Mapping of caspase-2 in the rat and its exclusion as a candidate gene for lymphopenia

Caspase-2 is a member of the caspase family of cystein proteases involved i n programmed cell death or apoptosis. Functional and genetic data suggest i t as a candidate gene for lymphopenia (Lyp)-a susceptibility gene for rat d iabetes-which is responsible for the T-cell lymphopenia in the diabetes-pro ne BE rat, Firstly, there is a higher frequency of apoptosis among recent t hymic emigrants in the diabetes-prone BE rat than in the non-lymphopenic di abetes-resistant BE rat. Secondly, caspase-2 maps close to Tcrb, on mouse C hromosome (Chr) 6, while Lyp is closely linked to Tcrb on the homologous ra t Chr 4. In this paper, we report genetic fine-positioning and radiation hy brid mapping of caspase-2 in the rat. Both methods positioned caspase-2 to rat Chr 4 between markers Prss1 and D4Mit5. Since Lyp maps distally to D4Mi t5, between markers D4Rat75 and Npy, we exclude caspase-2 as a candidate ge ne for Lyp.