Mitochondrial Complex IV Deficiency (APOPT1)
Mitochondrial complex IV deficiency (APOPT1-related) is an autosomal recessive disorder caused by pathogenic variants in multiple genes, including APOPT1. The onset and severity of this condition varies from acute neurometabolic decompensation in late infancy to subtle neurological signs presenting in adolescence. Neurological deficiencies include loss of developmental milestones such as the ability to walk, sit, or speak, seizures, and spastic weakness in all extremities. Typically, the clinical course stabilizes, and marked recovery of developmental milestones has been observed. Some, but not all, individuals experience cognitive impairment. No clear genotype-phenotype correlation has been established.
For information about carrier frequency and residual risk, please see the residual risk table.