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Summary Introduction 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. Materials and methods 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. Results 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. Conclusion 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.

Incontinentia Pigmenti (IP) is an X-linked rare genodermatosis caused by mutations in the IKBKG gene, which is essential to NF-κB pathway activation and thus fundamental for cell survival. Our objective was to study the intrafamilial clinical variability in IP by investigating how the signs of IP, and especially dental anomalies, vary within affected families. Four families, encompassing a total of 15 IP familial cases, were included in the study. The patients were subjected to clinical examination and collection of family histories for assessment of intrafamilial clinical variability. All familial cases carried the IKBKGdel recurrent deletion. A noticeable intrafamilial clinical variability was observed in all studied families, with mild and severe cases co-occurring within a same family. Additionally, to best of our knowledge, our study was the first to address the variability of dental defects within IP families, and here too, our results reveal remarkable differences among affected relatives. A number of as yet unidentified genes might act as modifiers, influencing disease expressivity. Our study found important clinical variability within four IP families and contributes to the understanding of the genetic background involved in IP expressivity.

Incontinentia pigmenti is a rare neuroectodermal dysplasia caused by a defect in the IKBKG gene (formerly known as NEMO). There are 27.6 new cases per year worldwide; 65% to 75% are sporadic mutations, and 25% to 35% are familial. It is usually lethal in males, but females survive because of X-inactivation mosaicism. The disorder is typically identified by unique skin findings, a series of four stages that emerge throughout the first year of life. The central nervous system manifestations in the eye and in the brain cause the most disability. Defects of hair, nails, and teeth occur, and there can be other systemic involvement. Surveillance protocols for medical management have been established by the Incontinentia Pigmenti International Foundation. This article will summarize the existing knowledge of this condition and detail the protocols to help manage the care of the infant or child who presents with incontinentia pigmenti.

In this issue of Blood, Miot et al report encouraging results in a retrospective analysis of hematopoietic stem cell transplantation (HSCT) in 29 patients with hypomorphic mutations in the IKBKG gene encoding nuclear factor κB essential modulator (NEMO).

International audience; BACKGROUND:Noonan syndrome (NS) is an autosomal dominant multisystem disorder caused by the dysregulation of several genes belonging to the RAS Mitogen Activated Protein Kinase (MAPK) signaling pathway. Incontinentia Pigmenti (IP) is an X-linked, dominantly inherited multisystem disorder.CASE PRESENTATION:This study is the first report of the coexistence of Noonan (NS) and Incontinentia Pigmenti (IP) syndromes in the same patient. We report on the clinical phenotype and molecular characterization of this patient. The patient was examined by a pluridisciplinary staff of clinicians and geneticist. The clinical diagnosis of NS and IP was confirmed by molecular investigations. The newborn girl came to our clinics due to flagrant dysmorphia and dermatological manifestations. The clinical observations led to characterize the Incontinentia Pigmenti traits and a suspicion of a Noonan syndrome association. Molecular diagnosis was performed by Haloplex resequencing of 29 genes associated with RASopathies and confirmed the NS diagnosis. The common recurrent intragenic deletion mutation in IKBKG gene causing the IP was detected with an improved PCR protocol.CONCLUSION:This is the first report in the literature of comorbidity of NS and IP, two rare multisystem syndromes.

Ectodermal dysplasias (ED) are uncommon genetic disorders resulting in abnormalities in ectodermally derived structures. Many ED-associated genes have been described, of which ectodysplasin-A (EDA) is one of the more common. The NF-κB essential modulator (NEMO encoded by the IKBKG gene) is unique in that mutations result in severe humoral and cellular immunologic defects in addition to ED. We describe three unrelated kindreds with defects in both EDA and IKBKG resulting from X-chromosome crossover. This demonstrates the importance of thorough immunologic consideration of patients with ED even when an EDA etiology is confirmed, and raises the possibility of a specific phenotype arising from coincident mutations in EDA and IKBKG.

The objective of this study was to present a systematic review of the central nervous system (CNS) types of anomalies and to consider the possibility to include CNS anomalies in Incontinentia pigmenti (IP) criteria. The analyzed literature data from 1,393 IP cases were from the period 1993–2012. CNS anomalies were diagnosed for 30.44% of the investigated IP patients. The total number of CNS types of anomalies per patient was 1.62. In the present study there was no significantly higher number of anomalies per patient in females than males. The most frequent CNS types of anomalies were seizures, motor impairment, mental retardation, and microcephaly. The most frequently registered CNS lesions found using brain imaging methods were brain infarcts or necrosis, brain atrophies, and corpus callosum lesions. IKBKG exon 4–10 deletion was present in 86.00% of genetically confirmed IP patients. The frequency of CNS anomalies, similar to the frequency of retinal anomalies in IP patients, concurrent with their severity, supports their recognition in the list of IP minor criteria.