rs1557929628

Variant names:

• chr1-111776111-A-G
• rs1557929628
• NM_001378969.1:c.1934T>C

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 3P and 4B. PM2 PP2 BP4_Strong

The NM_001378969.1(KCND3):​c.1934T>C​(p.Ile645Thr) 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. 16/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: KCND3 NM_001378969.1 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.08
• Publications: 0 publications found

Genes affected

KCND3 (HGNC:6239): (potassium voltage-gated channel subfamily D member 3) 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, shal-related subfamily, members of which form voltage-activated A-type potassium ion channels and are prominent in the repolarization phase of the action potential. This member includes two isoforms with different sizes, which are encoded by alternatively spliced transcript variants of this gene. [provided by RefSeq, Jul 2008]

KCND3 Gene-Disease associations (from GenCC):

• neurodevelopmental disorder

  Inheritance: AD Classification: STRONG Submitted by: G2P
• spinocerebellar ataxia type 19/22

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Orphanet, Ambry Genetics
• Brugada syndrome 9

  Inheritance: AD Classification: LIMITED Submitted by: Genomics England PanelApp
• Brugada syndrome 1

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Likely_benign. The variant received -1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the KCND3 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 20 curated pathogenic missense variants (we use a threshold of 10). The gene has 4 curated benign missense variants. Gene score misZ: 3.8545 (above the threshold of 3.09). Trascript score misZ: 4.8782 (above the threshold of 3.09). GenCC associations: The gene is linked to spinocerebellar ataxia type 19/22, neurodevelopmental disorder, Brugada syndrome 1, Brugada syndrome 9.
• BP4: Computational evidence support a benign effect (MetaRNN=0.05717975).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCND3	NM_001378969.1	c.1934T>C	p.Ile645Thr	missense_variant	Exon 8 of 8	ENST00000302127.5	NP_001365898.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCND3	ENST00000302127.5	c.1934T>C	p.Ile645Thr	missense_variant	Exon 8 of 8	5	NM_001378969.1	ENSP00000306923.4
KCND3	ENST00000315987.6	c.1934T>C	p.Ile645Thr	missense_variant	Exon 8 of 8	1		ENSP00000319591.2
KCND3	ENST00000369697.5	c.1877T>C	p.Ile626Thr	missense_variant	Exon 6 of 6	1		ENSP00000358711.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Spinocerebellar ataxia type 19/22 Uncertain:1

Feb 15, 2018

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has not been reported in the literature in individuals with KCND3-related disease. 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. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant is not present in population databases (ExAC no frequency). This sequence change replaces isoleucine with threonine at codon 645 of the KCND3 protein (p.Ile645Thr). The isoleucine residue is weakly conserved and there is a moderate physicochemical difference between isoleucine and threonine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.062
BayesDel_addAF	Benign	-0.018	T
BayesDel_noAF	Benign	-0.26
CADD	Benign	20
DANN	Benign	0.79
DEOGEN2	Benign	0.24	.;T;.
Eigen	Benign	-0.35
Eigen_PC	Benign	-0.082
FATHMM_MKL	Benign	0.75	D
LIST_S2	Benign	0.66	.;T;T
M_CAP	Benign	0.019	T
MetaRNN	Benign	0.057	T;T;T
MetaSVM	Benign	-0.61	T
MutationAssessor	Benign	-0.69	.;N;.
PhyloP100		2.1
PrimateAI	Uncertain	0.61	T
PROVEAN	Benign	0.14	N;N;N
REVEL	Benign	0.26
Sift	Benign	0.87	T;T;T
Sift4G	Benign	0.40	T;T;T
Polyphen		0.0	.;B;.
Vest4		0.045
MutPred		0.13		.;Gain of glycosylation at I645 (P = 0.0188);.;
MVP		0.20
MPC		0.45
ClinPred		0.20	T
GERP RS		4.5
Varity_R		0.068
gMVP		0.48
Mutation Taster		=92/8	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.11		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: rs1557929628; hg19: chr1-112318733;