# Severe Neurological Sequelae and Radiological Findings in a Lost-to-Follow-Up Case of Hyperornithinemia-Hyperammonemia-Homocitrullinuria Syndrome

## TL;DR

A child with a rare metabolic disorder stopped treatment due to socioeconomic issues and suffered severe neurological damage by age 12.

## Contribution

This case emphasizes the need for continuous care and social support to prevent irreversible complications in HHH syndrome.

## Key findings

- The patient developed global developmental delay and refractory epilepsy due to lack of follow-up.
- Radiological findings showed corpus callosal atrophy and signs of hepatic dysfunction.
- The case underscores the importance of sustained treatment and multidisciplinary care in HHH syndrome.

## Abstract

Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is a rare autosomal recessive urea cycle disorder caused by defective hepatic ornithine transport, leading to hyperammonemia and progressive neurological complications. We report the case of a patient who was treated for hyperammonemic crisis at birth and subsequently diagnosed with HHH syndrome. Management, including ammonia-lowering therapy and a low-protein diet, was initiated; however, due to significant socioeconomic barriers, he was lost to follow-up from the age of two. He re-presented at the age of 12 in a severely debilitated state with global developmental delay and refractory epilepsy. Investigations demonstrated radiological evidence of neurological damage, including corpus callosal atrophy, alongside biochemical and ultrasonographic features of hepatic dysfunction. This case highlights the critical importance of sustained treatment, multidisciplinary follow-up, and adequate social support in preventing irreversible complications of HHH syndrome.