*Correspondence: mariamarianamuniz@hotmail.com.
Abstract
Case Presentation: RFR, 11 years old, presented with global retardation in neuropsychomotor developmental
milestones and a previous diagnosis of Autistic Spectrum Disorder. At 6 years of age,
he started having episodes of bilateral tonic-clonic and focal dysperceptive seizures.
He took carbamazepine, without response, with partial control with valproic acid.
One year later, he began to present dysmetria, chorea of the upper limbs and trunk
ataxia, besides findings such as ocular and retroauricular telangiectasias. Metabolic
screening and alpha-fetoprotein dosage were performed, without alterations. Magnetic
resonance imaging of the brain demonstrated hyperintensity on T2 and Flair images
involving periventricular white matter, especially near the atria of the lateral ventricles,
besides slight ectasia of the posterior horns of the lateral ventricles. Electroencephalogram
with an encephalopathy pattern and no discharges. A genetic panel was performed and
identified a variant of uncertain significance, described as NM_018896.5, in the CACNA1G
gene, associated with spinocerebellar ataxia type 42. The patient presents with a
slowly progressive evolution of cerebellar symptoms since its onset.
Discussion: Spinocerebellar ataxias (SCAs) constitute a heterogeneous group of neurodegenerative
disorders. SCA 42 is a rare subtype, with an estimated prevalence of less than 1 per
1 000 000 individuals. It has autosomal dominant inheritance and is a mutation caused
by pathogenic variant in the calcium channel 1G (CACNA1G) gene that encodes T-type
voltage-dependent calcium channels, widely expressed in the central nervous system,
playing an important role in the regulation of membrane potential and calcium-mediated
signaling pathway. Thus, mutations can impair cell behavior and cause neurodegenerative
disorders. It has great clinical and genetic variability, a slowly progressive course,
and variable age of onset and severity. It presents clinical signs such as ataxia,
dysarthria, and alterations in neuropsychomotor development, as observed in the case
described. Treatment has no proven efficacy. Early multidisciplinary therapies help
to improve quality of life.
Final Comments: Spinocerebellar ataxia type 42 is a rare subgroup of a heterogeneous group of neurodegenerative
diseases. It shows great clinical variability, and its follow-up is important. Early
diagnosis helps in genetic counseling and patient support
