Diabetes, Vol 43, Issue 5 730-733, Copyright © 1994 by American Diabetes Association
Six mutations in the glucokinase gene identified in MODY by using a nonradioactive sensitive screening technique
J Hager, H Blanche, F Sun, NV Vaxillaire, W Poller, D Cohen, P Czernichow, G Velho, JJ Robert, N Cohen and al. et
Human Polymorphism Study Center (C.E.P.H.-Fondation Jean Dausset, Paris, France.
We have reported that 56% of French families with maturity-onset diabetes
of the young (MODY) carry a mutation in the glucokinase gene (GCK).
Therefore, we have established a quick and sensitive nonradioactive
technique (with the PhastSystem based on single-strand conformation
polymorphism [SSCP] analysis) to routinely screen the 12 exons of GCK for
mutations. We have studied GCK in 12 young hyperglycemic patients with a
strong family history of type II diabetes. SSCP variants were observed in 6
of those 12 patients (50%), which cosegregated with diabetes in five
families where DNA from additional members was available. Direct sequencing
identified a 10-bp (base pair) deletion in exon 3; a 33-bp deletion at the
exon 5/intron 5 junction, including the two consensus bases (GT) of the
donor splice site; a nonsense mutation in exon 5 (Arg186-->Stop) in a
Black-African family, which has been identified previously in a Caucasian
family; and three missense mutations: Thr209-->Met209 in exon 6,
Gly261-->Glu261 in exon 7, and Arg36-->Trp36 in exon 2. The missense
mutation in exon 2 was found only in the second and third generation of the
tested family but not in the first. To our knowledge, this is the first
time that a de novo mutation of GCK is reported within a family. All six
families carrying a mutation in GCK were typical MODY and most of their
affected members had a mild form of diabetes. This nonradioactive SSCP
technique may be useful to routinely diagnose glucokinase deficiency, which
is an important cause of hyperglycemia among young type II diabetic
patients.