Objective: To analyze the mutations of COL7A1 gene in two dystrophic epidermolysis bullosa (DEB) pedigrees and make prenatal diagnosis for high-risk 11-week-old fetuses.
Methods: COL7A1 gene was first analyzed by next-generation sequencing for detecting suspicious gene mutations of two probands. And then the mutations were confirmed by polymerase chain reaction and Sanger sequencing in probands, parents and unrelated healthy individuals. Prenatal genetic diagnosis for high-risk fetus was performed by chorionic villus sampling after genotyping.
Results: Four mutations were detected in 2 pedigrees: c.5230G>T (p.E1744X), c.5932C>T (p.R1978X), c.5605-10 T>G (IVS66-10 T>G) , c.8305-1G>A (IVS110-1G>A) among which p.E1744X, IVS66-10 T>G and IVS110-1G>A mutations were first reported. The proband in No.1 family carried p.E1744X and p.R1978X nonsense mutations and her parents were carriers. The proband in No.2 family carried IVS66-10 T>G and IVS110-1G>A splicing mutations and her parents were carriers. All four mutations were not found in 100 healthy individuals. Prenatal diagnosis in No.1 family indicated that the fetus also carried p.E1744X and p.R1978X nonsense mutations as the proband. The fetal parents decided to terminate pregnancy and the result of gene analysis for aborted tissue was consistent with that of prenatal diagnosis.
Conclusions: COL7A1 gene mutation is etiological for two DEB families. Next-generation sequencing plus Sanger sequencing is effective and accurate for making gene diagnosis and prenatal diagnosis.