rs797045031

Positions:

• chr1-201058493-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PVS1_Moderate PM2 PP5

The NM_000069.3(CACNA1S):​c.3526-2A>G variant causes a splice acceptor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,906 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: CACNA1S NM_000069.3 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 7.99

Genes affected

CACNA1S (HGNC:1397): (calcium voltage-gated channel subunit alpha1 S) This gene encodes one of the five subunits of the slowly inactivating L-type voltage-dependent calcium channel in skeletal muscle cells. Mutations in this gene have been associated with hypokalemic periodic paralysis, thyrotoxic periodic paralysis and malignant hyperthermia susceptibility. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.01476343 fraction of the gene. Cryptic splice site detected, with MaxEntScore 4.9, offset of -36, new splice context is: agagctccttcctcccaaAGctc. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-201058493-T-C is Pathogenic according to our data. Variant chr1-201058493-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 209137.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CACNA1S	NM_000069.3	c.3526-2A>G		splice_acceptor_variant		ENST00000362061.4	NP_000060.2
CACNA1S	XM_005245478.4	c.3526-2A>G		splice_acceptor_variant			XP_005245535.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CACNA1S	ENST00000362061.4	c.3526-2A>G		splice_acceptor_variant		1	NM_000069.3	ENSP00000355192	P2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460906 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726842

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 0.0000166

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Malignant hyperthermia, susceptibility to, 5;C3714580:Hypokalemic periodic paralysis, type 1 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jun 20, 2022

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 209137). Disruption of this splice site has been observed in individual(s) with clinical features of hypokalemic periodic paralysis (PMID: 26633545). This variant is not present in population databases (gnomAD no frequency). This sequence change affects an acceptor splice site in intron 27 of the CACNA1S gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in CACNA1S are known to be pathogenic (PMID: 26247046, 28012042). -

Hypokalemic periodic paralysis, type 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Baylor Genetics

Jun 27, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.15
CADD	Pathogenic	33
DANN	Uncertain	0.99
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.77
FATHMM_MKL	Pathogenic	0.99	D
MutationTaster	Benign	1.0	D;D
GERP RS		4.0

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.92
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AL_spliceai		1.0		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs797045031; hg19: chr1-201027621;