Diabetes, Vol 42, Issue 4 579-582, Copyright © 1993 by American Diabetes Association
Glucokinase gene variants in the common form of NIDDM
KC Chiu, Y Tanizawa and MA Permutt
Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
To determine whether a structural defect in glucokinase could be a primary
cause of glucose intolerance in the common form of NIDDM, the prevalence of
mutations in the gene in 60 American black NIDDM patients was investigated.
First, by Southern blot analysis of DNA from a subset of randomly selected
subjects (n = 20), no gross deletions, insertions, or rearrangements of the
gene were detected. Next, the 5'-untranslated and coding regions of the
gene were amplified directly from genomic DNA by the polymerase chain
reaction. PCR products were screened for mutations by using single-strand
conformational polymorphism analysis. A total of nine variants were
identified, with two in the 5'-UT regions of islet exon 1, two in the 5'-UT
region of liver exon 1, and five in the coding regions. For islet exon 1, 5
of 60 NIDDM patients had both variants in the 5'-UT region; and for liver
exon 1, two variants each occurred in 1 of 60 NIDDM patients. The coding
region variants included a missense mutation in islet exon 1, substitution
of Ala11 (GCC) with Thr11 (ACC), found in 2 patients. The biological
consequences of this mutation and the mutations in the 5'-UT portion of the
gene have yet to be determined. The rest of the variants were third base
pair changes of codons, i.e., silent. A common polymorphism, which was in
linkage equilibrium with microsatellite repeats GCK1 and GCK2, was found in
intron 9, and a variant in intron 2 in both alleles of 1 patient.(ABSTRACT
TRUNCATED AT 250 WORDS)