Analysis of missense variants in the PKHD1-gene in patients with autosomal recessive polycystic kidney disease (ARPKD).
Autosomal recessive polycystic kidney disease (ARPKD) is a severe form of polycystic kidney disease characterized by enlarged kidneys and congenital hepatic fibrosis. Given the poor prognosis for the majority of children with the severe perinatal ARPKD phenotype, there is a regular request for prenatal testing. ARPKD is caused by mutations in the polycystic kidney and hepatic disease 1 (PKHD1) gene, which consists of 86 exons that are variably assembled into a number of alternatively spliced transcripts. The longest transcript, comprising 67 exons, encodes the protein fibrocystin/polyductin. We have set up mutation analysis by direct sequencing of these 67 exons. In 39 mainly Dutch families we identified: 11 nonsense mutations, 15 deletions/insertions, 5 splice site mutations, and 39 missense mutations. To classify missense variants we combined evolutionary conservation, using the human, chimpanzee, dog, mouse, chicken and frog Pkhd1 sequences, with the Grantham score for chemical differences. Thirty-three missense mutations were considered pathogenic and seven were classified as rare, probably pathogenic variants. In addition to sequence analysis, multiplex ligation-dependent probe amplification (MLPA) was used to identify multiple exon deletions. However, no large deletions in the PKHD1 gene were identified. In 31 index patients two mutations were found, in 6 patients one mutation was found, leading to a mutation detection rate of 87%. The analysis of amino acid conservation as well as applying the Grantham score for chemical differences allowed us to determine the pathogeneity for nearly all new missense mutations and thus proved to be useful tools to classify missense variants.
Losekoot
Monique
M
Center for Human and Clinical Genetics, Sylvius Laboratory, Leiden University Medical Center, Wassenaarseweg 72, 2333, AL, Leiden, The Netherlands.
Haarloo
Cathleen
C
Ruivenkamp
Claudia
C
White
Stefan J
SJ
Breuning
Martijn H
MH
Peters
Dorien J M
DJ
D000595:Amino Acid Sequence; D000818:Animals; D001001:Anura; D002645:Chickens; D002648:Child; D002675:Child, Preschool; D004285:Dogs; D005091:Exons; D005260:Female; D006801:Humans; D007668:Kidney / Q000473:pathology; D022521:Ligase Chain Reaction; D008103:Liver Cirrhosis / Q000235:genetics / Q000473:pathology; D008297:Male; D051379:Mice; D016254:Mutagenesis, Insertional; D020125:Mutation, Missense; D009426:Netherlands; D002679:Pan troglodytes; D017044:Polycystic Kidney, Autosomal Recessive / Q000235:genetics* / Q000473:pathology; D011379:Prognosis; D011956:Receptors, Cell Surface / Q000235:genetics*; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
C451750:PKHD1 protein, human; D011956:Receptors, Cell Surface