A CLINICAL AND GENETIC-STUDY OF X-LINKED RECESSIVE ICHTHYOSIS AND CONTIGUOUS GENE DEFECTS

X-linked recessive ichthyosis (XLI) is caused by a deletion, or mutati on, of the steroid sulphatase gene on the distal short arm of the X ch romosome (Xp22.3). This region of the X chromosome is particularly sus ceptible to deletions. Such deletions can occasionally extend to invol ve neighbouring genes, causing a contiguous gene defect. Therefore, XL I may be associated with Kallmann's syndrome (KS), mental retardation, X-linked recessive chondrodysplasia punctata and short stature. We ha ve reviewed 33 patients with XLI. Nine showed evidence of contiguous g ene defects. A further four had neurological deficit sustained at the time of birth. This study highlights the importance of screening patie nts with X-linked recessive ichthyosis for neighbouring genetic disord ers and, in particular, the early identification of KS, as delay in di agnosis may lead to infertility and osteoporosis. Parents should be wa rned about possible obstetric complications due to prolonged labour in future pregnancies.