OBJECTIVETo investigate the genetic and clinical features of mutations and sequence variations of the transcription factor 1 gene (TCF1, HNF-1A) in Chinese with familial early-onset and/or multiplex diabetes mellitus.

METHODSAll ten exons of the TCF1 gene were screened, including exon and intron junctions, by direct sequencing method in 341 unrelated Chinese subjects, including 80 healthy controls and 261 probands of early-onset and/or multiplex diabetes pedigrees.

RESULTSFive mutations were found in all. Four of the 5 different TCF1 mutations were newly identified novel mutations(T82M, Q130H, G253G, P353fsdelACGGGCCTGGAGC), mean body mass index of mutation carriers was 21.9 kg/m (2), and insulin secretion was impaired in the mutation carriers. In this study, the maturity-onset diabetes of the young type III (MODY3) only accounted for 3% of Chinese early-onset diabetes. Moreover, eleven substitutions were identified in 261 probands. Of them, three variants IVS1-8 (G-->A), IVS1 -128 (T-->G ) and IVS2+21 (G-->A) were not observed in 80 healthy controls and one of them IVS1-8 (G-->A) was not reported previously and the two promoter variants co-segregated with diabetes.

CONCLUSIONTCF1 gene is not a common cause of early-onset and/or multiplex diabetes among Chinese patients.