A novel missense mutation in theCOL7A1gene causes epidermolysis bullosa pruriginosa

Clinical subtypes and molecular basis of epidermolysis bullosa in Kuwait

BACKGROUND

Epidermolysis bullosa (EB) is a clinically and genetically heterogeneous blistering skin disease, but in countries such as Kuwait, there are very limited data on the clinical and molecular pathology of EB. To improve understanding of EB in Kuwait, we report the experience of a local tertiary referral center over a 17.5 year period (January 2000-June 2017) in establishing clinical and molecular diagnoses.

METHODS

Review of hospital records and diagnostic reports. Individual cases were diagnosed by combinations of clinical assessment, skin biopsy (immunohistochemistry and transmission electron microscopy), Sanger sequencing of EB genes, and whole exome sequencing.

RESULTS

Fifty-four families with EB were registered with the clinic over this period, 41 of whom (84 patients) participated in diagnostic studies. Thirty-seven of these 41 families had consanguineous marriages; 34 had recessive forms of EB, while only seven had dominant subtypes. Recurrent mutations were observed in epidermal dystonin, transglutaminase 5, and type VII collagen.

CONCLUSIONS

The prevalence of EB in Kuwait is approximately three times that of internationally cited rates with an over-representation of autosomal recessive variants. Establishing the molecular basis of EB in Kuwait with accurate diagnostic subtyping provides a basis for determining healthcare requirements and improving patient management of EB.

Epidermolysis bullosa pruriginosa: a systematic review exploring genotype-phenotype correlation

INTRODUCTION

Epidermolysis bullosa pruriginosa (EBP) is a clinical variant of dystrophic epidermolysis bullosa (DEB), characterized by intense pruritus and hypertrophic, lichenified, prurigo-like papules, plaques, and nodules secondary to scratching. These clinical findings have been attributed to various mutations in the COL7A1 gene. Previous reports have yielded inconsistent findings regarding a possible genotype-phenotype relationship in EBP.

OBJECTIVE

Our aim was to conduct a systematic review aimed at assessing the genotype-phenotype correlation in EBP.

METHODS

A systematic review was conducted using PubMed, Medline, EMBASE, and Cochrane databases for all reports of mutation-verified EBP, published from 1946 to September 2014. Statistical comparison of clinical findings between mutation types was performed using logistic regression analysis.

RESULTS

The review included a total of 28 articles with 74 individuals, which consisted of level 4 non-controlled case series (grade C) and level 5 case reports (grade D). Previous reported mutation types included glycine substitution (GS, 52.7%), in-frame skipping (IFS, 33.8%), non-glycine substitution (NGS, 8.1%), and premature termination codon (PTC, 5.4%). The most common clinical findings were extremities involvement, linear configuration, and nail dystrophy. In comparison with GS mutation carriers, IFS carriers had a higher likelihood of (1) being male (OR 2.99; p = 0.043; 95% CI 1.27-11.4) and (2) presenting with blisters (OR 4.10; p = 0.013; 95% CI 1.34-12.5).

CONCLUSIONS

To our knowledge, this study is the first systematic review examining the relationship between mutation type and clinical presentation in EBP. The findings in this review (1) identify common clinical characteristics of EBP that may help in the assessment of patients with possible EBP; and (2) indicate that certain mutation carriers may have a higher likelihood of exhibiting particular phenotypes. In the case of potential diagnostic challenge, assessment for presence of common clinical findings as well as molecular testing may facilitate correct identification and prognostication.

A novel COL7A1 gene mutation causing pretibial epidermolysis bullosa: report of a Chinese family with intra-familial phenotypical diversity

Pretibial epidermolysis bullosa (PEB) is an extremely rare subtype of dominant dystrophic epidermolysis bullosa (DDEB) caused by mutation of the COL7A1 gene. More than 730 mutations have been identified in patients with DDEB, but only five mutations have been found to be related to PEB. In this study, a novel heterozygous nucleotide G>T transition at position 6101 in exon 73 of COL7A1 was detected, which resulted in a glycine to valine substitution (G2034V) in the triple-helical domain of type-VII collagen. This is the first report to show that one mutation caused a broad range of severity of disease in one family with PEB. These data suggest that c.6101G>T may influence the phenotype of PEB. They also contribute to the expanding database on COL7A1 mutations.

Epidermolysis bullosa pruriginosa: further clarification of the phenotype

A defect in type VII collagen causes dystrophic epidermolysis bullosa (DEB). The pruriginosa variant (DEB-Pr) is unique because its initial presentation may be delayed until adolescence or adulthood, and its predominant feature is scarring and pruritus without the characteristic skin fragility of DEB. We describe three families with multiple affected members in which DEB-Pr shows an autosomal-dominant inheritance pattern. All affected individuals were examined, and three previously unreported COL7A1 mutations were identified.

An incompletely penetrant novel mutation in COL7A1 causes epidermolysis bullosa pruriginosa and dominant dystrophic epidermolysis bullosa phenotypes in an extended kindred

Epidermolysis bullosa pruriginosa (EBP) is a rare subtype of dystrophic epidermolysis bullosa (DEB) characterized by intense pruritus, nodular or lichenoid lesions, and violaceous linear scarring, most prominently on the extensor extremities. Remarkably, identical mutations in COL7A1, which encodes an anchoring fibril protein present at the dermal-epidermal junction, can cause both DEB and EBP with either autosomal dominant or recessive inheritance. We present one family with both dystrophic and pruriginosa phenotypes of epidermolysis bullosa. The proband is a 19-year-old Caucasian woman who initially presented in childhood with lichenoid papules affecting her extensor limbs and intense pruritus consistent with EBP. Her maternal grandmother saw a dermatologist for similar skin lesions that developed without any known triggers at age 47 and mostly resolved spontaneously after approximately 10 years. The proband's younger brother developed a small crop of pruritic papules on his elbows, dorsal hands, knees, and ankles at age 13. Her second cousin once removed, however, reported a mild blistering disease without pruritus consistent with DEB. Genetic sequencing of the kindred revealed a single dominant novel intron 47 splice site donor G>A mutation, c.4668 + 1 G>A, which we predict leads to exon skipping. Incomplete penetrance is confirmed in her clinically unaffected mother, who carries the same dominant mutation. The wide diversity of clinical phenotypes with one underlying genotype demonstrates that COL7A1 mutations are incompletely penetrant and strongly suggests that other genetic and environmental factors influence clinical presentation.