Abstract: Xu Zhe, Lin Zhimiao Department of Dermatology, Beijing Children′s Hospital, Capital Medical University, National Center for Children′s Health, Beijing 100045, China （Xu Z）; Department of Dermatology, Peking University First Hospital, Beijing 100034, China （Lin ZM） Corresponding author: Xu Zhe, Email: zhexu_cmu@163.com 【Abstract】 Objective To detect mutations of the COL7A1 gene in 2 families with recessive dystrophic epidermolysis bullosa（RDEB）, and to perform prenatal diagnosis during the pregnancy of patients′ mothers. Methods Clinical data were collected from 2 patients with RDEB. DNA was extracted from the peripheral blood samples from the patients, their parents and 100 unrelated healthy people who served as controls. PCR was performed to amplify all the 118 exons of the COL7A1 gene followed by DNA sequencing. After identification of pathogenic mutations, amniotic fluid cells were obtained by amniocentesis during the next pregnancy of the patients′ mothers, and genomic DNA was extracted from uncultured or cultured amniotic fluid cells followed by amplification and DNA sequencing to detect mutations in the COL7A1 gene. The results were compared with patients′ results for prenatal diagnosis. After delivery, venous blood samples were collected from the neonates to detect mutations in the COL7A1 gene. All the results were verified by bidirectional sequencing. Results Compound heterozygous mutations in the COL7A1 gene were identified in the 2 patients. Two heterozygous mutations （c.5453G > A and c.6781C > T） in the COL7A1 gene were found in case 1, which resulted in the p.G1818D mutation and the formation of a premature termination codon p.R2261Efs*25. Additionally, the c.5453G > A and c.6781C > T mutations were inherited from his father and mother respectively. Another 2 heterozygous mutations （c.6205C > T and c.8272_8272delG） in the COL7A1 gene were identified in case 2, which led to the p.R2069C and p.V2758Sfs*28 mutations in encoded proteins, and the c.6205C > T and c.8272_8272delG mutations were inherited from the patient′s father and mother respectively. None of the above mutations in the COL7A1 gene was found in the uncultured or cultured amniotic fluid cells, which were collected from the 2 patients′ mothers during the next pregnancy. After birth, the neonates showed normal skin and mucosa without blisters, and genetic testing showed none of the above mutations in the COL7A1 gene in the neonates. Conclusion Compound heterozygous mutations in the COL7A1 gene were found in the 2 patients with RDEB, and prenatal diagnosis was successfully performed in the 2 patients′ mothers during the next pregnancy.