Table 1

Clinical, laboratory and pathological characteristics of the study families

FeaturesFamily
12345678910
Muscular presentation
 Ophthalmoplegia+
 Facies myopathica
 Exercise intolerance
 Muscle weakness+++++++
 Rhabdomyolysis
 Abnormal EMGNDNDNDNDNDNDNDNDNDND
CNS presentation
 Developmental delay++++++++++
 Loss of skills+
 Stroke-like episode
 Migraine
 Seizures+++
 Myoclonus+
 Cortical blindness+
 Pyramidal signs++++++
 Extrapyramidal
 Brainstem involvement++
Multisystem disease
 Haematology++++
 Gastrointestinal tract++++
 Endocrine/growth++
 Heart+
 Kidney
 Vision++ND
 Hearing++NDND
 Neuropathy+++++++
 Recurrent/familial++++++
Metabolic/imaging studies
 Elevated lactate+++++++++
 Elevated alanine
 Urinary TCAI excretion+++ND+
 Stroke-like picture/MRIND
 Leigh syndrome/MRI+++++ND
 Elevated lactate/MRSNDNDNDNDNDNDND+NDND
Morphology
 Ragged red/blue fibresND+ND
 COX-negative fibresNDND+ND+NDND
 Reduced COX stainingNDND+ND+ND
 Scattered fibres with intense NADH or SDH activityND++++ND
 Abnormal mitochondria/EMND++ND++NDNDND
  • +, Present; −, absent, COX, cyclo-oxygenase; CNS, central nervous system; EM, electron microscopy; EMG, electromyogram; MRS, magnetic resonance spectroscopy; NADH, nicotinamide adenine dinucleotide; ND, not done; SDH, succinate dehydrogenase; TCAI, tricarboxylic acid intermediates.