Intermediate expansions of a GAA repeat in the frataxin gene are not associated with type 2 diabetes or altered glucose-induced beta-cell function in Danish Caucasians.
A variable expansion of a GAA repeat is present in the first intron of the frataxin gene, also termed FRDA1 or X25. Long repeat lengths (>66 repeats) are present in patients with Friedreich's ataxia, while an intermediate expansion (10-66 repeats) has recently been reported to be highly associated with type 2 diabetes. Using a polymerase chain reaction-based assay, we found that 32.4% (95%CI 29.9-34.9) of 636 Danish Caucasian type 2 diabetic patients were carriers of an intermediate expansion, whereas the frequency was 30.4% (26.4-34.4) among 224 matched glucose-tolerant control subjects (P = 0.6). In the control subjects, the values of serum insulin and C-peptide responses during an oral glucose tolerance test were similar between the 69 carriers and 155 noncarriers. Furthermore, we investigated a possible relationship between expansions of the FRDA1 gene and glucose-induced beta-cell function in 338 young Caucasians (33.7% [30.1-37.3] carriers) and in 215 glucose-tolerant subjects (31.0% [26.6-35.4] carriers) with a type 2 diabetic parent. In neither population did the carriers differ from noncarriers according to values of fasting plasma glucose, serum insulin, or C-peptide, acute serum insulin, or C-peptide responses after intravenous glucose. In conclusion, intermediate expansion of the frataxin trinucleotide repeat is not associated with type 2 diabetes or altered glucose-induced insulin secretion in Danish Caucasians.
Dalgaard
L T
LT
Steno Diabetes Center, Glostrup University Hospital, Denmark.
Hansen
T
T
Urhammer
S A
SA
Clausen
J O
JO
Eiberg
H
H
Pedersen
O
O
D000328:Adult; D003718:Denmark; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D033862:Iron-Binding Proteins; D007515:Islets of Langerhans / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D019680:Trinucleotide Repeat Expansion / Q000502:physiology*; D044465:White People / Q000235:genetics*; D000096923:Frataxin
D005947:Glucose; D033862:Iron-Binding Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D000096923:Frataxin