Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.14.16.2 (tyrosine hydroxylase)
 14,760 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The gene region on chromosome 11p15.5 known to be involved in insulin-dependent diabetes mellitus (IDDM) susceptibility was recently mapped to a 4.1-kilobase region including the insulin gene. The region contains 10 candidate polymorphisms that are in strong linkage disequilibrium. By genotyping 7 of these 10 polymorphisms and the tyrosine hydroxylase microsatellite in Finnish Caucasoid IDDM patients and control subjects, we demonstrate that many of the polymorphisms found to be associated with IDDM in other Caucasoid populations do not show any association in this Finnish population. Of the polymorphisms typed, only those at -23 Hph I and the variable number of tandem repeats (VNTR) sites confer significant relative risk. Furthermore, we have demonstrated that the -23 Hph I polymorphism cannot explain the association. Comparison of the genotypic patterns observed here and previously suggests that the VNTR is the most likely candidate for IDDM2. The VNTR is located adjacent to defined regulatory DNA sequences affecting insulin gene expression, which suggests a possible effect on expression of insulin or one of the neighboring genes, tyrosine hydroxylase or insulin-like growth factor 2.
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PMID:Insulin gene region-encoded susceptibility to IDDM maps upstream of the insulin gene. 778 24

An inconsistency has come to light between the conclusion of Lucassen et al. that IDDM2 (11p15.5) must lie within a 4.1 kilobase (kb) segment at the insulin (INS) locus and their own data showing statistically significant associations between insulin-dependent diabetes mellitus (IDDM) and markers beyond the boundaries of that segment. We present data from an independent study of 201 IDDM patients and 107 non-diabetic control subjects that also show significant association with a marker 5' of the INS locus. Patients and control subjects were genotyped at INS/+ 1140 A/C (a surrogate for the variable number tandem repeat (VNTR) polymorphism in the regulatory part of the INS gene) and a marker 5' of the tyrosine hydroxylase (TH) gene, TH/pINS500-RsaI, making it 10 kb 5' of the VNTR. Homozygotes for INS/ + 1140 allele '+' were significantly more frequent among IDDM patients than among control subjects (73 vs 45%, p < 0.001) giving an odds ratio of 3.3 (95% confidence interval (CI): 2.0-5.3). A very similar association was found for homozygotes for the TH/RsaI allele '+' (53 vs 31%, p < 0.001) giving an odds ratio of 2.6 (95%CI 1.6-4.2). By multilocus analysis, the TH/RsaI allele '+' identified a subset of INS/ + 1140 alleles '+' haplotypes that are more specifically associated with IDDM (odds ratio = 5.4, 95%CI 2.9-10.4) than allele + 1140 '+' as a whole. In conclusion, the segment of chromosome 11 that is associated with IDDM spans, at least, the INS and TH loci. No legitimate claim can be made that IDDM2 corresponds to the VNTR polymorphism at the INS locus until the correct boundaries for IDDM2 have been defined and other loci within them have been excluded as determinants of IDDM.
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PMID:Diabetes susceptibility at IDDM2 cannot be positively mapped to the VNTR locus of the insulin gene. 873 20