# A Rare Diagnosis in a Resource-Limited Setting: Alkaptonuria in a Young Dominican Child

## TL;DR

A young child in the Dominican Republic was diagnosed with alkaptonuria, a rare genetic disorder, highlighting the need for early detection and specialized care in resource-limited areas.

## Contribution

This case report highlights the successful diagnosis and management of alkaptonuria in a low-resource setting using exome sequencing and multidisciplinary care.

## Key findings

- A 3-year-old boy was diagnosed with alkaptonuria through urine testing and exome sequencing.
- Two heterozygous pathogenic variants in the HGD gene were identified.
- Management included dietary restrictions and vitamin C supplementation to mitigate complications.

## Abstract

Alkaptonuria (AKU) is a rare metabolic genetic disorder transmitted in an autosomal recessive pattern caused by a deficiency in the activity of the enzyme homogentisate 1,2-dioxygenase (HGD), leading to progressive accumulation of oxidized homogentisic acid (HGA) as a dark pigment in connective tissues, cartilage, and organs in a process called ochronosis. Polymerization of HGA causes urine darkening after a few hours of exposure to the atmosphere, which is a hallmark of AKU. We present the case of a 3-year-old boy from a rural community in the Dominican Republic assessed at the pediatric hospital due to dark urine. The patient was directed to urology for suspicion of hematuria and later referred to the genetic pediatrics department in the absence of bleeding or urologic structural abnormalities. Afterward, a qualitative urine test and subsequent molecular testing via exome sequencing identified two heterozygous pathogenic variants in the HGD gene. Management consisted of a protein-restricted diet and vitamin C supplementation as an antioxidant. This case report emphasizes the importance of early detection and referral to a pediatric geneticist for prompt management, utilizing a multidisciplinary approach, to prevent complications and address the challenges associated with diagnosis and treatment in resource-limited settings and low-income families.