rs1555889171

Variant names:

• chr20-49374982-A-T
• rs1555889171
• NM_004975.4:c.578T>A

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_004975.4(KCNB1):​c.578T>A​(p.Ile193Lys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: KCNB1 NM_004975.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.97
• Publications: 0 publications found

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]

KCNB1 Gene-Disease associations (from GenCC):

• complex neurodevelopmental disorder

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• developmental and epileptic encephalopathy, 26

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• undetermined early-onset epileptic encephalopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000290421 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 8 uncertain in NM_004975.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.941

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_004975.4. 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
	KCNB1	NM_004975.4	MANE Select	c.578T>A	p.Ile193Lys	missense	Exon 2 of 2	NP_004966.1	Q14721

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNB1	ENST00000371741.6	TSL:1 MANE Select	c.578T>A	p.Ile193Lys	missense	Exon 2 of 2	ENSP00000360806.3	Q14721
	KCNB1	ENST00000635465.1	TSL:1	c.578T>A	p.Ile193Lys	missense	Exon 3 of 3	ENSP00000489193.1	Q14721
	KCNB1	ENST00000635878.1	TSL:5	c.97-75599T>A		intron	N/A	ENSP00000489908.1	A0A1B0GU02

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
-	1	-	Developmental and epileptic encephalopathy, 26 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.55
CADD	Pathogenic	32
DANN	Benign	0.96
DEOGEN2	Pathogenic	0.94	D
Eigen	Pathogenic	0.95
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.90	D
M_CAP	Pathogenic	0.51	D
MetaRNN	Pathogenic	0.94	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.5	H
PhyloP100		9.0
PrimateAI	Pathogenic	0.83	D
PROVEAN	Pathogenic	-5.8	D
REVEL	Pathogenic	0.95
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0020	D
Polyphen		1.0	D
Vest4		0.77
MutPred		0.77		Loss of stability (P = 0.0055)
MVP		0.99
MPC		4.3
ClinPred		0.99	D
GERP RS		6.0
Varity_R		0.80
gMVP		0.99
Mutation Taster		=33/67	disease causing

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: rs1555889171; hg19: chr20-47991519;