Sequence variants of the POMC gene and their associations with body composition in children.

We investigated POMC sequence variants in 242 overweight and nonoverweight African-American and white children and examined the associations between body composition and POMC polymorphisms. Three novel polymorphisms and two previously identified sequence variants were found: A7301G, A7429G, and C8246T were all in untranslated regions. A 9-bp (AGC AGC GGC) duplication/insertion was found between positions 7677 and 7678, and one normal-weight African-American girl had a 45-bp triple duplication/insertion at this location. Compared with whites, African-American children were significantly more likely to have polymorphisms A7301G, A7429G, and the 9-bp insertion. However, there were no significant associations between any of the polymorphisms and body composition. Five African-American subjects who were homozygous for A7429G had a trend (p = 0.08) for a greater BMI-SD score (5.3 +/- 5.3 kg/m(2)) compared with wild-type children (BMI-SD score, 2.4 +/- 3.2 kg/m(2)) or heterozygotes (BMI-SD score, 2.7 +/- 3.7 kg/m(2)). However, there were no differences in BMI-SD score for A7429G when African American subjects were studied separately and both gender and height were taken into account. The contribution of the POMC gene variants we studied to pediatric-onset obesity seems to be limited.