Non-replication of an association of CTNNBL1 polymorphisms and obesity in a population of Central European ancestry

Background: A recent genome-wide association (GWA) study of U. S.
Caucasians suggested that eight single nucleotide polymorphisms
(SNPs) in CTNNBL1 are associated with obesity and increased fat
mass. We analysed the respective SNPs in data from our previously
published GWA for early onset obesity (case-control design), in GWA
data from a population-based cohort of adults, and in an
independent family-based obesity study. We investigated whether
variants in CTNNBL1 (including rs6013029) and in three other genes
(SH3PXD2B, SLIT3 and FLJ42133,) were associated with obesity.
Methods: The GWA studies were carried out using Affymetrix (R) SNP
Chips with approximately 500,000 markers each. In the families, SNP
rs6013029 was genotyped using the TaqMan (R) allelic discrimination
assay. The German case-control GWA included 487 extremely obese
children and adolescents and 442 healthy lean individuals. The
adult GWA included 1,644 individuals from a German population-based
study (KORA). The 775 independent German families consisted of
extremely obese children and adolescents and their parents.
Results: We found no evidence for an association of the reported
variants in CTNNBL1 with early onset obesity or increased BMI.
Further, in our family-based study we found no evidence for
over-transmission of the rs6013029 risk-allele T to obese children.
Additionally, we found no evidence for an association of SH3PXD2B,
SLIT3 and FLJ42133 variants in our two GWA samples. Conclusion: We
detected no confirmation of the recent association of variants in
CTNNBL1 with obesity in a population of Central European ancestry.