肥胖儿童黑皮素4受体基因筛查和突变功能预测研究

Mutation screening and function prediction of melanocortin-4 receptor gene in obese children

目的对肥胖儿童中黑皮素4受体（MC4R）基因编码区进行突变位点筛查,研究其与肥胖相关指标的关系,并对突变可能造成的基因功能改变进行预测。方法选择北京市160例7~18岁重度肥胖和100例体重正常的儿童青少年,进行身体测量和血生化指标检测。使用PCR、单链构象多态性和测序方法进行MC4R基因编码区筛查。使用生物信息学网络数据库对筛出的突变进行功能预测。结果肥胖儿童中筛出杂合子错义突变3例（Val95Ile、Val166Ile、Val179Ala）;在对照组中筛出杂合子错义突变1例（Met218Thr）;Val103Ile变异在肥胖组和对照组中分别有7例（4.4%）和6例（6.0%）（P〉0.05）。其中肥胖组中筛出的Val179Ala为首次发现的杂合子突变。携带Val95Ile、Val166Ile或Val179Ala突变的3例肥胖儿童与未携带这3个突变的其他157例肥胖儿童的BMI、体重、腰围、臀围、血脂指标、血糖和脂肪百分比的比较差异均无统计学意义（P〉0.05）。对筛出的突变进行功能预测,发现上述5个变异均可能对蛋白质功能产生影响。结论在肥胖儿童MC4R基因编码区共发现5个变异,其中Val179Ala为首次发现的新突变;功能预测发现这5个变异均可能对蛋白质的功能造成影响。

Objective To screen the coding region of melanocortin-4 receptor gene（MC4R） for mutations in children, analyze the association of the identified variants with obesity-related phenotypes, and predict the potential functions of the identified variants. Methods A case-control study was conducted in 160 severely obese children and 100 normal-weight controls, all aged 7-18 years. Their anthropometric data were collected and blood tests were performed. The coding region of MC4 R gene was screened by polymerase chain reaction（PCR）, single strand conformation polymorphism and sequencing, and the potential functions of the identified variants were predicted by related online databases. Results Three heterozygous missense mutations were identified in obese children（Val95Ile, Val166 Ile and Val179Ala）, and one heterozygous missense mutation was found in controls（Met218Thr）. Val103 Ile variant was found to be carried by seven subjects in the obese group and six in the control group（P〈0.05）. Val179 Ala was a newly identified heterozygous mutation. No significant differences in BMI, weight, waist circumstance, hip circumstance, serum lipid parameters, fasting glucose, and body fat percentage were found between Val95 Ile, Val166 Ile or Val179 Ala mutation carriers and non-carriers in obese children. The function prediction of the variants showed that all the five identified variants influenced the protein function. Conclusions Five variants were identified in the coding region of MC4 R gene, among which Val179 Ala was newly identified. All the five variants might influence the protein function as evidenced by online prediction.