Genetic analysis and prenatal diagnosis for a family with Niemann-Pick disease type C / 中华围产医学杂志

ABSTRACT

Objective To analyze gene mutations of a Niemann-Pick disease type C (NPC) proband,and carry out prenatal diagnosis for the family.Methods The coding regions of NPC1 gene in the proband (late-infantile form) and white blood cell (WBC) in peripheral blood of its parents were amplified by polymerase chain reaction and direct DNA sequencing in both directions was performed.The sequencing results were compared with human NPC1 gene sequence (NM_000271) in GenBank,and sequences of mutated exons were determined.Direct sequencing was used on 50 normal Chinese individuals' DNA samples (control) to exclude mutation's single nucleotide polymorphism (SNP).An inter-species alignment of homologous NPC1 proteins was performed using ClustalX 1.81 software.During the second pregnancy of the proband's mother,the amniotic fluid was obtained at 18 weeks of gestation and the amniocytes were cultured for gene mutation analysis.Neonate's DNA of WBC in peripheral blood was also extracted for NPC1 gene analysis.Results Mutation analysis of NPC1 gene revealed two novel heterozygous mutations (c.2284-2287 delCTCT and p.V959G) in the proband,which originated from her father and mother,respectively.These two mutations were absent in the control,suggesting that these mutations were not SNP.While comparing with the amino acid in NPC1 protein of human,mouse,rat,rabbit,cat and pig,it revealed that p.V959 belonged to a conservative amino acid region and the missense mutation of p.V959G may perturb the function of NPC protein.Neither mutation was found in DNA from amniotic fluid or from the cultivated amniocytes in the second pregnancy,suggesting a normal fetus.c.2284-2287 delCTCT and p.V959G mutation were not found in NPC1 gene analysis of WBC in peripheral blood of the neonate,which was consistent with the prenatal diagnosis.Conclusions PCR-direct sequencing could be used as genetic diagnosis for NPC proband and prenatal diagnosis for its family.The mutation p.V959G may be correlated to late infantile form of NPC.