Mitochondrial encephalomyopathy with elevated methylmalonic acid is caused by SUCLA2 mutations

Area of Science:

• Genetics
• Biochemistry
• Neurology

Background:

• Autosomal recessive mitochondrial encephalomyopathy is a severe neurological disorder.
• Elevated methylmalonic acid is a key biochemical marker.
• A founder effect in the Faroe Islands leads to a high incidence of this disorder.

Purpose of the Study:

• To identify the genetic cause of autosomal recessive mitochondrial encephalomyopathy with elevated methylmalonic acid.
• To investigate the molecular mechanism underlying the observed symptoms.

Main Methods:

• Homozygosity mapping using Affymetrix 10 K array.
• Mutation analysis of the SUCLA2 gene.
• Biochemical analysis of methylmalonic acid levels.

Main Results:

• A homozygous region on chromosome 13q14 was identified, harboring the SUCLA2 gene.
• A novel splice site mutation (IVS4 + 1G --> A) in SUCLA2 was found, causing exon 4 skipping.
• Elevated methylmalonic acid levels were confirmed, consistent with impaired succinyl-CoA ligase activity.

Conclusions:

• Mutations in the SUCLA2 gene are a cause of autosomal recessive mitochondrial encephalomyopathy with elevated methylmalonic acid.
• The identified SUCLA2 mutation disrupts the ATP-forming beta subunit of succinyl-CoA ligase, leading to metabolic dysfunction.
• This study expands the known spectrum of SUCLA2-related disorders and highlights its significance in mitochondrial metabolism.