chr12-32822616-C-CA

Position:

• chr12-32822616-C-CA

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PVS1 PP5_Very_Strong

The NM_001005242.3(PKP2):​c.1689_1690insT​(p.Val564CysfsTer6) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000684 in 1,461,798 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000068 (0 hom.)
• Consequence: PKP2 NM_001005242.3 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 1.59

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 16 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PP5: Variant 12-32822616-C-CA is Pathogenic according to our data. Variant chr12-32822616-C-CA is described in ClinVar as [Likely_pathogenic]. Clinvar id is 45047.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
PKP2	NM_001005242.3	c.1689_1690insT	p.Val564CysfsTer6	frameshift_variant	8/13	ENST00000340811.9	NP_001005242.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PKP2	ENST00000340811.9	c.1689_1690insT	p.Val564CysfsTer6	frameshift_variant	8/13	1	NM_001005242.3	ENSP00000342800	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251212 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135766

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000881

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000684 AC: 10 AN: 1461798 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 727200

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: 0.00

Gnomad4 NFE exome AF: 0.00000899

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Arrhythmogenic right ventricular dysplasia 9 Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 03, 2021	For these reasons, this variant has been classified as Pathogenic. Loss-of-function variants in PKP2 are known to be pathogenic (PMID: 15489853, 23911551). This variant has been reported in individuals affected with arrhythmogenic right ventricular cardiomyopathy (PMID: 28588093, Invitae). ClinVar contains an entry for this variant (Variation ID: 45047). This variant is present in population databases (rs397517010, ExAC 0.001%). This sequence change creates a premature translational stop signal (p.Val608Cysfs*6) in the PKP2 gene. It is expected to result in an absent or disrupted protein product. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Human Genome Sequencing Center Clinical Lab, Baylor College of Medicine	Apr 25, 2018	This c.1821_1822insT (p.Val608Cysfs*6) variant in the PKP2 gene has not been reported previously while observed with extremely low allele frequency in general population according to gnomad database. This variant is predicted to cause loss of function of normal protein through mRNA decay or producing a truncated protein, which is a known disease mechanism for this gene. Based on current evidences, this c.1821_1822insT (p.Val608Cysfs*6) variant in the PKP2 gene is classified as likely pathogenic. -

Arrhythmogenic right ventricular cardiomyopathy Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Molecular Genetics, Royal Melbourne Hospital	Mar 01, 2024	This sequence change in PKP2 is a frameshift variant predicted to cause a premature stop codon, p.(Val564Cysfs*6), in biologically relevant exon 8/14 leading to nonsense-mediated decay in a gene in which loss of function is an established disease mechanism. The highest population minor allele frequency in the population database gnomAD v4.0 is 0.0009% (10/1,111,944 alleles) in the European (non-Finnish) population. This variant has been reported in at least four unrelated probands with a clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy and segregates with disease in at least two families (PMID: 31319917, 28588093, 34469894). Based on the classification scheme RMH Modified ACMG/AMP Guidelines v1.6.1, this variant is classified as PATHOGENIC. Following criteria are met: PVS1, PM2_Supporting, PP1, PS4_Supporting -
Likely pathogenic, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Feb 20, 2018	The p.Val608fs variant in PKP2 has been reported in 2 individuals with clinical features of ARVC (Bhonsale 2013, LMM unpublished data). This variant has been id entified in 1/111470 of European chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP rs397517010) and has been previ ously reported in ClinVar (Variation ID 45047). This variant is predicted to cau se a frameshift, which alters the protein?s amino acid sequence beginning at pos ition 608 and leads to a premature termination codon 6 amino acids downstream. T his alteration is then predicted to lead to a truncated or absent protein. Heter ozygous loss of function of the PKP2 gene is an established disease mechanism in ARVC. In summary, although additional studies are required to fully establish i ts clinical significance, the p.Val608fs variant is likely pathogenic. ACMG/AMP Criteria applied: PVS1; PM2; PS4_S (Richards 2015). -

Cardiomyopathy Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Mar 14, 2019

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Sep 22, 2022

Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 25616645, 34120153, 23671136, 26314686, 25820315, 28588093, 31402444, 31447099, 31386562, 35536239, 31319917) -

Cardiovascular phenotype Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 02, 2016

The c.1821dupT pathogenic mutation, located in coding exon 9 of the PKP2 gene, results from a duplication of T at nucleotide position 1821, causing a translational frameshift with a predicted alternate stop codon (p.V608Cfs*6). This alteration has been reported in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) (Bhonsale A et al. Circ Arrhythm Electrophysiol. 2013;6(3):569-78; Bhonsale A et al. Eur Heart J. 2015;36(14):847-55; Groeneweg JA et al. Circ Cardiovasc Genet. 2015;8(3):437-46; te Riele AS et al. JACC: Clinical Electrophysiology. 2015;1(6):551-60). In addition to the clinical data presented in the literature, since frameshifts are typically deleterious in nature, this alteration is interpreted as a disease-causing mutation (ACMG Recommendations for Standards for Interpretation and Reporting of Sequence Variations. Revision 2007. Genet Med. 2008;10:294). -

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 31, 2022

Variant summary: PKP2 c.1821dupT (p.Val608CysfsX6) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory. The variant allele was found at a frequency of 4e-06 in 251212 control chromosomes. c.1821dupT has been reported in the literature in individuals affected with Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (example, Bhonsale_2013, te Riele_2016, DeWitt_2020). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Six 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/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
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

Publications

LitVar

Other links and lift over

dbSNP: rs397517010; hg19: chr12-32975550;