Next‐generation sequencing identifies novel CACNA1A gene mutations in episodic ataxia type 2

Abstract

Episodic Ataxia type 2 (EA2) is a rare autosomal dominantly inherited neurological disorder characterized by recurrent disabling imbalance, vertigo, and episodes of ataxia lasting minutes to hours. EA2 is caused most often by loss of function mutations of the calcium channel gene CACNA1A. In addition to EA2, mutations in CACNA1A are responsible for two other allelic disorders: familial hemiplegic migraine type 1 (FHM1) and spinocerebellar ataxia type 6 (SCA6). Herein, we have utilized next‐generation sequencing (NGS) to screen the coding sequence, exon‐intron boundaries, and Untranslated Regions (UTRs) of five genes where mutation is known to produce symptoms related to EA2, including CACNA1A. We performed this screening in a group of 31 unrelated patients with EA2 symptoms. Both novel and known mutations were detected through NGS technology, and confirmed through Sanger sequencing. Genetic testing showed in total 15 mutation bearing patients (48%), of which nine were novel mutations (6 missense and 3 small frameshift deletion mutations) and six known mutations (4 missense and 2 nonsense).These results demonstrate the efficiency of our NGS‐panel for detecting known and novel mutations for EA2 in the CACNA1A gene, also identifying a novel missense mutation in ATP1A2 which is not a normal target for EA2 screening.

Gain-of-function mutations in the UNC-2/CaV2α channel lead to hyperactivity and excitation-dominant synaptic transmission in Caenorhabditis elegans

“…Most intragenic suppressor mutations result in uncoordinated and lethargic phenotypes, indicating that they are hypomorphic alleles. Interestingly, some intragenic suppressor mutations resemble those found in CACNA1A in EA2 patients, including the C324Y mutation in the domain I S5-S6 loop (analogous to the CACNA1A(C287Y) mutation) (Wan et al, 2005), and the L1357F mutation in the domain IV S5-S6 loop analogous to CACNA1A (L1749P) mutation (Maksemous et al, 2016). These and other CACNA1A(EA2) missense mutations are partial or total loss-of-function mutations that lead to defects in channel trafficking or positive shifts in the voltage threshold for activation (Jeng et al, 2008;Mezghrani et al, 2008).…”

Targeted next generation sequencing identifies novel NOTCH3 gene mutations in CADASIL diagnostics patients

“…Comprehensive screening for NOTCH3 using the AmpliSeq Custom NGS panel [7] (Thermo Fisher Scientific, Scoresby, Victoria, Australia) for targeted gene sequencing was conducted on 44 patients, previously screened for standard sequencing exons (3 and 4) and/or (2,11, 18 and 19) by SS and classified as being negative for known mutations.…”

“…We have previously demonstrated the efficiency of our NGS panel for detecting known and novel mutations in a cohort of episodic ataxia patients and increasing the rate of mutation detection by 48 % [7]. We have now utilised this custom targeted massively parallel NGS panel to examine the coding sequences, intron/exon boundaries including 20–100 bases of flanking intronic nucleotides and the 5′ and 3′UTR regions of NOTCH3 in a cohort of 44 patients with clinically suspicious CADASIL.…”

“…With the advent of next-generation sequencing (NGS), the sequencing of target genes, regions, exomes or whole genomes, provides cost-effective, high-throughput screening suitable for molecular diagnostics enabling detection of a wide array of mutations with sensitivity and specificity. Here, we have performed targeted gene sequencing using a custom five-gene NGS panel [7], encompassing the coding sequences, 20–100 bp exon/intron boundaries and the 5′ and 3′UTR regions of NOTCH3 in 44 patients.…”

Next-generation sequencing in neuromuscular diseases: Erratum

“…Neuromuscular disorders (NMD) are a broad group of conditions that affect muscles (myopathies, dystrophies, ion channel diseases and malignant hyperthermia) (1)(2)(3)(4)(5)(6), nerves (Charcot Marie Tooth (CMT) (7,8), motor neurone disease (MND) (9)(10)(11)(12)(13) hereditary spastic paraplegia (14)(15)(16)(17)(18) and spinal muscular atrophies (19)(20)(21) and neuromuscular junctions (myasthenic syndromes) (22). Muscle weakness, wasting, fasciculation, cramps, numbness, respiratory and cranial nerve palsies are common features in several NMDs.…”