Contribution of the absence of aspartic acid at position 57 of the HLA-DQ beta chain to predisposition to insulin-dependent diabetes mellitus in a southern Chinese population.
OBJECTIVE
To investigate the association of the absence or presence of aspartic acid at position 57 of the HLA-DQ beta chain (NA or A) with susceptibility or resistance to insulin-dependent diabetes mellitus (IDDM) in a Southern Chinese population.


METHODS
Sixty-nine IDDM patients and 47 healthy controls in a Southern Chinese population were HLA-DQB1 genotyped by one-step sequence specific polymerase chain reaction (ssPCR).


RESULTS
The frequencies of NA and A were 64.5% and 35.5% in the IDDM patients, and 40.4% and 59.6% in the control subjects respectively (RR for NA was 2.68, P < 0.01). The frequencies of NA/NA, NA/A and A/A phenotypes were 47.8%, 33.3% and 18.8% in the IDDM patients, and 31.9%, 17.0% and 51.1% in the controls respectively (P < 0.01). The frequency of A/A phenotype was significantly lower in the IDDM patients than in the control subjects (RR = 0.22, P < 0.01). DQB1* 0302 and DQB1* 0201 were more frequent in IDDM patients than in control subjects. The younger the age of IDDM onset, the higher the allele frequencies of DQB1* 0201 and DQB1* 0302.


CONCLUSIONS
The present study suggests that the NA confers the susceptibility to IDDM, while the A confers the protection against IDDM in patients of Southern Chinese origin. These associations are more clearcut in childhood-onset IDDM patients.
Department of Endocrinology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University of Medical Sciences, Guangzhou 510120, China.
S
S
Zhang
H
H
Cheng
Z
Z
Fu
G
G
Zhong
T
T
Yan
D000293:Adolescent; D000328:Adult; D000483:Alleles; D044466:Asian People; D001224:Aspartic Acid / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006683:HLA-DQ Antigens / Q000235:genetics*; D059866:HLA-DQ beta-Chains; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype
D006683:HLA-DQ Antigens; D059866:HLA-DQ beta-Chains; C069051:HLA-DQB1 antigen; D001224:Aspartic Acid