Incontinentia pigmenti in boys: Causes and consequences

Abstract

Incontinentia pigmenti (IP) is an X-linked genodermatosis caused by mutation of the NEMO/IKBKG gene. While lethal in male foetuses, heterozygous females survive because of X-inactivation mosaicism. Herein we discuss 9 male patients with IP. This is an observational, descriptive, retrospective, multicentre, French study carried out with the help of the SFDP research group. Statistical analysis was performed both on our own patients and on those reported in the literature. Nine boys with no family history of IP but with typical neonatal skin reactions were included. Genetic analysis of blood (n=8) and skin biopsy (n=3) confirmed the diagnosis of IP by identification of common deletion of the IKBKG/NEMO gene (exons 4 to 10) in the state of somatic mosaic in 6 and 2 cases respectively. Where analysed, the karyotype was normal (n=6). Over a median follow-up period of 48 months (3 months to 10 years), 3 patients had neurological abnormalities, 2 had severe ophthalmologic abnormalities, and 1 had dental abnormalities. Extensive skin involvement is a systemic risk factor, unlike cutaneous scarring. IP in boys is often due to a mosaic mutation that should be sought in blood and skin. Long-term neurological and ophthalmological monitoring is essential, especially in cases of extensive skin involvement.