[Mutation analysis of 35 Wilson's disease pedigrees].

OBJECTIVE: To analyze the features of genetic mutations underlying Wilson's disease and provide prenatal and presymptomatic diagnosis. METHODS: For 35 pedigrees affected with the disease, the exons and exon-intron boundaries of the ATP7B gene were amplified with polymerase chain reaction and subjected to Sanger sequencing. After the genotypes of parents of the probands were determined, prenatal diagnosis were performed through chorionic villus sampling. RESULTS: The overall rate for mutation detection was 92.9%. A total of 24 distinct mutations were detected, which included 7 novel mutations, i.e., c.3871G>A(p.A1291T), c.2593_2594insGTCA, c.2790_2792delCAT, c.3661_3663delGGG, c.3700delG, c.4094_4097delCTGT, and IVS6+1G>A. Three mutations, including R778L (c.2333G>T)(45.7%), A874V (c.2621C>T)(7.1%) and P992L (c.2975C>T)(7.1%), were relatively common. Two presymptomatic patients were detected through familial screening, for whom treatment was initiated. Prenatal genetic diagnosis has verified three healthy fetuses and one carrier. CONCLUSION: In this study the most popular mutation ofATP7B gene is R778L and 7 novel mutations have been identified in this gene. For pedigrees of Wilson's disease, genetic counseling in addition with prenatal and presymptomatic diagnosis should be provided through Sanger sequencing and haplotype analysis.

Noninvasive prenatal testing for Wilson disease by use of circulating single-molecule amplification and resequencing technology (cSMART).

BACKGROUND: Noninvasive prenatal testing (NIPT) for monogenic diseases by use of PCR-based strategies requires precise quantification of mutant fetal alleles circulating in the maternal plasma. The study describes the development and validation of a novel assay termed circulating single-molecule amplification and resequencing technology (cSMART) for counting single allelic molecules in plasma. Here we demonstrate the suitability of cSMART for NIPT, with Wilson Disease (WD) as proof of concept. METHODS: We used Sanger and whole-exome sequencing to identify familial ATP7B (ATPase, Cu(++) transporting, ß polypeptide) gene mutations. For cSMART, single molecules were tagged with unique barcodes and circularized, and alleles were targeted and replicated by inverse PCR. The unique single allelic molecules were identified by sequencing and counted, and the percentage of mutant alleles in the original maternal plasma sample was used to determine fetal genotypes. RESULTS: Four families with WD pedigrees consented to the study. Using Sanger and whole-exome sequencing, we mapped the pathogenic ATP7B mutations in each pedigree and confirmed the proband's original diagnosis of WD. After validation of cSMART with defined plasma models mimicking fetal inheritance of paternal, maternal, or both parental mutant alleles, we retrospectively showed in second pregnancies that the fetal genotypes assigned by invasive testing and NIPT were concordant. CONCLUSIONS: We developed a reliable and accurate NIPT assay that correctly diagnosed the fetal genotypes in 4 pregnancies at risk for WD. This novel technology has potential as a universal strategy for NIPT of other monogenic disorders, since it requires only knowledge of the parental pathogenic mutations.