SCA 5: a Differential Diagnosis of Ataxic Cerebral Palsy

Case presentation: A 2.5-year-old girl presented to the Outpatient Neurogenetic Clinics of tertiary reference center, with motor delay since birth. At 2.5 years, she does not crawl, stands or walk. Perinatal history was unremarkable, there was no history of consanguinity, neither family history of neurological diseases. Neurological exam showed a cognitive and speech delay. Her speech was dysarthric. Cranial nerves were intact with normal extraocular movements and without nystagmus. Muscle tone was globally reduced and ankle joints had limited range of movement. Muscle strength was normal. Deep tendon reflexes were globally attenuated. She presented with predominant axial ataxia and mild appendicular ataxia. She was able to stand with the support of knee-ankle-foot orthoses. Electromyography and nerve conduction were normal. Brain MRI showed reduced volume of the cerebellar vermis and hemispheres associated with mild prominence of the inferior olive nucleus. Standard laboratory tests were normal. Whole exome sequencing (WES) showed a de novo heterozygous likely-pathogenic missense variant in SPTBN2 (NM_006946.3: c.1052G>C, p.Arg351Pro), previously associated with Spinocerebellar ataxia type 5 (SCA5).