Optic neuropathy in methylmalonic acidemia and propionic acidemia

Area of Science:

• Biochemistry
• Genetics
• Ophthalmology

Background:

• Methylmalonic acidemia (MMA) and propionic acidemia (PA) are rare inherited metabolic disorders.
• Optic neuropathy (ON) is an emerging complication in these conditions, often reported in isolated cases.

Purpose of the Study:

• To report the clinical features and visual outcomes of pediatric patients with MMA or PA and optic neuropathy.
• To highlight the under-reporting and clinical presentation of ON in these rare metabolic disorders.

Main Methods:

• Retrospective observational case series.
• Analysis of 53 patients with MMA or PA, of whom 12 underwent ophthalmic review.
• Clinical assessment and electrodiagnostic testing for optic neuropathy.

Main Results:

• Seven patients presented with clinical findings consistent with ON.
• Visual outcomes were generally poor, with slow progression or stability in most cases.
• Acute presentations occurred during metabolic crises, and electrodiagnostics indicated photoreceptor involvement.

Conclusions:

• ON is likely under-reported in patients with MMA and PA.
• Clinical presentation of ON can be acute or insidious, with metabolic decompensation potentially triggering vision loss.
• Active clinical surveillance is crucial for early diagnosis and management, considering potential comorbidities and cognitive impairment.