NM_001378969.1:c.680_682delTCT

Variant names:

• chr1-111982044-CAGA-C
• rs397515475
• NM_001378969.1:c.680_682delTCT

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM2 PM4_Supporting PP5_Very_Strong

The NM_001378969.1(KCND3):​c.680_682delTCT​(p.Phe227del) variant causes a disruptive inframe deletion change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. F227F) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 31)
• Consequence: KCND3 NM_001378969.1 disruptive_inframe_deletion
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 9.32
• Publications: 9 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: Pathogenic. The variant received 11 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM4: Nonframeshift variant in NON repetitive region in NM_001378969.1. Strenght limited to Supporting due to length of the change: 1aa.
• PP5: Variant 1-111982044-CAGA-C is Pathogenic according to our data. Variant chr1-111982044-CAGA-C is described in ClinVar as Pathogenic. ClinVar VariationId is 66061.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCND3	NM_001378969.1	c.680_682delTCT	p.Phe227del	disruptive_inframe_deletion	Exon 2 of 8	ENST00000302127.5	NP_001365898.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCND3	ENST00000302127.5	c.680_682delTCT	p.Phe227del	disruptive_inframe_deletion	Exon 2 of 8	5	NM_001378969.1	ENSP00000306923.4

Frequencies

GnomAD3 genomes Cov.: 31

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Spinocerebellar ataxia type 19/22 Pathogenic:3

Jan 04, 2021

Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

- -

Jun 14, 2022

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: KCND3 c.680_682delTCT (p.Phe227del) results in an in-frame deletion that is predicted to remove one amino acid from the Ion transport domain (IPR005821) of the encoded protein. The variant was absent in 250304 control chromosomes. c.680_682delTCT has been reported in the literature to cosegregate with disease in multiple individuals from two independent well genotyped families affected with Spinocerebellar Ataxia Type 22, which overlaps with the locus of Spinocerebellar Ataxia Type 19 (example, Lee_2012). It has also been reported among pathogenic variants identified in at-least one individual within a cohort of individuals undergoing next-generation sequencing (NGS) analysis for Herediatry Ataxia's (example, Galatolo_2021). These data indicate that the variant is very likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function (Lee_2012). The most pronounced variant effect results in low current densities by electrophysiological recordings and intracellular retention, suggesting that p.F227del causes a loss of channel function by interfering with proper plasma membrane targeting and incorporation into a functional tetrameric channel complex. Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Dec 01, 2012

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

not provided Pathogenic:2

Jan 09, 2024

Athena Diagnostics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has been identified in multiple unrelated individuals with clinical features associated with this gene. This variant has not been reported in large, multi-ethnic general populations. (http://gnomad.broadinstitute.org) This variant segregates with disease in multiple families. Assessment of experimental evidence suggests this variant results in abnormal protein function. (PMID: 23280837, 25854634) -

Oct 23, 2020

Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		9.3
Mutation Taster		=19/81	disease causing (ClinVar)

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: rs397515475; hg19: chr1-112524666; COSMIC: COSV56184108;