Incontinentia pigmenti (Bloch–Sulzberger syndrome)

Multiple Congenital Anomalies-Hypotonia-Seizures Syndrome 2 Caused by a Novel PIGA Variant Not Associated with a Skewed X-Inactivation Pattern

Germline variants in the phosphatidylinositol glycan class A (PIGA) gene, which is involved in glycosylphosphatidylinositol (GPI) biosynthesis, cause multiple congenital anomalies-hypotonia-seizures syndrome 2 (MCAHS2) with X-linked recessive inheritance. The available literature has described a pattern of almost 100% X-chromosome inactivation in mothers carrying PIGA variants. Here, we report a male infant with MCAHS2 caused by a novel PIGA variant inherited from his mother, who has a non-skewed pattern of X inactivation. Phenotypic evidence supporting the pathogenicity of the variant was obtained by flow-cytometry tests. We propose that the assessment in neutrophils of the expression of GPI-anchored proteins (GPI-APs), especially CD16, should be considered in cases with variants of unknown significance with random X-inactivation in carrier mothers in order to clarify the pathogenic role of PIGA or other gene variants linked to the synthesis of GPI-APs.

A case report of neonatal incontinentia pigmenti complicated by severe cerebrovascular lesions in one of the male monozygotic twins

Background

This article reports a case of neonatal incontinentia pigmenti onset in only one male monozygotic twin with characteristic skin lesions after birth followed by severe cerebrovascular lesions.

Case presentation

A male infant, the first of monozygotic twins, was born with multiple yellow pustules all over his body, repeated new herpes at different sites during the course of the disease, aggravated by fusion, warty crusts, and hyperpigmentation; biopsy pathology suggested eosinophilic spongiform edema of the skin. Peripheral blood eosinophils were significantly elevated, and brain magnetic resonance imaging revealed diffuse multiple cystic and lamellar abnormal signal areas in the left frontal and parietal lobes. On day 30, the infant showed neurological symptoms, such as poor response and apnea, and an emergency cranial computed tomography scan revealed abnormal changes in the left cerebral hemisphere and bilateral cerebellum. After admission, he was given a potassium permanganate bath and topical mupirocin for 1 month, and the skin abnormalities improved. He was treated with mechanical ventilation and vasoactive drugs for 2 days after the cerebrovascular accident, and died the same day after the parents chose hospice care. No deletion variants or point mutations were detected in subsequent genetic tests, and chromosomal copy number variation tests revealed different degrees of chimeric duplications and deletions in different regions of chromosomes Y and 3. The parents were healthy, and his twin brother had normal growth and development with no abnormalities at multiple follow-up visits.

Conclusion

Neonatal incontinentia pigmenti in only one male monozygotic twin is extremely rare and the genetic diagnosis is challenging. Awareness of the combined cerebrovascular lesions needs to be enhanced, and potential prevention and treatment methods need to be explored to improve the prognosis.

NEMO reshapes the α-Synuclein aggregate interface and acts as an autophagy adapter by co-condensation with p62

NEMO is a ubiquitin-binding protein which regulates canonical NF-κB pathway activation in innate immune signaling, cell death regulation and host-pathogen interactions. Here we identify an NF-κB-independent function of NEMO in proteostasis regulation by promoting autophagosomal clearance of protein aggregates. NEMO-deficient cells accumulate misfolded proteins upon proteotoxic stress and are vulnerable to proteostasis challenges. Moreover, a patient with a mutation in the NEMO-encoding IKBKG gene resulting in defective binding of NEMO to linear ubiquitin chains, developed a widespread mixed brain proteinopathy, including α-synuclein, tau and TDP-43 pathology. NEMO amplifies linear ubiquitylation at α-synuclein aggregates and promotes the local concentration of p62 into foci. In vitro, NEMO lowers the threshold concentrations required for ubiquitin-dependent phase transition of p62. In summary, NEMO reshapes the aggregate surface for efficient autophagosomal clearance by providing a mobile phase at the aggregate interphase favoring co-condensation with p62.

Oral Rehabilitation as Part of a Multidisciplinary Treatment in a Case Study of Pigmentary Incontinence

We present the clinical course of a 9-year-old female patient with Bloch-Sulzberger syndrome and severe neurological deficit that met the major (classic cutaneous signs) and minor (dental anomalies and retinal pathology) diagnostic criteria of Landy and Donnai. Longitudinal multidisciplinary follow-up was carried out from birth to adulthood. Neurological involvement was assessed with electroencephalographic (EEG) and neuroimaging tests at different times during the patient's life. Cranio-maxillofacial involvement was evaluated using lateral skeletal facial and cephalometric analyses. The right and left facial widths were measured through frontal face analysis and using the vertical zygomatic-midline distance. Oral rehabilitation was performed through orthodontic treatment and major dental reconstruction using composite resins. This treatment aimed to improve the occlusion and masticatory function, relieve the transversal compression of the maxilla, and reconstruct the fractured teeth. We believe that, due to significant neurological and cognitive impairment, orthognathic surgery was not the best option for restoring function and improving oral health-related quality of life.

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.

Cerebral angiogenesis ameliorates pathological disorders in Nemo-deficient mice with small-vessel disease

Cerebral small-vessel diseases (SVDs) often follow a progressive course. Little is known about the function of angiogenesis, which potentially induces regression of SVDs. Here, we investigated angiogenesis in a mouse model of incontinentia pigmenti (IP), a genetic disease comprising features of SVD. IP is caused by inactivating mutations of Nemo, the essential component of NF-κB signaling. When deleting Nemo in the majority of brain endothelial cells (Nemo^beKO mice), the transcriptional profile of vessels indicated cell proliferation. Brain endothelial cells expressed Ki67 and showed signs of DNA synthesis. In addition to cell proliferation, we observed sprouting and intussusceptive angiogenesis in Nemo^beKO mice. Angiogenesis occurred in all segments of the vasculature and in proximity to vessel rarefaction and tissue hypoxia. Apparently, NEMO was required for productive angiogenesis because endothelial cells that had escaped Nemo inactivation showed a higher proliferation rate than Nemo-deficient cells. Therefore, newborn endothelial cells were particularly vulnerable to ongoing recombination. When we interfered with productive angiogenesis by inducing ongoing ablation of Nemo, mice did not recover from IP manifestations but rather showed severe functional deficits. In summary, the data demonstrate that angiogenesis is present in this model of SVD and suggest that it may counterbalance the loss of vessels.

Retinal Manifestations of Incontinentia Pigmenti: A Case Series of 14 Patients Highlighting the Importance of Intravenous Fluorescein Angiography and the Benefits of Early Laser Photocoagulation

Purpose:

This case series describes the nature and frequency of retinal manifestations in patients with incontinentia pigmenti (IP).

Methods:

This is a retrospective single-center case series of all known patients with IP who presented to Associated Retina Consultants (Phoenix, AZ) between May 2016 and April 2019. Twenty-eight eyes of 14 patients with a dermatologic diagnosis of IP were included (n = 28). Most patients underwent examination under anesthesia with fundus photographs and intravenous fluorescein angiography (IVFA).

Results:

Of the 28 eyes, 8 (28.6%) had abnormal retinal findings on fundus examination. Of the 26 eyes that had IVFA, 10 (38.5%) had abnormal findings: Seven eyes (26.9%) had peripheral ischemia, 2 (7.7%) had previous peripheral laser scarring, and 2 (7.7%) had active peripheral neovascularization. Three eyes with normal examination results were found to have mild ischemia by IVFA. Patients with ischemia confirmed by IVFA were treated with laser photocoagulation. During follow-up, 4 previously treated eyes received additional laser photocoagulation. No patients showed vision loss, vitreous hemorrhage, retinal detachment, or adverse effects of treatment. No patients required vitreoretinal surgery.

Conclusions:

IP is a potentially blinding disease. Our case series demonstrates the efficacy of early treatment and the importance of ancillary testing with IVFA and fundus photography.

Incontinentia pigmenti: Generation of an IKBKG deficient human iPSC line (KICRi002-A-1) on a 46,XY background using CRISPR/Cas9

Incontinentia pigmenti (IP) is an X-linked dominant neuroectodermal dysplasia caused by loss-of-function mutations in the IKBKG gene. Using CRISPR/Cas9 technology, we generated an IKBKG knock-out iPSC line (KICRi002-A-1) on a 46,XY background. The iPSC line showed a normal karyotype, expressed pluripotency markers and exhibited capability to differentiate into the three germ layers in vitro. Off-target editing was excluded and no IKBKG mRNA expression could be detected. Our line offers a useful resource to elucidate mechanisms caused by IKBKG deficiency that leads to disrupted male fetal development and for drug screening to improve treatment of female patients with IP.