Diabetes, Vol 49, Issue 12 2196-2200, Copyright © 2000 by American Diabetes Association
A common promoter variant of the leptin gene is associated with changes in the relationship between serum leptin and fat mass in obese girls
C Le Stunff, C Le Bihan, NJ Schork and P Bougneres
Unite 342 of the Institut National de la Sante et de la Recherche Medicale and the Pediatric Endocrinology Department, Rene Descartes University, Paris, France.
Mutations in the leptin gene lead to rare obese syndromes of Mendelian
inheritance in humans and rodents. However, no relevant mutations are found
in the coding region of leptin gene DNA in patients with common
multifactorial obesity. These obese patients tend to have an elevation of
serum leptin proportional to their adiposity but with a rather wide
dispersion of leptin levels for a given body fat content, which in part is
attributable to sexual dimorphism. The current study, performed in two
independent Caucasian cohorts of obese girls, shows that a frequent
promoter variant of the leptin gene is associated with changes in the
relationship between serum leptin and body fatness. Girls of comparable
adiposity have different circulating leptin levels, depending on their
genotype at this locus. Girls with the -/- Lep -2,549 genotype have 25%
lower mean leptin levels than the girls with other genotypes, as reflected
by differences in the regression slopes of leptin-to-fat mass. Therefore,
genetic factors related to the leptin gene may be important in defining the
set point of obese individuals (i.e., the circulating leptin level for a
given degree of body fatness). This definition may be of both physiological
and therapeutic relevance, although a phenotypic association with an
individual single-nucleotide polymorphism is not sufficient to assign
function to this particular nucleotide site.