Spinocerebellar ataxia type 28 in a Chinese pedigree: A case report and literature review

Incidence of different pressure patterns of spinal cerebellar ataxia and analysis of imaging and genetic diagnosis

Neurologists have a difficult time identifying sporadic cerebellar ataxia. Multiple system atrophy of the cerebellar type (MSA-C), spontaneous late cortical cerebellar atrophy, and prolonged alcohol use are a few possible causes. In a group of people with sporadic cerebellar ataxia that was not MSA-C, an autosomal-dominant spinocerebellar ataxia (SCA) mutation was recently discovered. Chinese single-hospital cohort will be used in this study to genetic screen for SCA-related genes. One hundred forty individuals with CA were monitored over 8 years. Thirty-one individuals had familial CA, 109 patients had sporadic CA, 73 had MSA-C, and 36 had non-MSA-C sporadic CA. In 28 of the 31 non-MSA-C sporadic patients who requested the test, we carried out gene analysis, including SCA1, SCA2, SCA3, SCA6, SCA7, SCA8, SCA12, SCA17, SCA31, and dentatorubro-pallidoluysian atrophy (DRPLA). The control group consisted of family members of the patients. In 57% of the instances with spontaneous CA that were not MSA-C, gene abnormalities were discovered. The most frequent exception among individuals with sporadic CA was SCA6 (36%), followed by monsters in SCA1, 2, 3, 8, and DRPLA. In contrast, 75% of the patients with familial CA had gene abnormalities, the most frequent of which was SCA6 abnormality. The age of 69 vs 59 was higher, and the CAG repeat length was a minor age of 23 vs 25 in the former instances compared to the last one among individuals with SCA6 anomalies that were sporadic as opposed to familial cases. In sporadic CA, autosomal-dominant mutations in SCA genes, notably in SCA6, are common. Although the cause of the increased incidence of SCA6 mutations is unknown, it may be related to a greater age of onset and varied penetrance of SCA6 mutations.

Novel compound heterozygous mutations in the AFG3L2 gene in a Chinese child with microcephaly, early-onset seizures, and cerebral atrophy

Background

The most common disease caused by biallelic AFG3L2 mutations is spastic ataxia type 5 (SPAX5). Identification of complex phenotypes resulting from biallelic AFG3L2 mutations has been increasing in recent years.

Methods

A retrospective analysis was performed on a child with microcephaly and recurrent seizures. The child underwent physical and neurological examinations, laboratory tests, electroencephalography (EEG), and brain magnetic resonance imaging (MRI). Trio-whole-exome sequencing (trio-WES) was performed to identify possible causative mutations.

Results

We described a child who exhibited early-onset and intractable epilepsy, developmental regression, microcephaly, and premature death. Neuroimaging revealed global cerebral atrophy (GCA) involving the cerebrum, cerebellum, corpus callosum, brainstem, cerebellar vermis, and basal ganglia. On trio-WES, two novel compound heterozygous mutations, c.1834G > T (p.E612*) and c.2176-6T > A in the AFG3L2 gene, were identified in this patient.

Conclusions

Our findings have expanded the mutation spectrum of the AFG3L2 gene and identified a severe neurodegenerative phenotype of global cerebral atrophy caused by biallelic AFG3L2 mutations.