AUTOSOMAL-DOMINANT POLYCYSTIC KIDNEY-DISEASE (ADPKD) IN AN ITALIAN FAMILY CARRYING A NOVEL NONSENSE MUTATION AND 2 MISSENSE CHANGES IN EXON-44 AND EXON-45 OF THE PKD1 GENE

Sixty-seven Italian patients with autosomal dominant polycystic kidney disease (ADPKD) were screened for mutations in the 3' unique region o f the PKD1 gene, using heteroduplex DNA analysis. Novel aberrant bands were detected in 3 patients from the same family. DNA sequencing show ed a C to T transition in exon 44 (C12269T), resulting in a premature stop codon (R4020X), predicted to impair the synthesis of the putative intracytoplasmic C-terminus tail of the PKD1 protein, polycystin. The mutation also generates a novel DdeI restriction site, and the abnorm al restriction pattern was observed both on genomic DNA and on cDNA fr om the affected relatives, indicating that this is indeed the pathogen etic molecular lesion. Reverse transcriptase-polymerase chain reaction (RT-PCR) performed on lymphocyte mRNA showed that the mutant transcri pt is normally present and stable. No aberrantly spliced mRNAs were de tected. Interestingly, the mutant PKD1 chromosome in this family also bears two missense mutations downstream (A12341G and C12384T), not fou nd in the other ADPKD families studied. (C) 1996 Wiley-Liss, Inc.