Dados do Trabalho

Título

SCA 5: A DIFFERENTIAL DIAGNOSIS OF ATAXIC CEREBRAL PALSY

Apresentação do caso

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).

Discussão

The spinocerebellar ataxias (SCAs) are genetic disorders characterized by incoordination, cerebellar ataxia, dysarthria, and swallowing difficulties. SCA5 is a rare subtype of SCA caused by heterozygous variants in the Spectrin beta nonerythrocytic 2 (SPTBN2) gene, and it usually affects adults. It has been recently reported in children in Europe, North America, China, and Brazil.

Comentários finais

SCA5 is a relevant clinical and genetic entity for neurologists, pediatric neurologists, pediatricians, and geneticists, particularly considering the differential diagnosis of ataxic cerebral palsy and the autosomal recessive cerebellar ataxias.

Referências (se houver)

[1] Dick KA, Ikeda Y, Day JW, Ranum LPW. Spinocerebellar ataxia type 5. Handb Clin Neurol 2012;103:451–459.
[2] Romaniello R, Citterio A, Panzeri E, et al. Novel SPTBN2 gene mutation and first intragenic deletion in early onset spinocerebellar ataxia type 5. Ann Clin Transl Neurol 2021; 8:956–963.
[3] Accogli A, St-Onge J, Addour-Boudrahem N, et al. Heterozygous missense pathogenic variants within the second spectrin repeat of SPTBN2 lead to infantile-onset cerebellar ataxia. J Child Neurol 2020;35:106–110.
[4] Bian X, Wang S, Jin S, et al. Two novel missense variants in SPTBN2 likely associated with spinocerebellar ataxia type 5. Neurol Sci 2021;1–9.

Declaração de conflito de interesses de TODOS os autores

None declared.