Clinical features and CACNA1A gene mutation in a family with episodic ataxia type 2 / 中南大学学报(医学版)

Episodic ataxia (EA) is a group of disorders characterized by recurrent spells of vertigo, truncal ataxia, and dysarthria. Episodic ataxia type 2 (EA2), the most common subtype of EA, is an autosomal dominant disease caused by mutation of the CACNA1A gene. EA2 has been rarely reported in the Chinese population. Here we present an EA2 family admitted to Xiangya Hospital in October 2018. The proband was a 22-year-old male who complained of recurrent spells of vertigo, slurred speech, and incoordination for 4 years. Brain magnetic resonance imaging (MRI) showed cerebellar atrophy. He had neuropsychological development disorder in childhood, and cognitive assessment in adulthood showed cognitive impairment. The proband's mother and grandmother had a similar history. Peripheral blood samples from the proband and family members were collected, and genomic DNA was isolated. Whole exome sequencing of the proband detected a heterozygous frameshift mutation c.2042_2043del (p.Q681Rfs*100) of CACNA1A gene. This mutation was verified in the proband and 2 family members using Sanger sequencing. One family member carrying this mutation was free of symptoms and signs, suggesting an incomplete penetrance of the mutation. We reported a variant c.2042_2043del of CACNA1A gene as the pathogenic mutation in a Chinese EA2 family for the first time. This case enriched the clinical spectrum of CACNA1A related EA2, and contributed to the understanding of clinical and genetic characteristics of EA2 to reduce misdiagnosis.

Episodic Ataxia Type 2 due to a Deletion Mutation in the CACNA1A Gene in a Korean Family

Episodic ataxia type 2 (EA-2) is an inherited disorder that is characterized by intermittent vertigo, ataxia, and interictal gaze-evoked nystagmus. Although abnormalities associated with this disorder have been found in the CACNA1A gene encoding the alpha1A (Cav2.1) subunit of the P/Q-type calcium channel, there are few reports of genetically confirmed EA-2 in Korea. In 1998, a Korean family with acetazolamide-responsive hereditary paroxysmal ataxia was reported, but the genetic background was not defined at that time. In the present study we performed direct sequencing of the entire exons and their flanking intronic sequences of the CACNA1A gene and found a deletion mutation (c.2042_2043delAG).