Influence of gender and age at onset on the HLA associations in Chinese with insulin-dependent diabetes mellitus.

IDDM in Singaporean Chinese was associated with HLA B58, DRB1*0301, DQB1*0201, and joint occurrences of DRB1*0301/*0901 and DRB1*0301/*04. Of the DR4s the frequencies of DRB1*0401, *0404, and *0405 were higher and *0406 was lower in patients compared to controls. DRB1*0301/*0901 was observed mainly in female patients and the frequency showed an inverse relationship with age at onset, whereas DRB1*0301/*04 was observed mainly in male patients and also showed an inverse relationship with age at onset. DRB1*1202 showed an increasing frequency with age at onset. IDDM patients had a higher frequency of homozygous NAsp57 DQ beta chains and a lower frequency of homozygous Asp57 DQ beta chains compared to controls, especially in younger onset patients.