Management of adult-onset methylmalonic acidemia with hypotonia and acute respiratory failure

Abstract

Rationale:Methylmalonic acidemia (MMA) is an autosomal recessive disease of organic acidemia.Patient concerns:We report a 26-year-old male who presented with metabolic acidosis, acute renal failure required hemodialysis and acute respiratory failure required mechanical ventilation support. Progressive hypotonia of muscles made weaning from mechanical ventilator difficult.Diagnoses:High level of serum methylmalonic acid and the mut genotype sequences confirmed the diagnosis of this adult-onset MMA. Two mut genotype sequences were found by analyzing all coding exons and exon-intron junctions. One genotype was well documented (Exon 6 Mutation, c. 1280G>A. p. G427D, heterozygous). The other mut genotype sequence had never been reported elsewhere (Intron 6 Novel, c. 1333-13_c. 1333-8delTTTTTC, heterozygous).Interventions:Diet modification, medication, regular hemodialysis and physical rehabilitation. Weaning strategy adjusted with help of electrical impedance tomography.Outcomes:The muscle power of the patient gradually recovered. Extubation of the patient was successful and he was discharged without oxygen required.Lessons:This case gives us the lesson that MMA can be newly diagnosed in adult patient. A new mut genotype sequence was discovered. The use of electrical impedance tomography to select a suitable method for inspiratory muscle training was possible and useful.

Uncommonly Missed Diagnosis of Methylmalonic Acidemia (MMA) in Adults and Usefulness of Testing for MMA in Cases of Seizures/Neuropathy/Weakness/Ataxia

“…However, apart from being diagnosed when the condition was less severe than other adults in the literature, his symptoms and disease progression are very similar to other reported cases of adults diagnosed with MMA later in life. One such example of the devastating impact of a missed diagnosis comes from a case of a 26-year-old man presenting for the first time with hypotonia and acute respiratory failure requiring intubation and mechanical ventilation [6]. The patient initially presented to the emergency department with a chief complaint of nausea, vomiting, and abdominal pain as well as progressive exertional dyspnea.…”

“…As soon as the condition was identified, he was placed on a specialized diet and his neurological condition improved substantially. Methylmalonic acid levels declined substantially in just 10 days and his muscle strength substantially increased [6]. He was rehabilitated and sent home with no deficits and was maintained on a specialized diet.…”

Pre-implantation genetic diagnosis in an Iranian family with a novel mutation in MUT gene

“…Methylmalonic acidemia (MMA) is an autosomal recessive metabolic disorder [1] that affects 1:48,000 to 1:61, 000 newborns in western population [2]. The disease usually presents with lethargy and signs of metabolic crisis including acidosis, hyperketonemia, hypo-or hyperglycaemia and hyperammonemia which may lead to multiorgan failure, coma and even death in the first year of life in affected individuals [3,4].…”