Expanding the clinical phenotype associated with NIPAL4 mutation: Study of a Tunisian consanguineous family with erythrokeratodermia variabilis-Like Autosomal Recessive Congenital Ichthyosis

PLoS One. 2021 Oct 20;16(10):e0258777. doi: 10.1371/journal.pone.0258777. eCollection 2021.

Abstract

Erythrokeratodermia variabilis (EKV) is a rare disorder of cornification usually associated with dominant mutations in the GJB3 and GJB4 genes encoding connexins (Cx)31 and 30.3. Genetic heterogeneity of EKV has already been suggested. We investigated at the clinical and genetic level a consanguineous Tunisian family with 2 sisters presenting an autosomal recessive form of EKV to better characterize this disease. Mutational analysis initially screened the connexin genes and Whole-exome sequencing (WES) was performed to identify the molecular aetiology of the particular EKV phenotype in the proband. Migratory shaped erythematous areas are the initial presenting sign followed by relatively stable hyperkeratotic plaques are the two predominates characteristics in both patients. However, remarkable variability of morphological and dominating features of the disease were observed between patients. In particular, the younger sister (proband) exhibited ichthyosiform-like appearance suggesting Autosomal Recessive Congenital Ichthyosis (ARCI) condition. No causative mutations were detected in the GJB3 and GJB4 genes. WES results revealed a novel missense homozygous mutation in NIPAL4 gene (c.835C>G, p.Pro279Ala) in both patients. This variant is predicted to be likely pathogenic. In addition, in silico analysis of the mutated 3D domain structure predicted that this variant would result in NIPA4 protein destabilization and Mg2+ transport perturbation, pointing out the potential role of NIPAL4 gene in the development and maintenance of the barrier function of the epidermis. Taken togheter, these results expand the clinical phenotype associated with NIPAL4 mutation and reinforce our hypothesis of NIPAL4 as the main candidate gene for the EKV-like ARCI phenotype.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Child
  • Connexins / genetics
  • Consanguinity
  • Erythrokeratodermia Variabilis / genetics*
  • Exome Sequencing / methods*
  • Female
  • Humans
  • Infant
  • Molecular Docking Simulation
  • Mutation, Missense*
  • Pedigree
  • Phenotype
  • Protein Stability
  • Receptors, Cell Surface / chemistry*
  • Receptors, Cell Surface / genetics*
  • Tunisia

Substances

  • Connexins
  • NIPAL4 protein, human
  • Receptors, Cell Surface
  • GJB3 protein, human
  • connexin 30.3

Grants and funding

This work was supported by the Tunisian Ministry of Public Health and the Ministry of Higher Education and Scientific Research (LR20IPT05). Laroussi N. is recipient of a Mobidoc Fellowship under the Programme d’Appui au Système de recherche et d’Innovation (PASRI funded by the European Commission Program-Europe Aid). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.