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Table 2 Natural history of mt-aaRS-related leukodystrophies

From: Mitochondrial aminoacyl-tRNA synthetase disorders: an emerging group of developmental disorders of myelination

Mean age at onset (age range)8 years (5 months–40 years)6 months (birth–16 months)25 years (1.5–44 years)
Rate of disease progressionSlow, gradual >
rapid decline
Biphasic with stability or improvement after early “hit”Rapid decline within a few years
Risk of disabilityGreater disability associated with earlier age of onsetGreater disability associated with initial clinical and imaging severityHigh risk of motor and cognitive impairment
Risk of mortalityIncreased for infantile-onset disease, otherwise lowIncreased for early onset, severe disease with multi-organ involvementIncreased risk from late disease complications