A novel frameshift mutation induced by an adenosine insertion in the polycystic kidney disease 2 (PKD2) gene.
Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common Mendelian disorders and is genetically heterogeneous. Linkage studies have shown that the majority (approximately 85%) of ADPKD cases are due to mutations in PKD1 on chromosome 16p13.3, while mutations in PKD2 on chromosome 4q21-q23 are thought to account for most of the remaining cases. In this report, we describe the mutation in a large four-generation ADPKD family (TOR-PKD77) which we had mapped to the PKD2 locus by linkage analysis. In this family, we screened for mutations by directly sequencing two nested RT-PCR fragments (PKD2N1 and PKD2N2) that cover approximately 90% of the PKD2 open reading frame. In the affected members, we identified a novel single adenosine insertion (2160InsA) in the PKD2N2 fragment. This mutation occurred in the polyadenosine tract (nt2152-2159) of exon 11 and is predicted to result in a frameshift with premature translation termination of the PKD2 product, polycystin 22, immediately after codon 723. The truncated polycystin 2 is predicted to lack the calcium-binding EF-hand domain and two cytoplasmic domains required for the homodimerization of polycystin 2 with itself and for the heterodimerization of polycystin 2 with polycystin 1.
Pei
Y
Y
Department of Medicine, Toronto Hospital, Ontario, Canada. ypei@torhosp.toronto.on.ca
Wang
K
K
Kasenda
M
M
Paterson
A D
AD
Liang
Y
Y
Huang
E
E
Lian
J
J
Rogovea
E
E
Somlo
S
S
St George-Hyslop
P
P
D000241:Adenosine / Q000235:genetics; D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D002894:Chromosomes, Human, Pair 4 / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D005091:Exons; D005260:Female; D016368:Frameshift Mutation; D008040:Genetic Linkage; D005838:Genotype; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D008875:Middle Aged; D008958:Models, Molecular; D009693:Nucleic Acid Hybridization; D010375:Pedigree; D016891:Polycystic Kidney, Autosomal Dominant / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D050396:TRPP Cation Channels
D000241:Adenosine; D017931:DNA Primers; D008565:Membrane Proteins; D050396:TRPP Cation Channels