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The diabetes-prone BB rat carries a frameshift mutation in Ian4, a positional candidate of Iddm1.

Authors: Hornum, L  Romer, J  Markholst, H 
Citation: Hornum L, etal., Diabetes 2002 Jun;51(6):1972-9.
Pubmed: (View Article at PubMed) PMID:12031988

Diabetes-prone (DP) BB rats spontaneously develop insulin-dependent diabetes resembling human type 1 diabetes. They also exhibit lifelong T-cell lymphopenia. Functional and genetic data support the hypothesis that the gene responsible for the lymphopenia, Lyp, is also a diabetes susceptibility gene, named Iddm1. We constructed a 550-kb P1-derived artificial chromosome contig of the region. Here, we present a corrected genetic map reducing the genetic interval to 0.2 cM and the physical interval to 150-290 kb. A total of 13 genes and six GenomeScan models are assigned to the homologous human DNA segment on HSA7q36.1, 8 of which belong to the family of immune-associated nucleotides (Ian genes). Two of these are orthologous to mouse Ian1 and -4, both excellent candidates for Iddm1. In normal rats, they are expressed in the thymus and T-cell regions of the spleen. In the thymus of lymphopenic rats, Ian1 exhibits wild-type expression patterns, whereas Ian4 expression is reduced. Mutational screening of their coding sequences revealed a frameshift mutation in Ian4 among lymphopenic rats. The mutation results in a truncated protein in which the COOH-terminal 215 amino acids-including the anchor localizing the protein to the outer mitochondrial membrane-are replaced by 19 other amino acids. We propose that Ian4 is identical to Iddm1.


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RGD Object Information
RGD ID: 633092
Created: 2003-08-29
Species: All species
Last Modified: 2004-05-25
Status: ACTIVE


RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.