Subject(s)
Alopecia/genetics , Ectodermal Dysplasia/genetics , Hyperpigmentation/genetics , Hypohidrosis/genetics , Keratin-14/genetics , Keratoderma, Palmoplantar/genetics , Nail Diseases/genetics , Phenotype , Skin Neoplasms/genetics , Alleles , Alopecia/diagnosis , Alopecia/pathology , Ectodermal Dysplasia/diagnosis , Ectodermal Dysplasia/pathology , Frameshift Mutation , Humans , Hyperpigmentation/diagnosis , Hyperpigmentation/pathology , Hypohidrosis/diagnosis , Hypohidrosis/pathology , Keratoderma, Palmoplantar/diagnosis , Keratoderma, Palmoplantar/pathology , Nail Diseases/diagnosis , Nail Diseases/pathology , Skin/pathology , Skin Neoplasms/diagnosis , Skin Neoplasms/pathologyABSTRACT
BACKGROUND: Epidermodysplasia verruciformis (EV) is a genodermatosis leading to infections with cutaneous HPV, persistent plane warts and a high rate of non-melanoma skin cancer (NMSC). Biallelic loss-of-function mutations in TMC6 and TMC8 are known to be causative. OBJECTIVE: The aim of this study was to report EV-causing mutations in four patients with EV and to give an overview of all described patients with EV. PATIENTS AND METHODS: We investigated four patients with classical features of EV from two families. All patients were affected by plane warts with typical EV histology since early childhood, and ß-HPVs were detected on their skin. One patient had recurring cutaneous squamous cell carcinomas (cSCC) and carcinomas in situ (Bowen type). We sequenced both TMC6/8 for disease-causing mutations and quantified levels of gene expression. We also performed a systematic literature review to discuss these patients in the context of previously reported cases, mutations already identified, as well as HPV types. RESULTS: Three patients of one family carried a homozygous splice site mutation in TMC8 resulting in aberrantly spliced transcripts that were not degraded. By contrast, no TMC6/8 mutation was detected in the patient from the other family. A systematic literature review revealed 501 described patients with EV. Around 40% of patients with EV analysed for genetic alterations carried no mutation in TMC6/8. While ß-HPVs were identified in the majority of cases, α-HPVs were detected in several individuals. CONCLUSION: The relatively high proportion of EV patients without mutation in TMC6/8 indicates the existence of EV-causing mutations in additional, presently unknown gene(s). However, a homozygous TMC8 splice site mutation in our patients resulted in aberrant transcripts which cannot retain the healthy phenotype. The literature review revealed that HPV-5 is the most commonly identified HPV in patients with EV, but HPV-3, HPV-14 and HPV-20 were unexpectedly identified more frequently than HPV-8.