Diabetes, Vol 43, Issue 4 558-563, Copyright © 1994 by American Diabetes Association
Linkage analysis of acute insulin secretion with GLUT2 and glucokinase in Pima Indians and the identification of a missense mutation in GLUT2
RC Janssen, C Bogardus, J Takeda, WC Knowler and DB Thompson
Department of Zoology, Arizona State University, Tempe.
The acute insulin response (AIR), a measure of pancreatic beta-cell
function, aggregates in families and is a predictor for the development of
non-insulin-dependent diabetes mellitus (NIDDM) in insulin-resistant Pima
Indians. To assess the genetic components of AIR and NIDDM, polymorphic
dinucleotide repeat regions in two candidate genes, the liver/islet glucose
transporter gene (GLUT2) and the glucokinase gene, were evaluated. Sib-pair
linkage analyses were performed to determine if linkage exists between
these marker loci and measurements of AIR and NIDDM. No linkage was found
between glucokinase and either AIR or NIDDM. Robust sib-pair linkage
analyses suggest linkage between GLUT2 and acute insulin response (P =
0.04), but no linkage was observed with NIDDM. The coding region of the
GLUT2 gene was screened for mutations using polymerase chain
reaction-single-strand conformation polymorphism analysis. A single base
change was identified in exon 3 in approximately 5% of the study
population, and it constitutes the first reported mutation in the human
GLUT2 gene. This base change resulted in an amino acid substitution
(Thr110-->Ile110) in the second membrane-spanning region of the GLUT2
protein. No significant association was noted between AIR and the presence
or absence of the mutation. Thus, this mutation in GLUT2 is unlikely the
cause of a low AIR in Pima Indians.