Pseudodendritic keratitis in citrullinemia; a report of an unusual and novel ocular finding in this metabolic disorder

Abstract

Purpose: To report a 15 year old girl with citrullinemia type 1 and 2 accompanied by neurologic signs and symptoms and a novel ocular complaint in cornea like tyrosinemia type 2. Observations: A 15 year old female was admitted with decreased consciousness and neurologic signs and symptoms. Citrulinemia was discovered through metabolic testing. Later genetic studies revealed mutations in both ASS1 and SLC25A13 genes. Two years after the first presentation, the patient was re-admitted with complaints of bilateral photophobia and tearing. Biomicroscopic examination revealed bilateral corneal haziness with pseudodendritic lesions like tyrosinemia type 2 that were subsided with protein restriction and the use of urea cycle disease (UCD) formula. Conclusions and importance: Citrullinemia is the inherited autosomal recessive disorder of urea cycle that leads to ammonia and accumulation of other toxic substances in the blood. Two types of Citrullinemia have been defined. Citrullinemia type 1, caused by deficiency or reduction in argininosuccinate synthetase enzyme activity due to damaging mutation in ASS1 gene. Citrullinemia type 2 as another subtype is caused by the absence or dysfunction of the mitochondrial membrane carrier protein (SLC25A13), also called CITRIN. Pseudodendritic keratitis is a rare condition that may be seen with tyrosinemia type 2. The association of this ocular complaint with citrullinemia has not been described previously. Awareness of this phenomenon may improve the diagnosis and management of citrullinemia patients.

Keywords

• Citrullinemia
• Pseudodendritic keratitis
• Tyrosinemia