Mitochondrial gene mutations and type 2 diabetes in Chinese families.
BACKGROUND
Numerous mitochondrial DNA mutations are significantly correlated with development of diabetes. This study investigated mitochondrial gene, point mutations in patients with type 2 diabetes and their families.


METHODS
Unrelated patients with type 2 diabetes (n = 826) were randomly recruited; unrelated and nondiabetic subjects (n = 637) served as controls. The clinical and biochemical data of the participants were collected. Total genome was extracted from peripheral leucocytes. Polymerase chain reaction, restriction fragment length polymorphism (PCR-RFLP) and cloning techniques were used to screen mitochondrial genes including np3316, np3394 and np3426 in the ND1 region and np3243 in the tRNA(Leu(UUR)).


RESULTS
In 39 diabetics with one or more mitochondrial gene point mutations, the prevalence (4.7%, 39/826) of mtDNA mutations was higher than that (0.7%, 5/637) in the controls. The identical mutation was found in 23 of 43 tested members from three pedigrees. Affected family members presented with variable clinical features ranging from normal glucose tolerance to impaired glucose tolerance (IGT) (n = 2), impaired fasting glucose (IFG) (n = 1) to type 2 diabetes (n = 13) with 3 family members suffering from hearing loss.


CONCLUSIONS
Type 2 diabetes in China is associated with several mitochondrial gene mutations. Aged patients with diabetic family history had a higher prevalence of mutation and various clinical pictures. Mitochondrial gene mutation might be one of the genetic factors contributing to diabetic familial clustering.
Li
Ming-zhen
MZ
Department of Endocrinology, Health Ministry Key Laboratory of Hormones and Development, Metabolic Disease Hospital of Tianjin Medical University, Tianjin 300070, China.
Yu
De-min
DM
Yu
Pei
P
Liu
De-min
DM
Wang
Kun
K
Tang
Xin-zhi
XZ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D002681:China; D004272:DNA, Mitochondrial / Q000235:genetics*; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length
D004272:DNA, Mitochondrial