chr12-32878545-T-A

Position:

• chr12-32878545-T-A

Variant summary

Our verdict is Pathogenic. Variant got 20 ACMG points: 20P and 0B. PVS1 PP3_Strong PP5_Very_Strong

The NM_001005242.3(PKP2):​c.337-2A>T variant causes a splice acceptor change. The variant allele was found at a frequency of 0.0000137 in 1,457,808 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: 0.000014 (0 hom.)
• Consequence: PKP2 NM_001005242.3 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 4.55

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 20 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• 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 12-32878545-T-A is Pathogenic according to our data. Variant chr12-32878545-T-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 188654.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr12-32878545-T-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PKP2	NM_001005242.3	c.337-2A>T		splice_acceptor_variant		ENST00000340811.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PKP2	ENST00000340811.9	c.337-2A>T		splice_acceptor_variant		1	NM_001005242.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.0000137 AC: 20 AN: 1457808 Hom.: 0 Cov.: 32 AF XY: 0.0000110 AC XY: 8 AN XY: 725060

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: 0.0000117

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000162

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

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

Jan 03, 2024

This sequence change affects an acceptor splice site in intron 2 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). Disruption of this splice site has been observed in individuals with arrhythmogenic right ventricular cardiomyopathy (PMID: 23671136, 27532257; Invitae). ClinVar contains an entry for this variant (Variation ID: 188654). 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. -

Arrhythmogenic right ventricular cardiomyopathy Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Jan 31, 2019

The c.337-2A>T variant in PKP2 has been reported in 3 individual with ARVD/C (Bhonsale 2013, Walsh 2017) and was absent from large population studies. This variant has also been reported in ClinVar (Variation ID 188654). This variant occurs in the invariant region (+/- 1,2) of the splice consensus sequence and is predicted to cause altered splicing leading to an abnormal or absent protein. Heterozygous loss of function of the PKP2 gene is an established disease mechanism in individuals with arrhythmogenic right ventricular cardiomyopathy. In summary, although additional studies are required to fully establish its clinical significance, the c.337-2A>T variant is likely pathogenic. ACMG/AMP Criteria applied: PVS1_Strong, PM2, PS4_Supporting -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Oct 05, 2022

Not observed at significant frequency in large population cohorts (gnomAD); Canonical splice site variant in a gene for which loss-of-function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 31775751, 32372669, 23871885, 27532257, 23671136, 32123317, 31402444, 31386562, 33087929, 25820315) -

Cardiovascular phenotype Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 09, 2023

The c.337-2A>T intronic pathogenic mutation results from an A to T substitution two nucleotides upstream from coding exon 3 in the PKP2 gene. This alteration has been previously reported in an arrhythmogenic right ventricular cardiomyopathy (ARVC) cohort (Bhonsale A, Circ Arrhythm Electrophysiol 2013 Jun; 6(3):569-78). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice acceptor site and will result in the creation or strengthening of a novel splice acceptor site. In addition to the clinical data presented in the literature, alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as a disease-causing mutation. -

Familial isolated arrhythmogenic right ventricular dysplasia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

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

May 13, 2024

Variant summary: PKP2 c.337-2A>T is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: Four predict the variant abolishes a 3' acceptor site. However, these predictions have yet to be confirmed by functional studies. The frequency data for this variant in gnomAD is considered unreliable, as metrics indicate poor data quality at this position. c.337-2A>T has been reported in the literature in individuals affected with Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy. These data indicate that the variant is likely to be associated with disease. The following publications have been ascertained in the context of this evaluation (PMID: 31386562, 23671136, 26314686). ClinVar contains an entry for this variant (Variation ID: 188654). Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	-0.050
CADD	Pathogenic	33
DANN	Uncertain	0.98
Eigen	Pathogenic	0.77
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Uncertain	0.96	D
MutationTaster	Benign	1.0	D;D
GERP RS		4.9

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.86
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.82		Position offset: -27
DS_AL_spliceai		0.99		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs786204389; hg19: chr12-33031479;