Mutation analysis of the COL7A1 gene in 4 cases of recessive dystrophic epidermolysis bullosa / 中华皮肤科杂志

Objective:To analyze gene mutations in and clinical phenotypes of 4 children with recessive dystrophic epidermolysis bullosa (RDEB) .Methods:Clinical data were collected from 4 children with RDEB, and DNA was extracted from peripheral blood samples of the children and their parents. A multi-gene panel targeting congenital epidermolysis bullosa was used for high-throughput sequencing. After identification of causative gene mutations, Sanger sequencing was performed to bidirectionally verify the mutations in the patients and their parents.Results:Genetic testing showed 8 compound heterozygous mutations in the COL7A1 gene in the 4 cases. Case 1 was diagnosed with moderate generalized RDEB, and inherited a paternal mutation c.7828C>T and a maternal mutation c.448G> A; case 2 was also diagnosed with moderate generalized RDEB, and inherited a paternal mutation c.3625_3635del and a maternal mutation c.2726_2728del; case 3 was diagnosed with localized RDEB, carrying a paternal mutation c.682+1G>A and an allelic mutation c.5532+1G>A, but the mutation c.5532+1G>A was not identified in the DNA extracted from the parental peripheral blood samples; case 4 was diagnosed with severe generalized RDEB, and inherited a paternal mutation c.5196delC and a maternal mutation c.500_501insAGGG. Among these mutations, c.2726_2728del and c.5196delC had not been reported previously.Conclusions:All the 4 children with RDEB carried compound heterozygous mutations in the COL7A1 gene, which may be the cause of RDEB. The phenotypes of biallelic frameshift mutation carriers appearred more severe than those of carriers of compound heterozygous mutations composed of biallelic splice site, missense and nonsense, frameshift and amino acid deletion or insertion mutations.

Gene mutation analysis of congenital skin defects: a case report / 中华皮肤科杂志

A female infant presented with skin defects and blisters for 2 hours after birth.Physical examination showed asymmetric skin defects on both lower extremities and left wrist,a thin-walled blister on the dorsal side of the right hand,and partial loss of the oral mucosa.No other abnormal signs were found.Genetic testing showed a heterozygous pathogenic mutation c.481C ＞ T (p.Gln161*) in exon 4 of the COL7A1 (NM-000094) gene and a heterozygous pathogenic mutation c.1837C ＞ T (p.Arg613*) in exon 14 of the COL7A1 (NM-000094) gene,which were also identified in the patient's father and mother respectively.The infant was diagnosed with congenital skin defects.The patient received protective isolation,focal washing with 0.9％ sodium chloride physiological solution,topical epidermal growth factor and comprehensive treatment for infection prevention.After 6-day treatment,the patient was discharged with dry and non-exudative skin lesions.This case prompted that abnormal heterozygosis mutation at C.481 and C.1837 sites on the COL7A1 (NM-000094) gene could form compound heterozygote,acting as pathogenic mutation.

Mutation analysis of the COL7A1 gene in pretibial dominant dystrophic epidermolysis bullosa / 中华皮肤科杂志

Objective To explore the role of type Ⅶ collagen (COL7A1) gene in the pathogenesis of pretibial dominant dystrophic epidermolysis bullosa (DDEB-Pt).Methods Peripheral blood samples were obtained from a sporadic Chinese patient of Han nationality with DDEB-Pt,his parents and 100 healthy human controls.A modified salting-out method was used to extract genomic DNA from the blood samples,and PCR was performed to amplify 118 exons of the COL7A1 gene followed by DNA sequencing.Results A G→A mutation was identified at position 6109 (G6109A) in exon 78 of the COL7A1 gene in this patient,which caused a change from GCT to ACT at codon 2037 in the triple helix region,and resulted in the substitution of glycine (Gly) by arginine (Arg) (p.Gly2037Arg).Conclusion A novel glycine substitution mutation was identified in the COL7A1 gene in the patient with DDEB-Pt,which may be a pathogenic mutation.

Application of next generation sequencing technology for genetic diagnosis of a neonate and the family with heredi-tary dystrophic epidermolysis bullosa / 临床儿科杂志

Objectives To detect genetic causes of dystrophic epidermolysis bullosa (DEB). Methods Next-generation sequencing was used to detect a neonate with DEB. Sanger sequencing was used to confirm the results and detect his parents and grandmother on his mother side from the family. Results The neonate was found to have heterozygous mutation c.6781C>T of exon 86 in COL7A1 gene.This mutation results in R2261X nonsense mutation in typeⅦcollagen. His mother and grand-mother on his mother side have the same mutation. Conclusion Next-generation sequencing technology is a useful tool for the detection of mutations of COL7A1 gene, which is valuable for clinical application.

Mutations of COL7A1 gene in three cases of dystrophic epidermolysis bullosa pruriginosa / 中华皮肤科杂志

Objective To detect the mutations of COL7A1 gene in three cases of dystrophic epidermolysis bullosa pruriginosa (DEBP). Methods Clinical data were collected from 3 patients with DEBP. Skin lesions were obtained from these patients and subjected to transmission electron microscopy. DNA was extracted from the peripheral blood of the 3 patients, their 16 relatives, and 150 unrelated normal human controls, and PCR was performed to amplify all the exons and flanking sequences of COL7A1 gene followed by sequencing.Results The patient 1 and 2 had family history, whereas the case 3 was sporadic. Transmission electron microscopy showed tissue cleavage beneath lamina densa in case 1 and slightly decreased anchoring fibrils in some areas of the lesions in case 1 and 3. Three heterozygous mutations of COL7A1 gene, i.e., c. G6734T, c.G6859A and c. G5318T, which leaded to three amino acid mutations, i.e., p. G2245V, p. G1773V and p. G2287R, were found in patient 1, 2 and 3 respectively. Of them, p. G2245V and p. G1773V were novel mutations. The mutations strictly cosegregated with the phenotype in the patients of family 1 and 2. No mutation was detected in the unaffected parents of patient 3 or the 150 unrelated healthy controls. Conclusions The p. G2245V, p. G2287Rand p. G1773V mutations of COL7A1 gene may be responsible for the phenotype of DEBP in the three cases,and of them, p. G2245V and p. G1773V have never been reported.