A specific haplotype at the INS/TH loci confers high susceptibility to IDDM
- Harvard Medical School, Boston, MA (United States)
Polymorphism at the insulin locus (INS) have consistently been found to be associated with insulin-dependent diabetes mellitus (IDDM). We investigated whether a combined analysis of the INS locus with the 5{prime} flanking tyrosine hydroxylase (TH) locus increases the specificity of this association. A group of 308 Caucasians (201 IDDM CASES and 107 non-diabetic CONTROLS) were genotyped for the two-allele markers, INS/1127PstI and TH/Rsal, by PCR-DGGE. INS/1127PstI allele 2 was more common in CASES than CONTROLS (0.84 vs. 0.68, p<0.0001). The relative risk of IDDM for homozygotes for this allele (2/2) was 3.3 in comparison with the other genotypes (95% CI 2.0-5.3). Similarly, homozygotes for allele 2 of TH/RsaI, which is in moderate linkage disequilibrium with INS/1127PstI ({Delta} = 0.45), had a relative risk of IDDM of 2.5 (1.6-4.2). By haplotyping individuals for the two markers, INS/1127PstI 2/2 genotypes were subdivided on the basis of their INS-TH haplotypes. The excess of INS/1127PstI 2/2 homozygotes in IDDM cases was mainly contributed by homozygotes for the INS-TH haplotype 22. Thus, among hapotypes carrying INS/1127 PstI allele 2, the INS-TH 22 haplotype is a more specific marker of IDDM risk than the INS-TH 21 haplotype. The association of the INS-TH 22/22 genotype with IDDM was independent of HLA, being similar among carriers and non-carriers of IDDM-predisposing DQ{beta} alleles 0302 and 0201-DR3.
- OSTI ID:
- 134200
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0936
- 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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