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Molecular scanning for mutations in the melanocortin-4 receptor gene in obese/diabetic Japanese
1The first Department of Medicine, Wakayama University of Medical Science, 811-1 Kimi-idera, Waykayama 641-8509, Japan.
Abstract:
Decreased function of the melanocortin-4 receptor (MC4R) was reported to cause late-onset obesity and insulin resistance in rodents. Thus mutations in the MC4R gene drew strong attention as a possible cause of obesity and diabetes. We screened for mutations in the MC4R gene in extremely obese [body mass index (BMI) > or = 35 kg/m2] Japanese with diabetes by direct sequencing. A heterozygous mutation (V103I) was detected in one case (2.0 %), however the frequency was not significantly different from that in non-obese (BMI < or = 24 kg/m2) and non-diabetic subjects (2.7 %). No other mutations were detected. These results suggest that mutations including V103I in the MC4R gene are not a major cause of obesity or diabetes in Japanese.
Insights
Mutations in the melanocortin-4 receptor (MC4R) gene are not a major cause of obesity or diabetes in Japanese individuals. A specific MC4R mutation (V103I) was found, but not at a significant frequency to support this link.
Area of Science:
- Genetics and Molecular Biology
- Endocrinology
- Metabolic Diseases
Background:
- Decreased melanocortin-4 receptor (MC4R) function is linked to obesity and insulin resistance in rodents.
- MC4R gene mutations are investigated as potential causes of human obesity and diabetes.
Purpose of the Study:
- To screen for mutations in the MC4R gene in extremely obese Japanese individuals with diabetes.
- To determine if MC4R gene mutations are a significant cause of obesity and diabetes in this population.
Main Methods:
- Direct sequencing of the MC4R gene was performed.
- Genetic screening was conducted in extremely obese (BMI ≥ 35 kg/m2) Japanese patients with diabetes.
- Mutation frequencies were compared to non-obese, non-diabetic control subjects.
Main Results:
- A heterozygous MC4R mutation (V103I) was identified in one obese, diabetic patient (2.0%).
- The frequency of this mutation was not significantly different from control subjects (2.7%).
- No other MC4R gene mutations were detected in the screened population.
Conclusions:
- MC4R gene mutations, including V103I, do not appear to be a major genetic factor contributing to obesity or diabetes in the Japanese population studied.
- Further research may be needed to explore other genetic or environmental factors involved in obesity and diabetes in this demographic.
