A mitochondrial DNA D-loop polymorphism and obesity in three cohorts of women

OBJECTIVE: To examine the hypothesis of an association between a mtDNA D-loop Kpn I restriction site polymorphism (RSP) at base pair (bp) 16,133 (morph-1) and obesity in women. DESIGN: Comparisons of carriers and noncarriers of the mutation for BMI (Body Mass Index) levels and of the frequency of the mutation in obese and normal weight women. SUBJECTS: 567 unrelated adult Caucasian non-diabetic women from the HERITAGE Family Study (n = 63; BMI: 15-47 kg/m(2)), Quebec Family Study (QFS; 77 controls, BMI: 19 - 26 kg/m(2) and 38 obese, BMI: 27 - 56 kg/m(2)) and Swedish Obese Subjects (SOS) Study (81 controls, BMI: 18 - 26 kg/m(2) and 308 obese, BMI: 33 - 58 kg/m(2)), MEASUREMENTS: BMI was calculated from weight and height (kg/m2), mtDNA was amplified between base pair 15,928 and 16,500 by polymerase chain reaction (PCR) and digested with the restriction endonuclease Kpn I RESULTS: No significant differences in the age-adjusted BMI for the mtDNA D-loop Kpn I RSP at base pair (bp) 16,133 (morph-1) between carriers and non-carriers in the HERITAGE cohort, No significant association was found between BMI and the Kpn I RSP carrier status in the SOS and QFS cohorts. The observed frequencies for the Kpn I RSP were not significantly (P > 0.05) different between the SOS controls and SOS obese irrespective of the degree of severity of obesity (BMI > 40, > 45 or > 50 kg/m(2)). CONCLUSION: We conclude that the mtDNA D-loop Kpn I RSP at bp 16,133 (morph-1) is not a determinant of human obesity.