Population; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010414:Pennsylvania; D020641:Polymorphism, Single Nucleotide; D050683:R-SNARE Proteins; D012306:Risk; D044465:White People / Q000235:genetics*
D033942:Adaptor Proteins, Vesicular Transport; D050683:R-SNARE Proteins; C476456:VAMP4 protein, human