A novel mutation of CYLD in a Chinese family with multiple familial trichoepithelioma and no CYLD protein expression in the tumour tissue

Conflicts of interest: none declared. Sir, Multiple familial trichoepithelioma (MFT; OMIM 601606) is an autosomal dominant skin disorder. The gene CYLD mapped to locus 16q12–q13 has been shown to be responsible for MFT.1 To date, eight germline mutations have been described in the CYLD gene among eight families who have MFT.1–5 MFT is considered to be a syndrome in which tumours develop from undifferentiated germ cells of the folliculosebaceous–apocrine unit.6 Familial cylindromatosis (FC) and MFT were originally described as phenotypic variations caused by mutations of the same gene.7 Massoumi et al.8 reported that the CYLD protein is dramatically downregulated in the tissue of FC, but is prominently expressed in the inner root sheath of hair follicles from normal human scalp. However, the role that CYLD plays in the growth and development of an MFT tumour has yet to be elucidated. A family of three generations with MFT that includes five affected and 15 unaffected individuals was identified at the Dermatology Clinic at Peking Union Medical College (PUMC) Hospital in January 2005. The patient is a 24‐year‐old female who resides in Beijing. When she was 5 years old, she began to develop on her face numerous firm, skin‐coloured, dome‐shaped papules and nodules, 0·2–0·5 cm in diameter. Other affected individuals among her relatives have similar skin lesions, which characteristically slowly increased both in number and size until the individuals were about 30 years of age. Skin biopsies were taken from the facial lesions of the proband’s father for histopathological examination. Clinical and histological features confirmed the diagnosis of MFT. After obtaining informed consent and notifying patients of their right to confidentiality and the voluntary nature of the study, we collected blood specimens from four patients and from three normal members of the family.