Mitochondrial complex II deficiency:
Defects involving the flavoprotein-encoding SDHAgene are the most commonly reported cause of isolated complex II deficiency and manifest with a highly variable phenotype, which may include:
• Dialatative/hypertrophic cardiomyopathy
• Optic atrophy/ophthalmoplegia
• Leigh syndrome
• Ataxia
• Leukoencephalopathy
• Lactic acidosis
• Seizures
• Cognitive impairment
• Muscle weakness
• Exercise intolerance
Tumorigenesis:
SDHAacts also as a tumour suppressor gene. Heterozygous pathogenic variants in SDHApredispose to tumorigenesis and carriers have an increased risk of developing:
• Paraganglioma
• Phaeochromocytoma
• Gastrointestinal stromal tumour
SDHA