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Common variants at 10 genomic loci influence hemoglobin A₁(C) levels via glycemic and nonglycemic pathways.

TitleCommon variants at 10 genomic loci influence hemoglobin A₁(C) levels via glycemic and nonglycemic pathways.
Publication TypeJournal Article
Year of Publication2010
AuthorsSoranzo N, Sanna S, Wheeler E, et al.
Corporate AuthorsWTCCC
JournalDiabetes
Volume59
Issue12
Pagination3229-39
Date Published2010 Dec
ISSN1939-327X
KeywordsAdult, Blood Glucose, Body Mass Index, Chromosome Mapping, Cohort Studies, European Continental Ancestry Group, Female, Genetic Variation, Genome-Wide Association Study, Glycated Hemoglobin A, Humans, Male, Meta-Analysis as Topic, Middle Aged, Polymorphism, Single Nucleotide
Abstract

OBJECTIVE: Glycated hemoglobin (HbA₁(c)), used to monitor and diagnose diabetes, is influenced by average glycemia over a 2- to 3-month period. Genetic factors affecting expression, turnover, and abnormal glycation of hemoglobin could also be associated with increased levels of HbA₁(c). We aimed to identify such genetic factors and investigate the extent to which they influence diabetes classification based on HbA₁(c) levels.

RESEARCH DESIGN AND METHODS: We studied associations with HbA₁(c) in up to 46,368 nondiabetic adults of European descent from 23 genome-wide association studies (GWAS) and 8 cohorts with de novo genotyped single nucleotide polymorphisms (SNPs). We combined studies using inverse-variance meta-analysis and tested mediation by glycemia using conditional analyses. We estimated the global effect of HbA₁(c) loci using a multilocus risk score, and used net reclassification to estimate genetic effects on diabetes screening.

RESULTS: Ten loci reached genome-wide significant association with HbA(1c), including six new loci near FN3K (lead SNP/P value, rs1046896/P = 1.6 × 10⁻²⁶), HFE (rs1800562/P = 2.6 × 10⁻²⁰), TMPRSS6 (rs855791/P = 2.7 × 10⁻¹⁴), ANK1 (rs4737009/P = 6.1 × 10⁻¹²), SPTA1 (rs2779116/P = 2.8 × 10⁻⁹) and ATP11A/TUBGCP3 (rs7998202/P = 5.2 × 10⁻⁹), and four known HbA₁(c) loci: HK1 (rs16926246/P = 3.1 × 10⁻⁵⁴), MTNR1B (rs1387153/P = 4.0 × 10⁻¹¹), GCK (rs1799884/P = 1.5 × 10⁻²⁰) and G6PC2/ABCB11 (rs552976/P = 8.2 × 10⁻¹⁸). We show that associations with HbA₁(c) are partly a function of hyperglycemia associated with 3 of the 10 loci (GCK, G6PC2 and MTNR1B). The seven nonglycemic loci accounted for a 0.19 (% HbA₁(c)) difference between the extreme 10% tails of the risk score, and would reclassify ∼2% of a general white population screened for diabetes with HbA₁(c).

CONCLUSIONS: GWAS identified 10 genetic loci reproducibly associated with HbA₁(c). Six are novel and seven map to loci where rarer variants cause hereditary anemias and iron storage disorders. Common variants at these loci likely influence HbA₁(c) levels via erythrocyte biology, and confer a small but detectable reclassification of diabetes diagnosis by HbA₁(c).

DOI10.2337/db10-0502
Alternate JournalDiabetes
PubMed ID20858683
PubMed Central IDPMC2992787
Grant ListCZB/4/710 / / Chief Scientist Office / United Kingdom
MC_UP_A100_1003 / / Medical Research Council / United Kingdom
MC_U127561128 / / Medical Research Council / United Kingdom
R01 DK072193 / DK / NIDDK NIH HHS / United States
MC_U106179471 / / Medical Research Council / United Kingdom
G0401527 / / Medical Research Council / United Kingdom
G0701863 / / Medical Research Council / United Kingdom
MC_QA137934 / / Medical Research Council / United Kingdom
MC_U106188470 / / Medical Research Council / United Kingdom