Focal dermal hypoplasia in a male patient due to mosaicism for a novel PORCN single nucleotide deletion

Background Focal dermal hypoplasia (FDH) is an X-linked dominant disorder caused by nonsense mutations and deletions in the PORCN gene coding for a transmembrane endoplasmic reticulum protein required for Wingless signalling. Symptoms consist mainly of linear atrophic skin defects, skeletal deformities and, in many cases, mental retardation. Osteopathia striata is a nearly constant feature. Approximately 90% of patients are women. A few instances of father-to-daughter transmission and a number of sporadic male cases presumably as a result of somatic mosaicism have been recorded. Objectives The aim of this study was to demonstrate the presence of somatic mosaicism for PORCN mutations in a male patient. Methods We sequenced the PORCN gene in different tissues from a boy with symptoms of FDH. Results We demonstrate post-zygotic mosaicism for a novel deletion in the PORCN gene. Conclusions A novel PORCN deletion, present in a post-zygotic mosaic, causes focal dermal hyplasia in a male patient.