Multiple familial trichoepithelioma (MFT) and familial cylindromatosis are two 
clinically distinct cancer syndromes. MFT patients developed mostly 
trichoepithelioma in the face while cylindromatosis patients developed 
cylindromas predominantly (approximately 90%) on the head and neck. However, 
multiple familial trichoepithelioma is occasionally associated with familial 
cylindromatosis while cylindromatosis patients can also develop 
trichoepithelioma. This has led to the speculation that the 2 types of 
dermatoses may be caused by dysfunction of a common pathway. Previously, a 
candidate MTF locus has been mapped to 9p21 while disease gene for familial 
cylindromatosis, the CYLD gene located on 16q21-13 has been identified. Here, we 
show that mutations in the CYLD gene are also the genetic basis for three 
different Chinese families with MFT. Sequence analysis reveal a single 
nucleotide deletion, c.1462delA (P.Ile488fsX9) in exon 9, a nonsense mutation, 
c.2128C>T (p. Gln710X) in exon 17, and a missense mutation, c.2822A>T (p. 
Asp941Val) in exon 21 in each of the three families respectively. This provides 
direct evidence that the mutations in CYLD can cause two clinically distinct 
cancer syndromes.