Clinical characteristics of mutation carriers in a large family with glucokinase diabetes (MODY2).
OBJECTIVE
To investigate the prevalence and clinical characteristics of heterozygotes of the glucokinase gene mutations G264S and IVS8+2 in the extended pedigree of two patients with permanent neonatal diabetes as a result of glucokinase deficiency (IVS8+2 homozygosity and IVS8+2/G264S compound heterozygosity).


METHODS
Eighty-eight first, second and third degree family members of the two patients with permanent neonatal diabetes were genotyped. Clinical, laboratory and historical data were collected via chart reviews.


RESULTS
Thirty-one IVS8+2 and three G264S heterozygotes were identified. Of these, 18/34 (52.9%) had diabetes and 9/34 (26.5%) impaired fasting glucose (IFG), compared with 1/54 (1.9%) with diabetes and 2/54 (3.7%) with IFG in the non-carrier group. Odds ratio for heterozygotes was 70.4 (95% CI 16.9-293.5 and P < 0.001). Mean body mass index of heterozygotes (> 18 years of age) who had diabetes was 27.1 +/- 2.66, compared with 23.18 +/- 4.72 for heterozygotes with normal glucose levels (P < 0.05). While none of the non-carrier women had gestational diabetes, eight of the 10 heterozygotes developed gestational diabetes. Inheritance of a glucokinase mutation by the fetus from a carrier mother resulted in a significant reduction in birthweight (3600 +/- 570 vs. 2970 +/- 390 grams, P < 0.05).


CONCLUSIONS
These data support the association between carriage of GCK gene mutations, G264S and IVS8+2, and the development of diabetes, impaired fasting glucose and reduced birthweight. Moreover, in heterozygotes, a clear correlation between body mass index and the development of diabetes was observed. These findings underline the need for surveillance and prevention in individuals at risk.
Shehadeh
N
N
Pediatric Diabetes Unit and Department of Human Genetics, Meyer Children's Hospital of Haifa, Faculty of Medicine, Technion, Haifa, Israel. n_shehadeh@rambam.health.gov.il
Bakri
D
D
Njølstad
P R
PR
Gershoni-Baruch
R
R
D000293:Adolescent; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D003920:Diabetes Mellitus / Q000235:genetics*; D005260:Female; D005941:Glucokinase / Q000235:genetics*; D005951:Glucose Tolerance Test; D006579:Heterozygote; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*
D001786:Blood Glucose; D005941:Glucokinase