{'fraction_non_alphanumeric': 0.03536977491961415, 'fraction_numerical': 0.02067064768029398, 'mean_word_length': 5.424778761061947, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 2, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Novel substitution and frameshift mutations of CYLD in two Chinese families with multiple familial trichoepithelioma

SIR, Multiple familial trichoepithelioma (MFT; MIM 601606), a rare autosomal dominant inherited disorder, is characterized by the development of numerous, firm skin-coloured papules that originate from hair follicles. The papules most commonly occur between the first and second decade of life, predominantly on the face, nose, forehead and upper lip. Although these lesions are neither life-threatening nor debilitating, the effects of multiple trichoepitheliomas can be cosmetically and psychologically devastating resulting in a low self-esteem and poor body image. In 2004, we successfully mapped the recessive oncogene CYLD (cylindromatosis) on chromosome 16q12–q13. A mutation of this gene forms the genetic basis of MFT. Nine germline mutations among different races have been described for the CYLD gene, cosegregating with the MFT phenotype. However, no phenotype–genotype correlation has been observed. In this study we identified a novel substitution (c.2409C>G) and frameshift (c.1364_1365delAA) CYLD mutation in two families with MFT, and a genetic diagnosis was made for the son of one of the probands based on the presence of the c.2409C>G mutation before onset of any clinical manifestations. Two unrelated families with isolated autosomal dominant MFT were identified in Jiangxi and Anhui province in China (Fig. 1a,b). After obtaining informed consent, all family members were examined by experienced dermatologists. Four affected individuals were diagnosed based on clinical features in family 1, and all patients presented with a relatively mild phenotype similar to lesions observed in the proband (Fig. 1c). The proband (II:2) of family 2 was a 63-year-old woman, with numerous dome-shaped, skin-coloured, firm nodules ranging from 5–10 mm in size (Fig. 1d). Her younger brother (II:5) exhibited more severe lesions. Histological analysis of the tumours revealed the typical histological characteristics of trichoepithelioma (dermal aggregates of basaloid cells with connection to or differentiation towards hair follicles) (Fig. 1e, f).