# Case report: Whole exome sequencing identifies a novel variant in the HPRT1 gene in a male with developmental delay

## TL;DR

A new genetic variant in the HPRT1 gene was found in a man with developmental delay, confirming a rare genetic disorder called Lesch-Nyhan syndrome.

## Contribution

The study reports a novel hemizygous variant in the HPRT1 gene associated with Lesch-Nyhan syndrome.

## Key findings

- Whole exome sequencing identified a novel HPRT1 variant (c.104T > C) in a male with developmental delay and hyperuricemia.
- The variant is predicted to disrupt HGPRT activity, supporting a diagnosis of Lesch-Nyhan syndrome.
- This finding adds to the genetic understanding of Lesch-Nyhan syndrome and aids in genetic counseling.

## Abstract

Lesch-Nyhan syndrome (LNS, OMIM #300322) is a rare X-linked genetic disorder caused by variants in the HPRT1 gene, which codes for the Hypoxanthine-guanine phosphoribosyltransferase (HGPRT). HPRT1 gene variants disrupt normal purine metabolism, leading to the involvement of multiple organ systems, primarily characterized by hyperuricemia, dystonia, and neurological abnormalities, which makes LNS clinically heterogeneous and diagnostically challenging. Here, we report a rare case of a 27-year-old Chinese male exhibiting severe lower limb motor disorders, hyperuricemia, and intellectual development delay. Blood tests showed hyperuricemia and whole exome sequencing (WES) identified a novel hemizygous variant in the HPRT1 (NM-000194.3) gene: c.104T > C in exon 2, respectively. Bioinformatics techniques indicated that the variant may disrupt the activity of HGPRT. According to the clinical presentation, diagnostic examination, and WES results, the patient was finally diagnosed with LNS. This study identified a previously unreported pathogenic variant in the HPRT1 gene. Although no curative therapy is currently available for HPRT1 gene variants at present, a definite diagnosis of its genetic etiology is of great significance for genetic counseling and family planning.