Spastic Ataxia 4, Autosomal Recessive

Alternative Names

  • SPAX4
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WHO-ICD-10 version:2010

Diseases of the nervous system

Systemic atrophies primarily affecting the central nervous system

OMIM Number

613672

Mode of Inheritance

Autosomal recessive

Gene Map Locus

10p11.23

Description

SPAX4 is a neurodegenerative disorder characterized by cerebellar ataxia and spastic paraparesis.  Other defining features of this condition include dysarthria and ocular anomalies such as optic atrophy and nystagmus.  Patients also exhibit delayed walking, hyperreflexia of the lower limbs, brisk jaw jerk, extensor plantar responses, poor oromandibular coordination, learning difficulties, and in some cases, emotional lability.  The disorder results in certain laboratory abnormalities such as defects in oxidative phosphorylation in fibroblasts and decreased amount and activity of mitochondrial complexes I and IV.

SPAX4 has an onset in early childhood.  The disorder is slowly progressive and most affected patients are able to maintain independent ambulation.  Treatment is mainly symptomatic and supportive.  Patients may benefit from physical therapy, speech therapy and educational aids.

Molecular Genetics

SPAX4 follows an autosomal recessive pattern of inheritance and is caused by homozygous mutations in the MTPAP gene.  This gene encodes a polymerase responsible for the synthesis of poly(A) extensions on mitochondrial mRNA transcripts and for the catabolism of histone mRNAs.  So far a 1432A-G transition in the gene, resulting in a N478D substitution, has been associated with the disorder.

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
613672.1.1United Arab EmiratesUnknownYes Global developmental delay; Development...NM_018109.3:c.1468G>THomozygousAutosomal, RecessiveAl-Shamsi et al. 2016 Has similarly affect...
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