Variants in KCNQ1 increase type II diabetes susceptibility in South Asians: a study of 3,310 subjects from India and the US.
BACKGROUND
Polymorphisms in intron 15 of potassium voltage-gated channel, KQT-like subfamily member 1 (KCNQ1) gene have been associated with type II diabetes (T2D) in Japanese genome-wide association studies (GWAS). More recently a meta-analysis of European GWAS has detected a new independent signal associated with T2D in intron 11 of the KCNQ1 gene. The purpose of this investigation is to examine the role of these variants with T2D in populations of Asian Indian descent from India and the US.


METHODS
We examined the association between four variants in the KCNQ1 gene with T2D and related quantitative traits in a total of 3,310 Asian Indian participants from two different cohorts comprising 2,431 individuals of the Punjabi case-control cohort from the Sikh Diabetes Study and 879 migrant Asian Indians living in the US.


RESULTS
Our data confirmed the association of a new signal at the KCNQ1 locus (rs231362) with T2D showing an allelic odds ratio (OR) of 1.24 95%CI [1.08-1.43], p = 0.002 in the Punjabi cohort. A moderate association with T2D was also seen for rs2237895 in the Punjabi (OR 1.14; p = 0.036) and combined cohorts (meta-analysis OR 1.14; p = 0.018). Three-site haplotype analysis of rs231362, rs2237892, rs2237895 exhibited considerably stronger evidence of association of the GCC haplotype with T2D showing OR of 1.24 95%CI [1.00-1.53], p = 0.001, permutation p = 8 × 10-4 in combined cohorts. The 'C' risk allele carriers of rs2237895 had significantly reduced measures of HOMA-B in the US cohort (p = 0.008) as well as in combined cohort in meta-analysis (p = 0.009).


CONCLUSIONS
Our investigation has confirmed that the variation within the KCNQ1 locus confers a significant risk to T2D among Asian Indians. Haplotype analysis further suggested that the T2D risk associated with KCNQ1 SNPs may be derived from 'G' allele of rs231362 and 'C' allele of rs2237895 and this appears to be mediated through β cell function.
Department of Pediatrics, College of Medicine, University of Oklahoma Health Sciences Center Oklahoma City, Oklahoma, USA.
Latonya F
LF
Been
Sarju
S
Ralhan
Gurpreet S
GS
Wander
Narinder K
NK
Mehra
JaiRup
J
Singh
John J
JJ
Mulvihill
Christopher E
CE
Aston
Dharambir K
DK
Sanghera
D016022:Case-Control Studies; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D007194:India; D051657:KCNQ1 Potassium Channel / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D014481:United States
D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human
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