An FTO variant is associated with Type 2 diabetes in South Asian populations after accounting for body mass index and waist circumference

• Published in: Diabetic medicine 2011-06, Vol.28 (6), p.673-680
• Main Authors: Rees, S. D., Islam, M., Hydrie, M. Z. I., Chaudhary, B., Bellary, S., Hashmi, S., O'Hare, J. P., Kumar, S., Sanghera, D. K., Chaturvedi, N., Barnett, A. H., Shera, A. S., Weedon, M. N., Basit, A., Frayling, T. M., Kelly, M. A., Jafar, T. H.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Asian People; Biological and medical sciences; Body Mass Index; Cardiovascular Diseases - epidemiology; Cardiovascular Diseases - etiology; Cardiovascular Diseases - genetics; Diabetes Mellitus, Type 2 - complications; Diabetes Mellitus, Type 2 - epidemiology; Diabetes Mellitus, Type 2 - ethnology; Diabetes Mellitus, Type 2 - genetics; Diabetes. Impaired glucose tolerance; Diabetic Angiopathies - epidemiology; Diabetic Angiopathies - etiology; Diabetic Angiopathies - genetics; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Feeding. Feeding behavior; Female; FTO; Fundamental and applied biological sciences. Psychology; Genetic Predisposition to Disease; Humans; Male; Medical sciences; meta-analysis; Middle Aged; Obesity - complications; Obesity - epidemiology; Obesity - ethnology; Obesity - genetics; Polymorphism, Single Nucleotide; South Asian; Type 2 diabetes; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Waist Circumference - genetics; Young Adult
• ISSN: 0742-3071; 1464-5491; 1464-5491
• DOI: 10.1111/j.1464-5491.2011.03257.x

Diabet. Med. 28, 673–680 (2011) Aims  A common variant, rs9939609, in the FTO (fat mass and obesity) gene is associated with adiposity in Europeans, explaining its relationship with diabetes. However, data are inconsistent in South Asians. Our aim was to investigate the association of the FTO rs9939609 variant with obesity, obesity‐related traits and Type 2 diabetes in South Asian individuals, and to use meta‐analyses to attempt to clarify to what extent BMI influences the association of FTO variants with diabetes in South Asians. Methods  We analysed rs9939609 in two studies of Pakistani individuals: 1666 adults aged ≥ 40 years from the Karachi population‐based Control of Blood Pressure and Risk Attenuation (COBRA) study and 2745 individuals of Punjabi ancestry who were part of a Type 2 diabetes case–control study (UK Asian Diabetes Study/Diabetes Genetics in Pakistan; UKADS/DGP). The main outcomes were BMI, waist circumference and diabetes. Regression analyses were performed to determine associations between FTO alleles and outcomes. Summary estimates were combined in a meta‐analysis of 8091 South Asian individuals (3919 patients with Type 2 diabetes and 4172 control subjects), including those from two previous studies. Results  In the 4411 Pakistani individuals from this study, the age‐, sex‐ and diabetes‐adjusted association of FTO variant rs9939609 with BMI was 0.45 (95% CI 0.24–0.67) kg/m2 per A‐allele (P = 3.0 × 10−5) and with waist circumference was 0.88 (95% CI 0.36–1.41) cm per A‐allele (P = 0.001). The A‐allele (30% frequency) was also significantly associated with Type 2 diabetes [per A‐allele odds ratio (95% CI) 1.18 (1.07–1.30); P = 0.0009]. A meta‐analysis of four South Asian studies with 8091 subjects showed that the FTO A‐allele predisposes to Type 2 diabetes [1.22 (95% CI 1.14–1.31); P = 1.07 × 10−8] even after adjusting for BMI [1.18 (95% CI 1.10–1.27); P = 1.02 × 10−5] or waist circumference [1.18 (95% CI 1.10–1.27); P = 3.97 × 10−5]. Conclusions  The strong association between FTO genotype and BMI and waist circumference in South Asians is similar to that observed in Europeans. In contrast, the strong association of FTO genotype with diabetes is only partly accounted for by BMI.