chr12-4912353-G-C

Variant names:

• chr12-4912353-G-C
• rs104894353
• NM_000217.3:c.975G>C

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5

The NM_000217.3(KCNA1):​c.975G>C​(p.Glu325Asp) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. E325G) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 30)
• Consequence: KCNA1 NM_000217.3 missense
• Clinical Significance: Pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: 4.94
• Publications: 15 publications found

Genes affected

KCNA1 (HGNC:6218): (potassium voltage-gated channel subfamily A member 1) This gene encodes a voltage-gated delayed potassium channel that is phylogenetically related to the Drosophila Shaker channel. The encoded protein has six putative transmembrane segments (S1-S6), and the loop between S5 and S6 forms the pore and contains the conserved selectivity filter motif (GYGD). The functional channel is a homotetramer. The N-terminus of the channel is associated with beta subunits that can modify the inactivation properties of the channel as well as affect expression levels. The C-terminus of the channel is complexed to a PDZ domain protein that is responsible for channel targeting. Mutations in this gene have been associated with myokymia with periodic ataxia (AEMK). [provided by RefSeq, Jul 2008]

KCNA1 Gene-Disease associations (from GenCC):

• episodic ataxia type 1

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, ClinGen, Genomics England PanelApp, Orphanet
• episodic kinesigenic dyskinesia 1

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• genetic developmental and epileptic encephalopathy

  Inheritance: AD, AR Classification: SUPPORTIVE, LIMITED Submitted by: Orphanet, G2P
• isolated autosomal dominant hypomagnesemia, Glaudemans type

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000256654 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 8 uncertain in NM_000217.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr12-4912352-A-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2759454.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant in the KCNA1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 33 curated pathogenic missense variants (we use a threshold of 10). The gene has 3 curated benign missense variants. Gene score misZ: 3.3255 (above the threshold of 3.09). Trascript score misZ: 3.8671 (above the threshold of 3.09). GenCC associations: The gene is linked to isolated autosomal dominant hypomagnesemia, Glaudemans type, episodic ataxia type 1, genetic developmental and epileptic encephalopathy, episodic kinesigenic dyskinesia 1.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.953
• PP5: Variant 12-4912353-G-C is Pathogenic according to our data. Variant chr12-4912353-G-C is described in ClinVar as Pathogenic. ClinVar VariationId is 13485.Status of the report is no_assertion_criteria_provided, 0 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000217.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNA1	NM_000217.3	MANE Select	c.975G>C	p.Glu325Asp	missense	Exon 2 of 2	NP_000208.2	Q09470

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNA1	ENST00000382545.5	TSL:4 MANE Select	c.975G>C	p.Glu325Asp	missense	Exon 2 of 2	ENSP00000371985.3	Q09470
	KCNA1	ENST00000639680.1	TSL:5	c.75+87G>C		intron	N/A	ENSP00000492218.1	A0A1W2PQM4
	KCNA1	ENST00000639306.1	TSL:5	n.813G>C		non_coding_transcript_exon	Exon 1 of 2	ENSP00000492506.1	A0A1W2PRI2

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome Cov.: 43

GnomAD4 genome Cov.: 30

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: no assertion criteria provided

Pathogenic	VUS	Benign	Condition
1	-	-	Episodic ataxia type 1 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.48	D
BayesDel_noAF	Pathogenic	0.45
CADD	Uncertain	23
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D
Eigen	Uncertain	0.41
Eigen_PC	Uncertain	0.42
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.87	D
M_CAP	Pathogenic	0.37	D
MetaRNN	Pathogenic	0.95	D
MetaSVM	Pathogenic	1.2	D
MutationAssessor	Benign	1.6	L
PhyloP100		4.9
PrimateAI	Pathogenic	0.86	D
PROVEAN	Uncertain	-2.9	D
REVEL	Pathogenic	0.86
Sift	Uncertain	0.0050	D
Sift4G	Benign	0.061	T
Polyphen		0.56	P
Vest4		0.90
MutPred		0.81		Gain of catalytic residue at E325 (P = 0.0491)
MVP		0.94
MPC		2.3
ClinPred		0.96	D
GERP RS		4.2
PromoterAI		-0.0040	Neutral
Varity_R		0.77
gMVP		0.98
Mutation Taster		=23/77	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs104894353; hg19: chr12-5021519;