NM_000218.3:c.1795-3C>T

Variant names:

• chr11-2847764-C-T
• rs1245995530
• NM_000218.3:c.1795-3C>T

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM2 BP4_Moderate BP6

The NM_000218.3(KCNQ1):​c.1795-3C>T variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000141 in 1,420,642 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: KCNQ1 NM_000218.3 splice_region, intron
• Scores: Splicing: ADA: 0.009419
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: 1.16
• Publications: 0 publications found

Genes affected

KCNQ1 (HGNC:6294): (potassium voltage-gated channel subfamily Q member 1) This gene encodes a voltage-gated potassium channel required for repolarization phase of the cardiac action potential. This protein can form heteromultimers with two other potassium channel proteins, KCNE1 and KCNE3. Mutations in this gene are associated with hereditary long QT syndrome 1 (also known as Romano-Ward syndrome), Jervell and Lange-Nielsen syndrome, and familial atrial fibrillation. This gene exhibits tissue-specific imprinting, with preferential expression from the maternal allele in some tissues, and biallelic expression in others. This gene is located in a region of chromosome 11 amongst other imprinted genes that are associated with Beckwith-Wiedemann syndrome (BWS), and itself has been shown to be disrupted by chromosomal rearrangements in patients with BWS. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Aug 2011]

KCNQ1-AS1 (HGNC:42790): (KCNQ1 antisense RNA 1)

ACMG classification

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

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.46).
• BP6: Variant 11-2847764-C-T is Benign according to our data. Variant chr11-2847764-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 2772134.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=1, Likely_benign=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNQ1	NM_000218.3	c.1795-3C>T		splice_region_variant, intron_variant	Intron 15 of 15	ENST00000155840.12	NP_000209.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNQ1	ENST00000155840.12	c.1795-3C>T		splice_region_variant, intron_variant	Intron 15 of 15	1	NM_000218.3	ENSP00000155840.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00 AC: 0 AN: 184966 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

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: 0.00000141 AC: 2 AN: 1420642 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 702986

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 32718

American (AMR) AF: 0.00 AC: 0 AN: 39174

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25428

East Asian (EAS) AF: 0.00 AC: 0 AN: 37644

South Asian (SAS) AF: 0.00 AC: 0 AN: 80960

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 49516

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5708

European-Non Finnish (NFE) AF: 0.00000183 AC: 2 AN: 1090606

Other (OTH) AF: 0.00 AC: 0 AN: 58888

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.044843), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Long QT syndrome Uncertain:1

Apr 25, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change falls in intron 15 of the KCNQ1 gene. It does not directly change the encoded amino acid sequence of the KCNQ1 protein. It affects a nucleotide within the consensus splice site. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with KCNQ1-related conditions. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant is not likely to affect RNA splicing. 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. -

Cardiac arrhythmia Benign:1

Nov 18, 2024

Color Diagnostics, LLC DBA Color Health

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.46
CADD	Benign	12
DANN	Benign	0.77
PhyloP100		1.2

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.0094
dbscSNV1_RF	Benign	0.24
SpliceAI score (max)		0.010		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: rs1245995530; hg19: chr11-2868994;