Multiple Mitochondrial Dysfunction Syndrome Type 3: Presentation With Acute Postinfectious Seizures and Literature Review

Multiple mitochondrial dysfunction syndrome type 3 (MMDS3) represents a rare autosomal recessive mitochondrial disorder arising from biallelic pathogenic variants in IBA57 , a core gene responsible for the late-stage assembly and insertion of mitochondrial 4Fe-4S iron-sulfur clusters. We report a male patient diagnosed with MMDS3. Whole-exome sequencing identified compound heterozygous IBA57 variants: c.286T>C (p.Tyr96His) and a novel unreported variant c.754G>A (p.Gly252Ser). The patient initially presented with motor developmental regression at 9 months of age and experienced infection-triggered neurologic exacerbation at the age of 4 years 9 months, complicated by non-convulsive status epilepticus (NCSE) and rapid neurologic deterioration. Following standardized comprehensive management, his seizures were fully controlled, and motor function gradually improved during long-term follow-up. This study further expands the genotypic and phenotypic spectrum of MMDS3, and highlights the potential risk of acute neurologic deterioration triggered by infection in IBA57 -related disorders. Combined with a systematic literature review, our findings provide reliable clinical references for early recognition, standardized therapy and genetic counseling of this rare mitochondrial disease.