Autosomal recessive spastic ataxia-optic atrophy-dysarthria syndrome

Autosomal recessive spastic ataxia-optic atrophy-dysarthria syndrome (also known as SPAX5 or spastic ataxia 5) is an extremely rare inherited neurological disorder characterized by the combination of progressive spastic paraplegia, cerebellar ataxia, optic atrophy, and dysarthria (difficulty with speech articulation). The condition is caused by biallelic mutations in the AFG3L2 gene, which encodes a mitochondrial metalloprotease involved in protein quality control within mitochondria. This gene is more commonly associated with autosomal dominant spinocerebellar ataxia type 28 (SCA28), but recessive mutations produce a more severe and distinct phenotype. The disease primarily affects the nervous system, including the cerebellum, corticospinal tracts, and optic nerves. Patients typically present in childhood or early life with progressive difficulty walking due to spasticity and cerebellar dysfunction, progressive visual impairment from optic atrophy, and slurred speech. Additional features may include dystonia, myoclonic epilepsy, and progressive external ophthalmoplegia. Brain imaging may show cerebellar atrophy. The condition reflects underlying mitochondrial dysfunction, which explains its classification under ICD-10 code E88.8 (other specified metabolic disorders). There is currently no cure or disease-modifying treatment for this syndrome. Management is supportive and symptomatic, involving physical therapy to address spasticity and mobility issues, speech therapy for dysarthria, ophthalmological monitoring for visual decline, and antiepileptic medications if seizures are present. A multidisciplinary approach involving neurologists, ophthalmologists, and rehabilitation specialists is recommended to optimize quality of life.

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