rs749309558

chr19-13334405-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PP2 PP3_Moderate

The NM_001127222.2(CACNA1A):c.1171G>A(p.Gly391Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000138 in 1,445,904 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. G391G) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: CACNA1A NM_001127222.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.75

Genes affected

CACNA1A (HGNC:1388): (calcium voltage-gated channel subunit alpha1 A) Voltage-dependent calcium channels mediate the entry of calcium ions into excitable cells, and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, and gene expression. Calcium channels are multisubunit complexes composed of alpha-1, beta, alpha-2/delta, and gamma subunits. The channel activity is directed by the pore-forming alpha-1 subunit, whereas, the others act as auxiliary subunits regulating this activity. The distinctive properties of the calcium channel types are related primarily to the expression of a variety of alpha-1 isoforms, alpha-1A, B, C, D, E, and S. This gene encodes the alpha-1A subunit, which is predominantly expressed in neuronal tissue. Mutations in this gene are associated with 2 neurologic disorders, familial hemiplegic migraine and episodic ataxia 2. This gene also exhibits polymorphic variation due to (CAG)n-repeats. Multiple transcript variants encoding different isoforms have been found for this gene. In one set of transcript variants, the (CAG)n-repeats occur in the 3' UTR, and are not associated with any disease. But in another set of variants, an insertion extends the coding region to include the (CAG)n-repeats which encode a polyglutamine tract. Expansion of the (CAG)n-repeats from the normal 4-18 to 21-33 in the coding region is associated with spinocerebellar ataxia 6. [provided by RefSeq, Jul 2016]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, CACNA1A
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.87

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CACNA1A	NM_001127222.2	c.1171G>A	p.Gly391Arg	missense_variant	8/47	ENST00000360228.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CACNA1A	ENST00000360228.11	c.1171G>A	p.Gly391Arg	missense_variant	8/47	1	NM_001127222.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000802 AC: 2 AN: 249270 Hom.: 0 AF XY: 0.00000740 AC XY: 1 AN XY: 135226

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000579

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000138 AC: 2 AN: 1445904 Hom.: 0 Cov.: 31 AF XY: 0.00000139 AC XY: 1 AN XY: 720270

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000447

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.00000827 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Episodic ataxia type 2;C4310716:Developmental and epileptic encephalopathy, 42 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Sep 15, 2023

This variant has not been reported in the literature in individuals affected with CACNA1A-related conditions. This variant is present in population databases (rs749309558, gnomAD 0.006%). This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 391 of the CACNA1A protein (p.Gly391Arg). ClinVar contains an entry for this variant (Variation ID: 426536). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt CACNA1A protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

May 04, 2023

In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; In addition, In silico analysis suggests this variant may impact gene splicing. In the absence of RNA/functional studies, the actual effect of this sequence change is unknown.; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 26666653) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.21	D
BayesDel_noAF	Pathogenic	0.24
Cadd	Pathogenic	28
Dann	Uncertain	1.0
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Pathogenic	0.98	D;D;D;D;D;D;D;D;.;D;D;D;D;D;D
M_CAP	Uncertain	0.23	D
MetaRNN	Pathogenic	0.87	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Pathogenic	0.89	D
Sift4G	Uncertain	0.019	D;D;.;.;.;.;.;.;.;.;.;D;.;.;.
Polyphen		1.0	.;D;.;.;.;.;.;.;.;.;.;.;.;.;.
Vest4		0.82
MutPred		0.49		Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);.;Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);Gain of MoRF binding (P = 0.0102);
MVP		0.93
MPC		2.5
ClinPred		0.99	D
GERP RS		5.1
Varity_R		0.54
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.12		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs749309558; hg19: chr19-13445219; COSMIC: COSV64210282;