The possible role of genomic imprinting at HLA-DQ/DR region in the pathogenesis of insulin-dependent diabetes mellitus
- Univ. School of Medicine, Tokyo (Japan); and others
Insulin-dependent diabetes mellitus (IDDM) is an autoimmune endocrinopathy that often develops with anti glutamic acid decarboxylase autoantibody (GAD-Ab). Accumulated data indicate that specific alleles with HLA-DQA1{sup *}0301 strongly associate with IDDM so that its susceptible gene is localized at HLA class II DQ/DR region. The mode of transmission, however, remains still unclear. To investigate the possibility of involvement of genomic imprinting at the susceptible gene in IDDM, we conducted pedigree analysis of 16 IDDM probands who are positive for GAD-Ab and their first-degree relatives consisting of 14 mothers, 11 fathers and 11 sibs. The GAD-Ab was measured with RIA (cut off = 5 U/ml), and genotypes of DQA1 and DRB1 loci were determined with PCR-RFLP method. Of the observed 16 families, one had an affected brother who developed IDDM and was positive for GAD-Ab (144 U/ml), but the remaining 15 were simplex families. Except for the affected brother, all relatives appeared to be negative for GAD-Ab. DQA1 genotyping showed that 11 probands were homozygotes of high-risk DQA1{sup *}0301, but the five probands were heterozygous with DQA1{sup *}0301/X who were informative for the parental origin of DQA1{sup *}0301 allele. Pedigree analyses revealed that all DQA1{sup *}0301 alleles of the five affected heterozygotes were transmitted from their mothers. We next analyzed segregation pattern of DQA1-DRB1 haplotypes and found that the affected brother shared the same maternally transmitted allele with the proband. Further haplotype analysis indicated that the informative six unaffected sibs did not share the maternally transmitted DQA1{sup *}0301 alleles with their probands. From the exclusive association with maternally transmitted DQA{sup *}0301 alleles, we propose the hypothesis that maternal transmission of {open_quotes}affected alleles{close_quotes} are required for the development of IDDM with the mechanism of genomic imprinting at the HLA-DQ/DR region.
- OSTI ID:
- 134315
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-1048
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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