Objective: To report the clinical course, diagnostic evaluation, and genetic findings in a 24-year-old male with early childhood onset tremor, seizures ,bradykinesia and  rigidity , In addition to levodopa-induced dyskinesia.

Background: Early-onset Seizures-parkinsonism with levodopa-induced dyskinesia is a rare presentation. Genetic mutations, such as in the HPRT1 gene, can play a crucial role in the pathophysiology of Hyperkinetic Movement Disorders.

The HPRT1 gene encodes the enzyme hypoxanthine-guanine phosphoribosyl transferase 1 (HGPRT), essential for purine recycling in nucleotide metabolism. Mutations in HPRT1 can lead to varying degrees of enzyme deficiency, resulting in disorders such as Lesch-Nyhan syndrome (LNS) and hyperuricemia. LNS is characterized by hyperuricemia, choreoathetosis, and self-mutilating behaviors. To date, there have been no documented cases linking HPRT1 mutations to parkinsonism, seizures, or levodopa-induced dyskinesia.

This case highlights the diagnostic journey and clinical management of a young male with this presentation.

Method: A comprehensive clinical evaluation, brain MRI, EEG, routine laboratory tests, metabolic screening (serum pyruvate, lactate, copper, ceruloplasmin, and 24-hour urinary copper), and whole exome sequencing were conducted.

Results: The patient experienced tremors since the age of 4, with progressive bradykinesia and rigidity. He had a history of generalized tonic-clonic seizures from age 4, which recurred annually until the age of 15. Episodes of leg elevation with confusion and disturbed consciousness upon entering sleep were also reported. MRI and metabolic tests were unremarkable. Whole exome sequencing revealed a pathogenic mutation in the HPRT1 gene. Thus, reporting the first case presenting with early childhood onset Parkinsonism along with seizures in addition to levodopa induced dyskinesia related to mutation in this gene.

Conclusion: This case underscores the importance of genetic testing in diagnosing atypical parkinsonian syndromes, particularly in young patients with an unusual clinical presentation. Early genetic diagnosis can aid in personalized management and genetic counseling.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/hprt1-gene-mutation-in-a-young-male-with-early-childhood-onset-seizures-parkinsonism-and-levodopa-induced-dyskinesia-a-case-report/