Propionic Acidemia and Optic Neuropathy: A Report of Two Cases

Abstract

Introduction: Propionic acidemia is a metabolic disease produced by a deficiency of the enzyme propionylCoA carboxylase. It can lead to coma, with severe neurologic encephalopathy or present later in life with vomiting, hypotonia, and seizures. An early diagnosis with adequate treatment helps to prevent the sequelae. Among the described complications is optic neuropathy, although not commonly reported, it is very disabling. Objectives: To describe two patients with propionic acidemia and optic neuropathy. Patients and Methods: Patient 1: 16 years old, male, parents without consanguinity. He was diagnosed at 5 months of age because of hypotonia and seizures. Until the age of 9 years, he evolved satisfactorily; therefore, he stopped treatment. At 13 years, he presented bilateral optic neuropathy. Patient 2: 20 years, female, parents without consanguinity. She was diagnosed with PA at 11 months of age because of hypotonia and seizures. She evolved satisfactorily until the age of 9 years when she presented a metabolic decompensation followed by a bad metabolic control. At 18 years, she presented bilateral progressive optic neuropathy. Results: Both patients have psychometric scores with borderline IQ 84-75 (WISC-R) beside optic neuropathy. They were evaluated by an ophthalmologist and also by neuroimaging (MRI of optic pathway). Conclusions: Pathophysiology of optic neuropathy is not completely understood. There is evidence that the damage is due to an accumulation of neurotoxic compounds secondary to the metabolic block increasing the oxidative stress. We suggest an annual ophthalmologic evaluation in the longterm follow-up of organic acidurias with visual loss, in order to detect this disabling sequela at an earlier stage.

Propionyl-CoA carboxylase – A review

“…Some individuals also suffered from acute psychotic episodes [99]. Neurological complications in individuals with PA include seizures of which generalized tonic-clonic is the most common type, metabolic stroke- like episode that mainly affects basal ganglia and optic nerve atrophy [100, 101]. Some individuals present with only movement disorders without metabolic decompensations [102].…”

Methylmalonic and propionic acidemias: clinical management update

“…In MMA, these childhood and adolescent-onset patients may present with chronic renal failure, and evaluation for MMA should occur in all patients who present with progressive proximal tubular renal dysfunction [60–64]. Late-stage presentation of PA may include seemingly isolated cardiomyopathy, while patients with PA and MMA may present with progressive spastic quadraparesis, progressive movement disorder, or vision loss [6, 7, 14, 32, 33, 35, 58, 65–71]. Some patients who self-restrict protein due limited protein tolerance may present later in life with metabolic decompensation or metabolic stroke following a surgical or interventional procedure where fasting for several hours is required.…”

Optic neuropathy in methylmalonic acidemia and propionic acidemia

“…Older patients in the literature have mostly presented acutely with centro-cecal defects, temporal pallor and ultimately profound bilateral visual loss that has been compared with Leber's hereditary optic neuropathy (LHON) 5 7 8. Younger patients in the literature, and the five males in our paediatric series, presented with progressive or undetermined visual deterioration, which may in part reflect the younger age and increased difficulty in reporting visual changes.…”