Rare variant of Lesch-Nyhan syndrome without self-mutilation or nephrolithiasis

Catching the Culprit: How Chorea May Signal an Inborn Error of Metabolism

Background

Movement disorders, particularly chorea, are uncommon in inborn errors of metabolism, but their identification is essential for improved clinical outcomes. In this context, comprehensive descriptions of movement disorders are limited and primarily derived from single cases or small patient series, highlighting the need for increased awareness and additional research in this field.

Methods

A systematic review was conducted using the MEDLINE database and GeneReviews. The search included studies on inborn errors of metabolism associated with chorea, athetosis, or ballismus. The review adhered to PRISMA guidelines.

Results

The systematic review analyzed 76 studies out of 2350 records, encompassing the period from 1964 to 2022. Chorea was observed in 90.1% of the 173 patients, followed by athetosis in 5.7%. Various inborn errors of metabolism showed an association with chorea, with trace elements and metals being the most frequent. Cognitive and developmental abnormalities were common in the cohort. Frequent neurological features included seizures, dysarthria, and optic atrophy, whereas non-neurological features included, among others, facial dysmorphia and failure to thrive. Neuroimaging and biochemical testing played crucial roles in aiding diagnosis, revealing abnormal findings in 34.1% and 47.9% of patients, respectively. However, symptomatic treatment efficacy for movement disorders was limited.

Discussion

This study emphasizes the complexities of chorea in inborn errors of metabolism. A systematic approach with red flags, biochemical testing, and neuroimaging is required for diagnosis. Collaboration between neurologists, geneticists, and metabolic specialists is crucial for improving early detection and individualized treatment. Utilizing genetic testing technologies and potential therapeutic avenues can aid in the improvement of patient outcomes.

Hypoxanthine-guanine phosphoribosyltransferase deficiency in a patient with a Madrid II mutation

The hypoxanthine-guanine phosphoribosyltransferase deficiency is an inborn error of purine metabolism, linked to the X chromosome. The clinical phenotypes associated with HPRT deficiency varied according to the level of enzyme deficiency, with a large spectrum of neurologic features like self-injurious behaviour in patients with complete deficiency. We report a 20-year-old man who had asymmetric polyarthritis, tophi, hyperuricemia, nephrolithiasis and mild neurologic symptoms with undetectable levels of HPRT activity in lysed erythrocytes. The genetic study identified the c.143G>A mutation in exon 3, GAA CGT (CTT>GAA CAT CTT (48arg>his). The presence of gouty arthropathy and chronic hyperuricemia in a young patient with neurological symptoms, suggests HPRT deficiency for which it is necessary its enzyme and molecular determination.