Unraveling incontinentia pigmenti: A comparison of phenotype and genotype variants

Incontinentia pigmenti

Incontinentia pigmenti (IP) is a rare X-linked dominant, multi-system genetic disorder characterized by evolving skin lesions that occurs almost exclusively in females. Additional manifestations most often involve embryologically-derived ectodermal tissues including the central nervous system (CNS), eyes, hair, teeth and nails. IP is associated with a wide range of neurologic abnormalities, several of which can be associated with significant morbidity. In the neonatal period, while the pathophysiology is poorly understood, inflammatory microvascular changes can lead to ischemic strokes in non-vascular territories and acute disseminated encephalomyelitis, resulting in serious chronic neurologic sequelae such as epilepsy, cerebral palsy and intellectual disability. Additional neuroimaging findings may include periventricular and subcortical white matter abnormalities and cerebral as well as cerebellar dysgenesis. Advancements over time have allowed for improved phenotyping, identification of the causative IKBKG pathogenic variant, creation and refinement of clinical diagnostic criteria and the development of management guidelines which promote multi-disciplinary care. Due to frequent CNS involvement, neurologists play a critical role in the treatment of individuals with IP throughout the lifespan.

Case report: Variability in clinical manifestations within a family with incontinentia pigmenti

Diagnosing skin diseases in children can be a complex interdisciplinary problem. Incontinentia pigmenti (IP), also known as Bloch-Sulzberger syndrome, is a rare hereditary genodermatosis related to a mutation in the IKBKG gene. We present a family case of IP described from the perspective of various specialists, including dermatologists, oncologists, geneticists, dentists, and trichologists. The peculiarity of this case is the development of squamous cell carcinoma (SCC) on the shin of a 10-year-old female patient with IP. The patient had a positive family history: her mother and two sisters also displayed clinical manifestations of IP with involvement of skin, teeth and hair. The presence of exons 4-10 deletion in the IKBKG gene in all affected females was confirmed by detailed genetic evaluation using long-range PCR, and also high degree of X-chromosome inactivation skewing was demonstrated. The family underwent a comprehensive examination and was followed up for 2 years with successful symptomatic treatment of dermatologic manifestations. Recommendations were also made regarding dental and hair problems. By the end of the follow-up period, patients had stabilized, with the exception of a 36-year-old mother who developed generalized morphea. The study demonstrates the varying expressiveness of clinical symptoms among family members and emphasizes the importance of timely diagnosis for effective management of patients with IP.

Whorled Scarring Alopecia: A Rare Cutaneous Finding in Incontinentia Pigmenti or Overlooked Phenomenon? A Case Report of Incontinentia Pigmenti with Trichoscopic and Dermoscopic Findings

Abstract is missing (Short Communication)

An efficient molecular genetic testing strategy for incontinentia pigmenti based on single-tube long fragment read sequencing

Incontinentia pigmenti (IP) is a rare X-linked dominant neuroectodermal dysplasia that primarily affects females. The only known causative gene is IKBKG, and the most common genetic cause is the recurrent IKBKG△4-10 deletion resulting from recombination between two MER67B repeats. Detection of variants in IKBKG is challenging due to the presence of a highly homologous non-pathogenic pseudogene IKBKGP1. In this study, we successfully identified four pathogenic variants in four IP patients using a strategy based on single-tube long fragment read (stLFR) sequencing with a specialized analysis pipeline. Three frameshift variants (c.519-3_519dupCAGG, c.1167dupC, and c.700dupT) were identified and subsequently validated by Sanger sequencing. Notably, c.519-3_519dupCAGG was found in both IKBKG and IKBKGP1, whereas the other two variants were only detected in the functional gene. The IKBKG△4-10 deletion was identified and confirmed in one patient. These results demonstrate that the proposed strategy can identify potential pathogenic variants and distinguish whether they are derived from IKBKG or its pseudogene. Thus, this strategy can be an efficient genetic testing method for IKBKG. By providing a comprehensive understanding of the whole genome, it may also enable the exploration of other genes potentially associated with IP. Furthermore, the strategy may also provide insights into other diseases with detection challenges due to pseudogenes.

Uncovering incontinentia pigmenti: From DNA sequence to pathophysiology

Incontinentia pigmenti (IP) is an X-linked dominant genodermatosis. The disease is known to be caused by recurrent deletion of exons 4-10 of the Inhibitor Of Nuclear Factor Kappa B Kinase Regulatory Subunit Gamma (IKBKG) gene located at the Xq28 chromosomal region, which encodes for NEMO/IKKgamma, a regulatory protein involved in the nuclear factor kappa B (NF-κB) signaling pathway. NF-κB plays a prominent role in the modulation of cellular proliferation, apoptosis, and inflammation. IKBKG mutation that results in a loss-of-function or dysregulated NF-κB pathway contributes to the pathophysiology of IP. Aside from typical skin characteristics such as blistering rash and wart-like skin growth presented in IP patients, other clinical manifestations like central nervous system (CNS) and ocular anomalies have also been detected. To date, the clinical genotype-phenotype correlation remains unclear due to its highly variable phenotypic expressivity. Thus, genetic findings remain an essential tool in diagnosing IP, and understanding its genetic profile allows a greater possibility for personalized treatment. IP is slowly and gradually gaining attention in research, but there is much that remains to be understood. This review highlights the progress that has been made in IP including the different types of mutations detected in various populations, current diagnostic strategies, IKBKG pathophysiology, genotype-phenotype correlation, and treatment strategies, which provide insights into understanding this rare mendelian disorder.

Retinal Neovascularization in Two Patients with Incontinentia Pigmenti

Incontinentia pigmenti (IP) is a rare genodermatosis, inherited in an X-linked dominant pattern, making it generally found among women. Among several characteristics of IP are four phases of skin manifestation that tend to follow Blaschko's lines, in addition to abnormalities of the eye, central nervous system (CNS), and teeth. Ocular involvement in IP patients can occur since birth, which can be classified into retinal or non-retinal disorders. Retinal disorders can result in detachment, which is a major ocular threat for IP patients. This article reports two IP cases with overlapped phases of skin disorders in baby girls with ocular manifestations since early life. Clinical signs and additional examination of the skin and eyes are utilized to make the diagnosis. All the features of the histopathological examination supported the diagnosis of IP, and ocular exams revealed abnormalities in the form of retinal neovascularization (RN). Although RN may resolve spontaneously, patients should be monitored for the development of other eye disorders such as visual impairment.

Human Genetic Diseases Linked to the Absence of NEMO: An Obligatory Somatic Mosaic Disorder in Male

De novo somatic mutations are well documented in diseases such as neoplasia but are rarely reported in rare diseases. Hovewer, severe genetic diseases that are not compatible with embryonic development are caused exclusively by deleterious mutations that could only be found as mosaic and not as inherited mutations. We will review here the paradigmatic case of Incontinentia Pigmenti, a rare X-linked dominant disease caused by deficiency of the NEMO (also called IKKgamma) protein, which plays a pivotal role in tissue homeostasis. The loss-of-function mutations of NEMO are embryonically lethal in males while females survive because of unbalanced X-inactivation due to NEMO wild type (WT) expressing cells survival despite of NEMO mutant expressing cells. The few surviving IP males are obligatory mosaic mutants with the typical clinical presentation of IP in female. Indeed, the IP pathogenesis in the female and most likely also in the male somatic mosaics is based on the cellular effects of an impaired NEMO activity, but in the context of the interaction of genetically different cells in the affected tissue, which might underline the inflammatory status.

Phänotypisches und genetisches Spektrum von Incontinentia pigmenti – eine große Fallserie

HINTERGRUND

Incontinentia pigmenti ist eine seltene X-chromosomal dominant vererbte Systemerkrankung, die vor allem die Haut, aber auch andere neuroektodermale Gewebe wie Zähne, Haare, Augen und das zentrale Nervensystem betrifft.

PATIENTEN UND METHODIK

Diese multizentrische Fallserienstudie wurde an drei europäischen Hautkliniken durchgeführt und umfasste 30 Patienten mit Incontinentia pigmenti. Zwanzig Patienten wurden klinisch und genetisch untersucht, weitere zehn nur genetisch.

ERGEBNISSE

Die Studie umfasste 28 Frauen und zwei Männer mit einem medianen Alter von drei Jahren. Kutane Manifestationen zeigten sich bei allen 20 Patienten mit klinischen Daten. Stadium I wurde in 90 % dieser Patienten beobachtet. Stadium IV wurde bereits im Alter von einem Jahr beobachtet. Zahn- (81 %), Haar- (78 %) und neurologische Anomalien (53 %) waren häufiger als in bisherigen Berichten. Vierzehn Hautbiopsien zeigten typische Merkmale des entsprechenden Stadiums. Genetische Tests wurden bei 24 Patienten durchgeführt, von denen 14 die häufige Exon 4-10-Deletion und sieben andere pathogene Varianten aufwiesen, darunter drei unveröffentlichte Mutationen. In drei weiteren Fällen wurden keine genetischen Veränderungen gefunden.

SCHLUSSFOLGERUNGEN

In dieser Studie reichte der Phänotyp von lediglich subtil ausgeprägter Hautbeteiligung bis hin zu schweren Multisystemerkrankungen. Die extrakutane Beteiligung sollte zum Zeitpunkt der Diagnose und in regelmäßigen Abständen evaluiert werden, da sich einige Manifestationen erst mit der Zeit entwickeln.

SUMMARY

Background and objectives Incontinentia pigmenti is a rare X-linked dominantly inherited systemic disease affecting primarily the skin but also other neuroectodermal tissues such as teeth, hair, eyes, and the central nervous system. Patients and methods This multicenter case series study was conducted at three European departments of Dermatology including 30 patients with incontinentia pigmenti. Twenty patients were evaluated clinically and genetically, another ten only genetically. Results The study included 28 females and two males with a median age of three years. Cutaneous manifestations were present in all 20 patients with clinical data. Stage I was observed in 90 % of those patients. Stage IV was observed as early as one year of age. Dental (81 %), hair (78 %) and neurological anomalies (53 %) were more frequent than previously reported. Fourteen skin biopsies showed typical features of the corresponding stage. Genetic testing of 24 patients revealed the common exon 4-10 deletion in 14 cases and seven other pathogenic variants, including three unpublished mutations. In another three cases, no genetic alterations were found. Conclusions In this study, the phenotype ranged from only subtle cutaneous involvement to severe multisystemic disorders. Extracutaneous involvement should be evaluated at the time of diagnosis and in regular intervals, as some manifestations may develop over time.

Phenotypic and genetic spectrum of incontinentia pigmenti - a large case series

BACKGROUND AND OBJECTIVES

Incontinentia pigmenti is a rare X-linked dominantly inherited systemic disease affecting primarily the skin but also other neuroectodermal tissues such as teeth, hair, eyes, and the central nervous system.

PATIENTS AND METHODS

This multicenter case series study was conducted at three European departments of Dermatology including 30 patients with incontinentia pigmenti. Twenty patients were evaluated clinically and genetically, another ten only genetically.

RESULTS

The study included 28 females and two males with a median age of three years. Cutaneous manifestations were present in all 20 patients with clinical data. Stage I was observed in 90 % of those patients. Stage IV was observed as early as one year of age. Dental (81 %), hair (78 %) and neurological anomalies (53 %) were more frequent than previously reported. Fourteen skin biopsies showed typical features of the corresponding stage. Genetic testing of 24 patients revealed the common exon 4-10 deletion in 14 cases and seven other pathogenic variants, including three unpublished mutations. In another three cases, no genetic alterations were found.

CONCLUSIONS

In this study, the phenotype ranged from only subtle cutaneous involvement to severe multisystemic disorders. Extracutaneous involvement should be evaluated at the time of diagnosis and in regular intervals, as some manifestations may develop over time.

Congenital Pigmentary Anomalies in the Newborn

Congenital pigmentary anomalies may be evident at birth or soon after, with some birthmarks becoming apparent later in infancy or early childhood. It is important to recognize various pigmentary anomalies in the neonate, most of which are benign but a subset of which are associated with cutaneous morbidity or systemic ramifications and require further evaluation. This review will focus on pigmentary mosaicism, congenital melanocytic nevi, nevus spilus, dermal melanocytosis, and pigmentary anomalies associated with neurofibromatosis type 1 (café au lait spots, freckling, plexiform neurofibromas, nevus anemicus), tuberous sclerosis (hypomelanotic macules), and incontinentia pigmenti.

Development of dentofacial characteristics related to Incontinentia Pigmenti syndrome: A repeated cross-sectional study

INTRODUCTION

This research aimed to investigate the dentofacial characteristics of patients with Incontinentia Pigmenti (IP) (or Bloch-Sulzberger) syndrome in childhood, juvenile, and adulthood developmental stages.

METHODS

Fifteen female patients with a clinical diagnosis of IP, genetically confirmed by molecular testing, were included in this study. The records of 25 nonsyndromic females with Class I occlusion and lateral cephalograms obtained at similar developmental stages were selected from the American Association of Orthodontists Foundation Legacy Collection as a control group. Dentofacial features of subjects with IP and those in the control group were compared statistically using t test and Mann-Whitney rank-sum test (significance was defined as P <0.05).

RESULTS

In general, patients with IP had shorter maxillary and mandibular length, straight skeletal profile, hypodivergent growth pattern with a tendency to mandibular protrusion, shorter anterior facial height, Class III compensatory positioning of incisors, more retruded lips, and smaller maxillary incisor exposure. The degree of hypodontia severity had a significant impact on skeletal, dental, and soft-tissue features in patients with IP.

CONCLUSIONS

The results of this study showed that, since childhood, the dentofacial characteristics of patients with IP were progressively distancing from those of nonsyndromic patients with Class I occlusion, presenting their own orthodontic needs.