Evidence of the high prevalence of neurological disorders in nonsyndromic X-linked recessive ichthyosis: a retrospective case series

[Background]: X-linked recessive ichthyosis (XLI) is a relatively common type of ichthyosis caused by a deficiency in the steroid sulfatase (STS) enzyme. It is the only type of ichthyosis that can be both syndromic and nonsyndromic. Typical clinical features include dark-brown scale of variable size favouring the extensor surfaces of the extremities.[Objectives]: To characterize clinically nonsyndromic XLI, with a particular focus on extracutaneous manifestations.[Methods]: This was a multicentre retrospective review of clinical findings from a case series of patients with a clinical and genetic diagnosis of XLI.[Results]: We identified 30 patients with XLI belonging to 25 different families carrying a deletion in the STS locus. All patients had dark scales of variable size on the extensor surfaces of the extremities. Lack of flexural involvement and pruritus were common but inconsistent findings, whereas palmoplantar hyperlinearity was absent in all but one patient. A history of orchiopexy was present in 10% and thus was more common than expected vs. the general population (3%). Neurological disorders including epilepsy (13%) and attention deficit hyperactivity disorder (ADHD; 30%) were over-represented in patients with XLI.[Conclusions]: This was a retrospective study with a limited number of patients. In the absence of confirmatory genetic testing and family history of the disease, dark-brown scale of the extensor surfaces and the absence of palmoplantar hyperlinearity appear to be the most reliable clinical findings supporting a diagnosis of XLI. Dermatologists should be aware of the high prevalence of ADHD and epilepsy in patients with nonsyndromic XLI

Hypotrichosis simplex of the scalp and peeling skin disease, two sides of the same coin

Corneodesmosin (CDSN) is a keratinocyte adhesion glycoprotein located in the extracellular domain of corneodesmosomes and in the inner root sheath of the hair follicles.1 Both mono-allelic and bi-allelic pathogenic variants in the CDSN gene have been shown to produce distinctive dermatological conditions. Here, we present two paediatric cases illustrating the wide clinical spectrum of CDSN anomalies