Gene Diagnosis And Prenatal Diagnosis For A Large Pedigree With Choroideremia Combined The Non-invasive Prenatal Testing (NIPT) And The Next-generation Sequencing (NGS)

Objective: To establish a new non-invasive prenatal diagnosis technology for gene identification and prenatal diagnosis for choroideremia disease by combined the next-generation sequencing(NGS)and non-invasive prenatal diagnosis(NIPD)technology.Methods:(1)After informed consent,a large pedigree with an X-linked recessive disease for choroideremia was collected and identified the disease-causing gene by NGS.(2)Cell-free DNA(cff DNA)was extracted from maternal plasma and nested PCR amplification and real-time quantity PCR for SRY gene were performed by NIPD.The Sanger ksequencing was used for verified with fetus amniotic fluid DNA.Results:(1)A nonsense mutation(c.C799T:p.R267X)of the CHM gene located on X chromosome was detected in the proband(Ⅳ: 7)and the same mutation was identified in the other 5 males with choroideremia,in the meantime,3female carriers with no symptoms carrying heterozygous mutation were also identified.(2)The daughter of the proband(Ⅴ :11)wanted to have a prenatal diagnosis when she was pregnant with three months.The detection of SRY was negative,indicating that the fetus may be a female.And the heterozygous mutation,same with her mother,was verified by sequencing of the amniotic fluid DNA.The baby does not show any symptoms at all after birth with one and a half years following up.Conclusions: The combination of a NGS and NIPD,as a high accuracy method,is successfully applied to the diagnosis of a large pedigree with choroideremia.The establishment of this method will provide not only a valuable strategy for the precision diagnosis of various retinal diseases,but also the possibility for genetic counseling and clinical treatment.