OBJECTIVE - To analyze the association between human leukocyte antigen (HLA) and insulin-dependent diabetes mellitus (IDDM) in the Egyptian population for the first time and, thus, to determine the frequency of risk- associated alleles identified by a genomic HLA class II typing. Egyptians are genetically classified as North Africans and considered to be between Caucasoids and Africans (closer to Caucasoids). RESEARCH DESIGN AND METHODS - HLA class II typing was performed for 50 IDDM patients and 50 healthy control subjects by a restriction fragment-length polymorphism (RFLP) technique. The analysis of position 57 of the DQB1 molecules was conducted by polymerase chain reaction and specific sequence oligonucleotide hybridization. RESULTS - The frequency of DRB1*0301-DRB3*0201-DQA1*0501- DQB1*0201 haplotype was 43.9% in the IDDM patients and 7.1% in the control subjects (P < 0.00001), reflecting the increased prevalence of DQA1*0501 susceptibility allele coding for arginine (Arg) in position 52 and DQB1*0201 susceptibility allele noncoding aspartic acid (Asp) at position 57. Alleles DQB1*0601 and 0603, both carrying Asp at position 57 of the β-chain, and DQA1*0103, encoding a non-Arg 52 α-chain, were significantly decreased among the IDDM patients. The presence of four susceptibility residues (two DQA1 Arg 52+ and two DQB1 Asp 57-) conferred the highest relative risk at 20.2. On the other hand, homozygous genotypes for DQA1 non-Arg 52 and DQB1 Asp 57 were found only in the control group. CONCLUSIONS - IDDM susceptibility and resistance in the Egyptian population is strongly associated with the expressed DQ α- and β-heterodimers in a dose-effective manner, as already defined in many different ethnic groups.
Human leukocyte antigen class II polymorphisms and genetic susceptibility of IDDM in Egyptian children
Curtoni E. S.;Amoroso A.
1994-01-01
Abstract
OBJECTIVE - To analyze the association between human leukocyte antigen (HLA) and insulin-dependent diabetes mellitus (IDDM) in the Egyptian population for the first time and, thus, to determine the frequency of risk- associated alleles identified by a genomic HLA class II typing. Egyptians are genetically classified as North Africans and considered to be between Caucasoids and Africans (closer to Caucasoids). RESEARCH DESIGN AND METHODS - HLA class II typing was performed for 50 IDDM patients and 50 healthy control subjects by a restriction fragment-length polymorphism (RFLP) technique. The analysis of position 57 of the DQB1 molecules was conducted by polymerase chain reaction and specific sequence oligonucleotide hybridization. RESULTS - The frequency of DRB1*0301-DRB3*0201-DQA1*0501- DQB1*0201 haplotype was 43.9% in the IDDM patients and 7.1% in the control subjects (P < 0.00001), reflecting the increased prevalence of DQA1*0501 susceptibility allele coding for arginine (Arg) in position 52 and DQB1*0201 susceptibility allele noncoding aspartic acid (Asp) at position 57. Alleles DQB1*0601 and 0603, both carrying Asp at position 57 of the β-chain, and DQA1*0103, encoding a non-Arg 52 α-chain, were significantly decreased among the IDDM patients. The presence of four susceptibility residues (two DQA1 Arg 52+ and two DQB1 Asp 57-) conferred the highest relative risk at 20.2. On the other hand, homozygous genotypes for DQA1 non-Arg 52 and DQB1 Asp 57 were found only in the control group. CONCLUSIONS - IDDM susceptibility and resistance in the Egyptian population is strongly associated with the expressed DQ α- and β-heterodimers in a dose-effective manner, as already defined in many different ethnic groups.
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