12-32850765-C-T

Position:

• chr12-32850765-C-T

Variant summary

Our verdict is Pathogenic. Variant got 22 ACMG points: 22P and 0B. PVS1 PM2 PP3_Strong PP5_Very_Strong

The NM_001005242.3(PKP2):​c.1378+1G>A variant causes a splice donor change. The variant allele was found at a frequency of 0.00000206 in 1,457,724 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: PKP2 NM_001005242.3 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 6.33

Genes affected

PKP2 (HGNC:9024): (plakophilin 2) This gene encodes a member of the arm-repeat (armadillo) and plakophilin gene families. Plakophilin proteins contain numerous armadillo repeats, localize to cell desmosomes and nuclei, and participate in linking cadherins to intermediate filaments in the cytoskeleton. This gene may regulate the signaling activity of beta-catenin and is required to maintain transcription of genes that control intracellular calcium cycling including ryanodine receptor 2, ankyrin-B, triadin, and calcium channel, voltage-dependent, L type, alpha 1C. Mutations in this gene are associated with different inherited cardiac conditions including Arrythmogenic Cardiomyopathy, Brugada Syndrome, and Idiopathic Ventricular Fibrillation. A processed pseudogene with high similarity to this gene has been mapped to chromosome 12p13. [provided by RefSeq, May 2022]

ACMG classification

Verdict is Pathogenic. Variant got 22 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 4.9, offset of -46, new splice context is: cagGTgctg. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 12-32850765-C-T is Pathogenic according to our data. Variant chr12-32850765-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 923177.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr12-32850765-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PKP2	NM_001005242.3	c.1378+1G>A		splice_donor_variant		ENST00000340811.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PKP2	ENST00000340811.9	c.1378+1G>A		splice_donor_variant		1	NM_001005242.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000206 AC: 3 AN: 1457724 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 725404

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.0000187

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Arrhythmogenic right ventricular dysplasia 9 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 07, 2022

This variant is also known as D460fsX464. ClinVar contains an entry for this variant (Variation ID: 923177). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. Disruption of this splice site has been observed in individuals with arrhythmogenic right ventricular cardiomyopathy (ARVC) (PMID: 18662195, 20400443). This sequence change affects a donor splice site in intron 5 of the PKP2 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in PKP2 are known to be pathogenic (PMID: 15489853, 23911551). This variant is not present in population databases (gnomAD no frequency). -

Cardiomyopathy Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Color Diagnostics, LLC DBA Color Health

Dec 03, 2019

This variant causes a G>A nucleotide substitution at the +1 position of intron 5 of the PKP2 gene. Splice site prediction tools predict that this variant may have a significant impact on RNA splicing. Although functional studies have not been performed for this variant, this variant is predicted to result in an absent or non-functional protein product. This variant has not been reported in an individual affected with arrhythmogenic right ventricular cardiomyopathy (PMID: 28523642). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Loss of PKP2 function is a known mechanism of disease. Based on the available evidence, this variant is classified as Likely Pathogenic. -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Aug 27, 2023

Identified in a 14 year old patient with arrhythmogenic cardiomyopathy (ACM), who also harbored a second PKP2 variant (c.1181T>C) in trans, who underwent heart transplant and died due to heart failure at age 18; this individual's unaffected father and paternal aunt were heterozygous for the c.1378+1G>A variant in PKP2 (PMID: 30830208); Not observed at significant frequency in large population cohorts (gnomAD); Published functional studies suggest a damaging effect by dramatically reduced expression of connexin34, though the variant does not appear to alter the organization of intercalated disk proteins (PMID: 18662195); Canonical splice site variant predicted to result in a null allele in a gene for which loss of function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 31402444, 35819174, 32522011, 28523642, 18662195, 30830208) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.36
CADD	Pathogenic	34
DANN	Uncertain	0.99
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Uncertain	0.96	D
MutationTaster	Benign	1.0	D;D
GERP RS		4.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.44		Position offset: 47
DS_DL_spliceai		0.99		Position offset: 1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs397516994; hg19: chr12-33003699;