Haemochromatosis gene mutations Cys282Tyr and His63Asp are not increased in Type 2 diabetic patients compared with the Canterbury (New Zealand) general population

Genetic predisposition to haemochromatosis may be an important aetiological factor in some cases of Type 2 diabetes. Our aim was therefore to test the hypothesis that the haemochromatosis gene mutations Cys282Tyr and His63Asp are more prevalent in Type 2 diabetic patients compared with the Canterbur y, New Zealand general population. We studied 230 consecutive patients refe rred to the Diabetes Services with age greater than or equal to 30 years an d considered to have Type 2 diabetes. DNA was extracted from whole blood an d amplified by polymerase chain reaction prior to restriction fragment leng th polymorphism analysis. The frequency of the mutations was compared with that observed previously in 1064 subjects from the Canterbury general popul ation by chi(2) testing. Iron was measured by a colorimetric method, transf errin by rate nephelometry and ferritin by immunoassay. There were 2/230 (0 .8%) Cys282Tyr homozygous subjects in the diabetic group compared with 5/10 64 (0.5%) NS in the general population. Although there was a trend to lower incidence of Cys282Tyr heterozygosity in the diabetic group, there was no significant difference for any of the six genotype frequencies between the two groups. Haemochromatosis gene mutations Cys282Tyr and His63Asp are ther efore not increased in Type 2 diabetics compared with the general populatio n. Transferrin saturation was a sensitive marker (100%) of genetic haemochr omatosis, although ferritin had low specificity (77.8%). Genetic susceptibi lity to haemochromatosis is not an important aetiological factor for diabet es, and targeted screening of diabetic patients for haemochromatosis is not indicated. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.