20-49373288-C-T

Variant names:

• chr20-49373288-C-T
• rs774577428
• NM_004975.4:c.2272G>A

Variant summary

Our verdict is Benign. The variant received -8 ACMG points: 0P and 8B. BP4_Moderate BP6_Moderate BS2

The NM_004975.4(KCNB1):​c.2272G>A​(p.Ala758Thr) variant causes a missense change. The variant allele was found at a frequency of 0.00000752 in 1,461,888 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Benign (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A758S) has been classified as Benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000075 (0 hom.)
• Consequence: KCNB1 NM_004975.4 missense
• Clinical Significance: Benign criteria provided, single submitter B:1
• Conservation: PhyloP100: 5.80
• Publications: 1 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: Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae)
• undetermined early-onset epileptic encephalopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000290421 (HGNC:):

ACMG classification

Our verdict: Benign. The variant received -8 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.14093548).
• BP6: Variant 20-49373288-C-T is Benign according to our data. Variant chr20-49373288-C-T is described in ClinVar as Benign. ClinVar VariationId is 567109.Status of the report is criteria_provided_single_submitter, 1 stars.
• BS2: High AC in GnomAdExome4 at 11 AD gene.

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.2272G>A	p.Ala758Thr	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.2272G>A	p.Ala758Thr	missense	Exon 2 of 2	ENSP00000360806.3	Q14721
	KCNB1	ENST00000635465.1	TSL:1	c.2272G>A	p.Ala758Thr	missense	Exon 3 of 3	ENSP00000489193.1	Q14721
	KCNB1	ENST00000635878.1	TSL:5	c.97-73905G>A		intron	N/A	ENSP00000489908.1	A0A1B0GU02

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000119 AC: 3 AN: 251358 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000752 AC: 11 AN: 1461888 Hom.: 0 Cov.: 32 AF XY: 0.00000688 AC XY: 5 AN XY: 727246

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000224 AC: 1 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39700

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00000719 AC: 8 AN: 1112008

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

ClinVar submissions as Germline

Significance: Benign

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	Benign	0.15
BayesDel_addAF	Benign	-0.071	T
BayesDel_noAF	Benign	-0.17
CADD	Benign	21
DANN	Benign	0.88
DEOGEN2	Benign	0.29	T
Eigen	Benign	-0.23
Eigen_PC	Benign	-0.018
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Benign	0.78	T
M_CAP	Benign	0.077	D
MetaRNN	Benign	0.14	T
MetaSVM	Uncertain	0.062	D
MutationAssessor	Benign	1.8	L
PhyloP100		5.8
PrimateAI	Benign	0.47	T
PROVEAN	Benign	-0.72	N
REVEL	Benign	0.22
Sift	Benign	0.70	T
Sift4G	Benign	0.50	T
Polyphen		0.0020	B
Vest4		0.061
MutPred		0.24		Loss of stability (P = 0.0511)
MVP		0.51
MPC		0.18
ClinPred		0.15	T
GERP RS		4.8
Varity_R		0.054
gMVP		0.56
Mutation Taster		=56/44	polymorphism

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: rs774577428; hg19: chr20-47989825; COSMIC: COSV100870436; COSMIC: COSV100870436;