Genomic characterization of the human peptidyl-prolyl-cis-trans-isomerase,mitochondrial precursor gene: assessment of its role in familial dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a common cause of morbidity and mortality, with >30% of cases being inherited. In one family with autosomal dominant f amilial dilated cardiomyopathy (FDCM), we localized the gene to the region of 10q21-10q23 and have performed candidate positional gene cloning. The pe ptidyl-prolyl-cis-trans-isomerase, mitochondrial precursor (PPIF: previousl y known as cyclophilin 3) is a protein that is part of the mitochondrial pe rmeability transition pore, the activation of which is involved in the indu ction of necrotic and apoptotic cell death. Since it is encoded by a gene l ocated within this FDCM critical region, PPIF was considered a potential ca ndidate gene for FDCM. In order to screen patient genomes for evidence of d isease-associated mutations, the genomic organization of this gene was dete rmined. BAC libraries were screened by PCR, using primers designed from the published cDNA sequence, and positive clones were identified. This enabled the gene to be further localized to between the CEPH markers D10S1777 and D10S201. The DNA from a BAC clone was digested and subcloned into pUC18. Fo llowing identification of a subclone by whole-cell PCR, the gene was charac terized by DNA sequencing; five introns were identified, and me sequences o f the intron-exon boundaries were characterized. Additionally, 450 bp of DN A sequence upstream of the published cDNA were obtained and a potential tra nscription initiation sire and promoter sequence were identified. DNA analy sis of the entire PPIF coding region (including the intron-exon boundaries) of two affected and one unaffected family member revealed no mutations, th erefore excluding this gene as the cause of FDCM in this family.