Diabetes, Vol 49, Issue 5 872-875, Copyright © 2000 by American Diabetes Association
The CART gene and human obesity: mutational analysis and population genetics
BG Challis, GS Yeo, IS Farooqi, J Luan, S Aminian, DJ Halsall, JM Keogh, NJ Wareham and S O'Rahilly
University Department of Medicine, Addenbrooke's Hospital, Cambridge, UK.
The cocaine- and amphetamine-regulated transcript (CART) peptide is a
recently characterized neuropeptide implicated in the control of appetite.
We hypothesized that genetic variation in CART may contribute to human
obesity. The entire coding region of CART was determined by nucleotide
sequencing in 91 unrelated subjects with severe early-onset obesity. A
novel amino acid change, Ser66Thr, was found in 2 probands and in 0 of 100
control subjects but did not cosegregate with obesity in family studies.
Two common polymorphisms were found in the 3'-untranslated region (A1475G
and deltaA1457). An effect of these polymorphisms on body composition and
intermediate phenotypes related to obesity was examined in a large
Caucasian population in the U.K. Neither polymorphism showed any
significant relationship with obesity; however, men heterozygous for the
A1475G variant had significantly lower waist-to-hip ratio (WHR), fasting
plasma insulin, and fasting triglycerides. Regression analysis indicated
that the effects on insulin and triglycerides were likely to be secondary
to the effects on WHR. Thus, we have conducted the first systematic study
of the CART gene in human obesity, and although no clear association with
obesity was found, the data suggest that genetic variation in the CART
locus might influence fat distribution and variables related to syndrome X.