title: Polymorphisms in exon 3 of the proopiomelanocortin gene in relation to serum leptin, salivary cortisol, and obesity in Swedish men.
abstract: The objective of the current study was to examine the potential impact of a cryptic trinucleotide repeat polymorphism in exon 3 of proopiomelanocortin (POMC) on serum leptin levels and salivary cortisol, as well as obesity and estimates of insulin, glucose, and lipid metabolism in 284 unrelated Swedish men born in 1944. Moreover, we examined if a single nucleotide polymorphism (SNP) (C-->T) in exon 3 was associated with these characteristics. The amplification of the microsatellite locus yielded a 155-bp fragment and a fragment with one additional copy of the 9-bp repeat unit GGCAGCAGC (164 bp). The allelic frequencies were 0.96 and 0.04, respectively. Tests for differences in phenotype showed that subjects with the longer polymerase chain reaction (PCR) repeat product (n = 21) had significantly higher serum leptin concentrations (P =.024) compared with subjects with the shorter PCR product (n = 230). Salivary cortisol levels, as well as obesity and its related metabolic perturbations, were the same across the POMC genotypes. In conclusion, a microsatellite polymorphism in exon 3 of POMC is associated with elevated serum leptin levels. This association might reflect variations in melanocortin expression and/or activity, because exon 3 contains, among others, the coding sequences for melanocortins.
authors.affiliation: Department of Internal Medicine, Research Centre for Endocrinology and Metabolism, Göteborg University, Gröna Stråket 8, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden.
authors.forename: Roland
authors.initials: R
authors.lastname: Rosmond
authors.forename: Olavi
authors.initials: O
authors.lastname: Ukkola
authors.forename: Claude
authors.initials: C
authors.lastname: Bouchard
authors.forename: Per
authors.initials: P
authors.lastname: Björntorp
mesh_terms: D000483:Alleles; D001786:Blood Glucose / Q000032:analysis; D001824:Body Constitution; D015992:Body Mass Index; D005091:Exons; D005787:Gene Frequency; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood*; D008055:Lipids / Q000097:blood; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D009154:Mutation; D009765:Obesity / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D011333:Pro-Opiomelanocortin / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid; D012463:Saliva / Q000737:chemistry*; D013548:Sweden
chemical_list: D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D008055:Lipids; D011333:Pro-Opiomelanocortin; D006854:Hydrocortisone