Genetic, Physical, and Transcript Map of the fld Region on Mouse Chromosome 12

The fatty liver dystrophy (fld) mutation is manifested in abnormalities of lipid and glucose metabolism and peripheral neuropathy. To identify the gene affected by this mutation, we generated a genetic map of the fld region on chromosome 12 by the analysis of F2 offspring from an intersubspecific cross between strains BALB/cByJ-fld and CAST/EiJ. The results localize fld to the 0.42-cM interval between the microsatellite markers D12Mit170 and D12Mit184. A contig of YACs and BACs covering the nonrecombinant genomic region has been constructed and used for the identification of genes. Expressed sequence tag mapping and exon trapping identified three transcripts within the critical interval: Ctla2b, which encodes a cysteine protease inhibitor, and mouse homologs of KIAA0188 and KIAA0575, two long human transcripts of unknown function. Expression analysis revealed that Kiaa0188 is expressed in wildtype but not in fld liver, implicating this gene as a candidate for harboring the fld mutation.