chr20-49372999-C-A

Variant names:

• chr20-49372999-C-A
• rs764648709
• NM_004975.4:c.2561G>T

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 3P and 2B. PM2 PP2 BP4_Moderate

The NM_004975.4(KCNB1):​c.2561G>T​(p.Arg854Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: not found (cov: 32)
• Consequence: KCNB1 NM_004975.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.787

Genes affected

KCNB1 (HGNC:6231): (potassium voltage-gated channel subfamily B member 1) Voltage-gated potassium (Kv) channels represent the most complex class of voltage-gated ion channels from both functional and structural standpoints. Their diverse functions include regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and cell volume. Four sequence-related potassium channel genes - shaker, shaw, shab, and shal - have been identified in Drosophila, and each has been shown to have human homolog(s). This gene encodes a member of the potassium channel, voltage-gated, shab-related subfamily. This member is a delayed rectifier potassium channel and its activity is modulated by some other family members. [provided by RefSeq, Jul 2008]

ENSG00000290421 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the KCNB1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 76 curated pathogenic missense variants (we use a threshold of 10). The gene has 110 curated benign missense variants. Gene score misZ: 4.269 (above the threshold of 3.09). Trascript score misZ: 5.3923 (above the threshold of 3.09). GenCC associations: The gene is linked to undetermined early-onset epileptic encephalopathy, complex neurodevelopmental disorder, developmental and epileptic encephalopathy, 26.
• BP4: Computational evidence support a benign effect (MetaRNN=0.11758509).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNB1	NM_004975.4	c.2561G>T	p.Arg854Leu	missense_variant	Exon 2 of 2	ENST00000371741.6	NP_004966.1
KCNB1	XM_011528799.3	c.2561G>T	p.Arg854Leu	missense_variant	Exon 3 of 3		XP_011527101.1
LOC105372649	XR_001754659.2	n.1201+40975C>A		intron_variant	Intron 2 of 3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNB1	ENST00000371741.6	c.2561G>T	p.Arg854Leu	missense_variant	Exon 2 of 2	1	NM_004975.4	ENSP00000360806.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.10
BayesDel_addAF	Uncertain	0.10	D
BayesDel_noAF	Benign	-0.090
CADD	Benign	12
DANN	Uncertain	0.99
DEOGEN2	Benign	0.33	T;T
Eigen	Benign	-0.64
Eigen_PC	Benign	-0.62
FATHMM_MKL	Benign	0.28	N
LIST_S2	Benign	0.77	.;T
M_CAP	Uncertain	0.13	D
MetaRNN	Benign	0.12	T;T
MetaSVM	Uncertain	0.26	D
MutationAssessor	Benign	0.34	N;N
PrimateAI	Benign	0.30	T
PROVEAN	Benign	-0.88	N;.
REVEL	Uncertain	0.33
Sift	Benign	0.048	D;.
Sift4G	Benign	0.37	T;T
Polyphen		0.26	B;B
Vest4		0.25
MutPred		0.26		Loss of phosphorylation at S857 (P = 0.0468);Loss of phosphorylation at S857 (P = 0.0468);
MVP		0.66
MPC		0.24
ClinPred		0.12	T
GERP RS		1.9
Varity_R		0.064
gMVP		0.42

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

Publications

LitVar

Other links and lift over

dbSNP: rs764648709; hg19: chr20-47989536;