Incontinentia Pigmenti with Persistent Hypercalcemia: Case Report

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.

Rare Causes of Hypercalcemia: 2021 Update

CONTEXT

Primary hyperparathyroidism and malignancy are the etiologies in 90% of cases of hypercalcemia. When these entities are not the etiology of hypercalcemia, uncommon conditions need to be considered. In 2005, Jacobs and Bilezikian published a clinical review of rare causes of hypercalcemia, focusing on mechanisms and pathophysiology. This review is an updated synopsis of rare causes of hypercalcemia, extending the observations of the original article.

EVIDENCE ACQUISITION

Articles reporting rare associations between hypercalcemia and unusual conditions were identified through a comprehensive extensive PubMed-based search using the search terms "hypercalcemia" and "etiology," as well as examining the references in the identified case reports. We categorized the reports by adults vs pediatric and further categorized the adult reports based on etiology. Some included reports lacked definitive assessment of etiology and are reported as unknown mechanism with discussion of likely etiology.

EVIDENCE SYNTHESIS

There is a growing understanding of the breadth of unusual causes of hypercalcemia. When the cause of hypercalcemia is elusive, a focus on mechanism and review of prior reported cases is key to successful determination of the etiology.

CONCLUSIONS

The ever-expanding reports of patients with rare and even unknown mechanisms of hypercalcemia illustrate the need for continued investigation into the complexities of human calcium metabolism.

Incontinentia pigmenti in boys: Causes and consequences

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.