# Genotype-Phenotype Delineation of Autoimmune Polyendocrinopathy, Candidiasis, and Ectodermal Dystrophy in a Pediatric Patient: A Case Report

## TL;DR

This case report describes a rare genetic disorder in a child from Lebanon, involving immune system dysfunction and multiple symptoms.

## Contribution

The study identifies a novel AIRE gene mutation and expands the known phenotypic spectrum of this rare disorder.

## Key findings

- Exome sequencing confirmed a novel homozygous pathogenic variant in the AIRE gene.
- The patient exhibited chronic mucocutaneous candidiasis, enamel hypoplasia, and hepatitis.
- The findings expand the genotypic and phenotypic understanding of this rare immune disorder.

## Abstract

Background/Objectives: Autoimmune Polyendocrinopathy with Candidiasis and Ectodermal Dystrophy is an extremely rare autosomal recessive disorder caused by inborn errors of immunity. It is due to a loss-of-function mutation in the AIRE autoimmune regulator gene. Its manifestations include autoimmunity affecting endocrine glands, in addition to non-endocrine manifestations including dental enamel hypoplasia, alopecia areata, hepatitis, and chronic mucocutaneous candidiasis. Globally, 10 cases per million are affected by this condition, with higher incidence in highly consanguineous populations. Here, we describe a novel AIRE gene mutation in a pediatric patient from Lebanon, along with the observed phenotype. Method: A nine-year-old boy with history of craniosynostosis presented with jaundice. His past medical history was significant for recurrent oral thrush, keratoconjunctivitis, nail dystrophy, and alopecia. Upon presentation, he had jaundice, isolated splenomegaly, and severe failure to thrive. Laboratory tests showed transaminitis, cholestasis, and hypergammaglobulinemia. Abdominal ultrasound findings were suggestive of cirrhosis with compensated portal hypertension. The differential diagnosis included viral infection, inborn errors of metabolism, and autoimmune hepatitis. Results: Exome sequencing identified a novel homozygous pathogenic variant in the AIRE gene, NM_000383.4: c.1066dup p.(Arg356Profs*16), confirming the diagnosis. Conclusions: This study expands the genotypic and phenotypic spectrum of a rare inborn error of immunity in a child with chronic mucocutaneous candidiasis, enamel hypoplasia, and hepatitis.