Child with adenylosuccinate lyase deficiency caused by a novel complex heterozygous mutation in the ADSL gene: A case report.

BACKGROUND: Adenylosuccinate lyase (ADSL) deficiency is a rare autosomal-recessive defect of purine metabolism caused by mutation of the ADSL gene. It can cause severe neurological impairment and diverse clinical manifestations, including epilepsy. CASE SUMMARY: Here, we describe a 3-year-old Chinese boy who had both psychomotor retardation and refractory epilepsy. Magnetic resonance imaging showed myelin hypoplasia. Electroencephalography findings supported a diagnosis of epilepsy. Whole-exon sequencing revealed the presence of a novel complex heterozygous mutation in the ADSL gene: The splicing mutation c.154-3C>G and the missense mutation c.71C>T (p. Pro24Leu). Considering the patient's clinical presentation and genetic test results, the complex heterozygous mutation was predicted to prevent both ADSL alleles from producing normal ADSL, which may have led to ADSL deficiency. Finally, the child was diagnosed with ADSL deficiency. CONCLUSION: We identified a novel complex heterozygous mutation in the ADSL gene associated with ADSL deficiency, thus expanding the known spectrum of pathogenic mutations that cause ADSL deficiency. Additionally, we describe epilepsy that occurs in patients with ADSL deficiency.