RESUMO
BACKGROUND: Ichthyosis is a disorder of keratinization characterized by diffuse uniform and persistent scales resulting from abnormal epidermal differentiation or metabolism. The identification of steroid sulfatase (STS) as the cause of X-linked ichthyosis (XLI) points to the importance of this enzyme in skin desquamation. Fluorescent in situ hybridization (FISH) analysis is a good diagnostic technique with which to detect a common deletion of the STS gene. OBJECTIVE: In this study, the authors set out to detect the X-linked type of ichthyosis, diagnosed by detection of STS gene deletions among Egyptian males. METHODOLOGY: Egyptian males complaining of X-linked ichthyosis were clinically examined, evaluating pedigree analysis of the family, cytogenetic studies using G-banding technique and FISH using locus specific probe for steroid sulfatase (STS) gene which is located at chromosome Xp22.3. RESULTS: Of patients, 11.11 percent had nocturnal enuresis and 33.33 percent showed STS gene deletion by FISH analysis. CONCLUSION: This study underlines a difficulty in diagnosing X-linked ichthyosis on the clinical features or familial pedigree analysis in Egypt and the importance of cytogenetic and molecular cytogenetic studies for diagnosis. FISH analysis is a good, reliable and rapid diagnostic tool with which to detect STS gene deletion. Since FISH will not detect partial deletion or point mutations, the authors recommend further molecular studies to reach the proper diagnosis of X-linked ichthyosis.