A complete mutation screen of PKHD1 in autosomal-recessive polycystic kidney disease (ARPKD) pedigrees.
BACKGROUND
Autosomal-recessive polycystic kidney disease (ARPKD) is an important neonatal nephropathy characterized by fusiform dilation of collecting ducts, congenital hepatic fibrosis, and in some cases Caroli's disease. The ARPKD gene, PKHD1, has recently been identified. Herein we describe an effective method for PKHD1 mutation screening and the results from analysis of a novel ARPKD cohort.


METHODS
The coding region of PKHD1 was amplified as 79 fragments and analyzed for base pair changes by denaturing high-performance liquid chromatography (DHPLC). Forty-seven ARPKD and 14 pedigrees with congenital hepatic fibrosis and/or Caroli's disease, were screened for PKHD1 mutations.


RESULTS
Thirty-three different mutations were detected on 57 alleles (51.1% ARPKD, 32.1% congenital hepatic fibrosis/Caroli's disease). In the 22 pedigrees where both mutations were identified, two were homozygous for 9689delA and the remainder were compound heterozygotes; a combination of truncating, missense and splicing changes. Patients with two truncating mutations all died in the perinatal period. Two frequent truncating mutations were identified: 9689delA (9 alleles) and 5896insA (8 alleles) plus some more common missense changes; haplotype analysis indicated most were ancestral mutations.


CONCLUSIONS
DHPLC has been established as a rapid mutation screening method for ARPKD. The mutation detection rate was high in severely affected patients (85%), lower in those with moderate ARPKD (41.9%), and low, but significant, in adults with congenital hepatic fibrosis/Caroli's disease (32.1%). The prospects for gene-based diagnostics are complicated by the large gene size, marked allelic heterogeneity, and clinical diversity of the ARPKD phenotype. Identification of some common mutations, especially in specific populations, will aid mutation screening.
Rossetti
Sandro
S
Division of Nephrology, Mayo Clinic, Rochester, Minnesota 55905, USA.
Torra
Roser
R
Coto
Eliecer
E
Consugar
Mark
M
Kubly
Vickie
V
Málaga
Serafin
S
Navarro
Mercedes
M
El-Youssef
Mounif
M
Torres
Vicente E
VE
Harris
Peter C
PC
D000293:Adolescent; D000328:Adult; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D015331:Cohort Studies; D004252:DNA Mutational Analysis; D005260:Female; D005820:Genetic Testing / Q000379:methods*; D006239:Haplotypes; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D020125:Mutation, Missense; D010375:Pedigree; D017044:Polycystic Kidney, Autosomal Recessive / Q000235:genetics*; D011956:Receptors, Cell Surface / Q000235:genetics*
C451750:PKHD1 protein, human; D011956:Receptors, Cell Surface