Detection of steroid sulfatase gene deletion (STS) in Egyptian males with X-linked ichthyosis

Introduction: Ichthyosis is a disorder of keratinization characterized by diffuse uniform and persistent scales resulting from abnormal epidermal differentiation or metabolism. Ichthyosiform dermatoses are classified into four major types, ichthyosis vulgaris, X-Linked ichthyosis, congenital recessive ichthyosis and lastly epidermolytic hypekeratosis which was previously called bullous ichthyosiform erythroderma. The identification of steroid sulfatase as the cause of X-Linked ichthyosis points to the importance of this enzyme in skin desquamation. Fluorescent in situ hybridization (FISH) analysis is a good diagnostic technique to detect a common deletion of the STS gene. Most patients with X-Linked ichthyosis have large deletions of the STS locus. Aim of the work: In this study, we aimed to detect the X-Linked type of ichthyosis, diagnosed by detection of STS gene deletions among Egyptian males. Patients and Methods: We performed this study on Egyptian males complaining of X-linked ichthyosis who were subjected to clinical examination, pedigree analysis of the family, cytogenetic studies using G-banding technique and fluorescent in situ hybridization (FISH) using locus specific probe for stereoid sulfatase (STS) gene which is located at chromosome Xp22.3. Our results showed that 11.11% of patients had nocturnal enuresis and 33.33% showed STS gene deletion by FISH study. Conclusion: The current study underlines the difficulty of diagnosis of X-Linked ichthyosis on the clinical features or pedigree analysis of the family in Egypt and the importance of cytogenetic and molecular cytogenetic studies for diagnosis. Fluorescent in situ hybridization (FISH) technique is a good, reliable, and rapid diagnostic tool to detect STS gene deletion. Since FISH will not detect partial deletion or point mutations, we recommended further molecular studies to reach the proper diagnosis of X-linked ichthyosis. Keywords: Ichthyosis- X-Linked, gene deletion, fluorescence in situ hybridizationyword Egypt. J. Hum. Genet Vol. 8 (2) 2007: pp. 209-21