Detection of steroid sulfatase gene deletion [STS] in Egyptian males with X-linked ichthyosis

ABSTRACT

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 in this study, we aimed to detect the X-Linked type of ichthyosis, diagnosed by detection of STS gene deletions among Egyptian males. 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. 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