A novel PTPN11 gene mutation in a patient with LEOPARD Syndrome.

to increased resistance to apoptosis and carcinogenesis. To our knowledge, this mutation has not been previously described. The known mutations of the CYLD gene are mostly located in the C-terminal portion. Germline mutations display tissue-specific function loss. Another possibility would be that the germline mutation determines the tissues where the preferred second hit occurs. When the second hit occurs in eccrineapocrine cells, the patients become susceptible to multiple cylindromas; in hair follicle cells, the patients exhibit susceptibility to multiple cylindromas or MFT. Our study shows the importance of mutation screening of the CYLD gene in patients affected with FC and MFT as well as their relatives to identify early clinical manifestations. Analysis of control volunteers in this report confirms the role of this missense mutation as the cause of this syndrome. Further studies evaluating the effect of this mutation in animal models must be considered.