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

Abstract

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/m²), Québec Family Study (QFS; 77 controls, BMI: 19–26 kg/m² and 38 obese, BMI: 27–56 kg/m²) and Swedish Obese Subjects (SOS) Study (81 controls, BMI: 18–26 kg/m² and 308 obese, BMI: 33–58 kg/m²).

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/m²).

CONCLUSION: We conclude that the mtDNA D-loop Kpn I RSP at bp 16,133 (morph-1) is not a determinant of human obesity.