Prevalence of HNF1A (MODY3) mutations in a Norwegian population (the HUNT2 Study).
OBJECTIVE
Previous reports have indicated that maturity-onset diabetes of the young (MODY) caused by hepatocyte nuclear factor 1A (HNF1A) mutations (MODY3) is the most common MODY subtype in Northern Europe, but population-based prevalence estimates are lacking. We sought to determine the prevalence of HNF1A-MODY in diabetic subjects of a defined Norwegian population (the HUNT2 Study).


METHODS
Of the 1972 diabetic HUNT2 subjects, we identified a subgroup of 43 suspected MODY cases based on information on family history, disease onset and anti-glutamic acid decarboxylase autoantibody status. These cases were considered a discovery group for HNF1A mutations and underwent full DNA sequencing. Subsequently, the entire cohort of diabetic HUNT2 subjects was screened for three selected HNF1A mutations. Possible founder effects were examined using the Norwegian MODY Registry.


RESULTS
Three subjects from the discovery group harboured HNF1A mutations. Two subjects had the previously described R229Q mutation, one had a novel S6N alteration, whereas the HNF1A hot-spot mutation P291fsinsC was not identified. Genotyping the cohort of diabetic HUNT2 subjects identified five additional R229Q-positive subjects. Microsatellite analysis performed for all R229Q-positive probands of the Norwegian MODY Registry and those found in the HUNT2 population revealed that 17 of 18 (94%) had genotypes consistent with a common haplotype.


CONCLUSIONS
Clinical MODY criteria were fulfilled in 2.2% of diabetic HUNT2 subjects. The minimum prevalence of HNF1A-MODY among diabetic HUNT2 subjects was 0.4%. Because of founder effects, registry-based prevalence studies probably need to be very large and they should also include prospectively collected phenotypes and extensive mutation screening to establish the true prevalence of MODY.
Section for Pediatrics, Department of Clinical Medicine, University of Bergen, Bergen, Norway.
S A
SA
Eide
H
H
Raeder
S
S
Johansson
K
K
Midthjell
O
O
Søvik
P R
PR
Njølstad
A
A
Molven
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology / Q000235:genetics*; D004812:Epidemiologic Methods; D005260:Female; D051538:Hepatocyte Nuclear Factor 1-alpha / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016296:Mutagenesis / Q000235:genetics*; D009664:Norway / Q000453:epidemiology
D051538:Hepatocyte Nuclear Factor 1-alpha