rs371851085

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PP2PP3BS2

The NM_172107.4(KCNQ2):​c.2029C>T​(p.Arg677Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000206 in 1,603,164 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R677P) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)
Exomes 𝑓: 0.000022 ( 0 hom. )

Consequence

KCNQ2
NM_172107.4 missense

Scores

5
9
5

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 0.239

Publications

5 publications found
Variant links:
Genes affected
KCNQ2 (HGNC:6296): (potassium voltage-gated channel subfamily Q member 2) The M channel is a slowly activating and deactivating potassium channel that plays a critical role in the regulation of neuronal excitability. The M channel is formed by the association of the protein encoded by this gene and a related protein encoded by the KCNQ3 gene, both integral membrane proteins. M channel currents are inhibited by M1 muscarinic acetylcholine receptors and activated by retigabine, a novel anti-convulsant drug. Defects in this gene are a cause of benign familial neonatal convulsions type 1 (BFNC), also known as epilepsy, benign neonatal type 1 (EBN1). At least five transcript variants encoding five different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]
KCNQ2 Gene-Disease associations (from GenCC):
  • complex neurodevelopmental disorder
    Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
  • developmental and epileptic encephalopathy, 7
    Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), G2P
  • neonatal encephalopathy with non-epileptic myoclonus
    Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
  • neonatal-onset developmental and epileptic encephalopathy
    Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
  • seizures, benign familial neonatal, 1
    Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
  • seizures, benign familial neonatal, 2
    Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
  • benign familial infantile epilepsy
    Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
  • benign familial neonatal-infantile seizures
    Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
  • benign neonatal seizures
    Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
  • malignant migrating partial seizures of infancy
    Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

PP2
Missense variant in the KCNQ2 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 319 curated pathogenic missense variants (we use a threshold of 10). The gene has 78 curated benign missense variants. Gene score misZ: 4.0411 (above the threshold of 3.09). Trascript score misZ: 3.6968 (above the threshold of 3.09). GenCC associations: The gene is linked to benign familial infantile epilepsy, malignant migrating partial seizures of infancy, developmental and epileptic encephalopathy, 7, benign familial neonatal-infantile seizures, benign neonatal seizures, neonatal-onset developmental and epileptic encephalopathy, complex neurodevelopmental disorder, seizures, benign familial neonatal, 2, seizures, benign familial neonatal, 1, neonatal encephalopathy with non-epileptic myoclonus.
PP3
MetaRNN computational evidence supports a deleterious effect, 0.804
BS2
High AC in GnomAdExome4 at 32 AD gene.

Transcripts

RefSeq

Gene Transcript HGVSc HGVSp Effect Exon rank MANE Protein UniProt
KCNQ2NM_172107.4 linkc.2029C>T p.Arg677Trp missense_variant Exon 17 of 17 ENST00000359125.7 NP_742105.1 O43526-1

Ensembl

Gene Transcript HGVSc HGVSp Effect Exon rank TSL MANE Protein Appris UniProt
KCNQ2ENST00000359125.7 linkc.2029C>T p.Arg677Trp missense_variant Exon 17 of 17 1 NM_172107.4 ENSP00000352035.2 O43526-1

Frequencies

GnomAD3 genomes
AF:
0.00000657
AC:
1
AN:
152246
Hom.:
0
Cov.:
33
show subpopulations
Gnomad AFR
AF:
0.00
Gnomad AMI
AF:
0.00
Gnomad AMR
AF:
0.0000654
Gnomad ASJ
AF:
0.00
Gnomad EAS
AF:
0.00
Gnomad SAS
AF:
0.00
Gnomad FIN
AF:
0.00
Gnomad MID
AF:
0.00
Gnomad NFE
AF:
0.00
Gnomad OTH
AF:
0.00
GnomAD2 exomes
AF:
0.0000168
AC:
4
AN:
238278
AF XY:
0.0000229
show subpopulations
Gnomad AFR exome
AF:
0.00
Gnomad AMR exome
AF:
0.0000873
Gnomad ASJ exome
AF:
0.00
Gnomad EAS exome
AF:
0.00
Gnomad FIN exome
AF:
0.00
Gnomad NFE exome
AF:
0.00
Gnomad OTH exome
AF:
0.00
GnomAD4 exome
AF:
0.0000221
AC:
32
AN:
1450918
Hom.:
0
Cov.:
36
AF XY:
0.0000235
AC XY:
17
AN XY:
722124
show subpopulations
African (AFR)
AF:
0.00
AC:
0
AN:
33470
American (AMR)
AF:
0.0000895
AC:
4
AN:
44680
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
26100
East Asian (EAS)
AF:
0.00
AC:
0
AN:
39658
South Asian (SAS)
AF:
0.0000116
AC:
1
AN:
86212
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
43412
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
5762
European-Non Finnish (NFE)
AF:
0.0000243
AC:
27
AN:
1111360
Other (OTH)
AF:
0.00
AC:
0
AN:
60264
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.486
Heterozygous variant carriers
0
3
6
9
12
15
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance

Age Distribution

Exome Het
Variant carriers
0
2
4
6
8
10
<30
30-35
35-40
40-45
45-50
50-55
55-60
60-65
65-70
70-75
75-80
>80
Age
GnomAD4 genome
AF:
0.00000657
AC:
1
AN:
152246
Hom.:
0
Cov.:
33
AF XY:
0.0000134
AC XY:
1
AN XY:
74376
show subpopulations
African (AFR)
AF:
0.00
AC:
0
AN:
41478
American (AMR)
AF:
0.0000654
AC:
1
AN:
15294
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
3472
East Asian (EAS)
AF:
0.00
AC:
0
AN:
5190
South Asian (SAS)
AF:
0.00
AC:
0
AN:
4834
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
10630
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
316
European-Non Finnish (NFE)
AF:
0.00
AC:
0
AN:
68026
Other (OTH)
AF:
0.00
AC:
0
AN:
2094
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.525
Heterozygous variant carriers
0
0
1
1
2
2
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance
Alfa
AF:
0.0000305
Hom.:
0
Bravo
AF:
0.00000378
ESP6500AA
AF:
0.00
AC:
0
ESP6500EA
AF:
0.000117
AC:
1
ExAC
AF:
0.0000248
AC:
3
EpiCase
AF:
0.00
EpiControl
AF:
0.0000593

ClinVar

Significance: Uncertain significance
Submissions summary: Uncertain:1
Revision: criteria provided, single submitter
LINK: link

Submissions by phenotype

Developmental and epileptic encephalopathy Uncertain:1
Jul 23, 2024
Labcorp Genetics (formerly Invitae), Labcorp
Significance:Uncertain significance
Review Status:criteria provided, single submitter
Collection Method:clinical testing

This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 677 of the KCNQ2 protein (p.Arg677Trp). This variant is present in population databases (rs371851085, gnomAD 0.01%). This missense change has been observed in individuals with clinical features of KCNQ2-related conditions (Invitae). ClinVar contains an entry for this variant (Variation ID: 582756). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name
Calibrated prediction
Score
Prediction
AlphaMissense
Benign
0.18
BayesDel_addAF
Uncertain
0.070
D
BayesDel_noAF
Uncertain
0.060
CADD
Uncertain
24
DANN
Uncertain
1.0
DEOGEN2
Benign
0.39
.;T;T;T;T;D;T;.;.
Eigen
Benign
-0.066
Eigen_PC
Benign
-0.089
FATHMM_MKL
Uncertain
0.86
D
LIST_S2
Pathogenic
0.99
D;D;D;D;D;D;D;D;D
M_CAP
Pathogenic
0.92
D
MetaRNN
Pathogenic
0.80
D;D;D;D;D;D;D;D;D
MetaSVM
Pathogenic
1.1
D
MutationAssessor
Uncertain
2.1
.;.;.;.;.;M;.;.;.
PhyloP100
0.24
PrimateAI
Uncertain
0.53
T
PROVEAN
Uncertain
-4.1
.;.;.;D;.;D;.;D;.
REVEL
Pathogenic
0.66
Sift
Uncertain
0.0010
.;.;.;D;.;D;.;D;.
Sift4G
Uncertain
0.016
D;D;D;D;.;D;D;D;D
Polyphen
1.0
D;.;.;.;.;D;.;D;D
Vest4
0.43
MVP
0.89
MPC
1.5
ClinPred
0.86
D
GERP RS
4.1
Varity_R
0.27
gMVP
0.41
Mutation Taster
=89/11
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

Publications

Other links and lift over

dbSNP: rs371851085; hg19: chr20-62038587; COSMIC: COSV60547015; COSMIC: COSV60547015; API