16-23636316-CAT-C

Position:

• chr16-23636316-CAT-C

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_024675.4(PALB2):​c.228_229del​(p.Ile76MetfsTer4) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000275 in 1,457,026 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: 0.0000027 (0 hom.)
• Consequence: PALB2 NM_024675.4 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 1.30

Genes affected

PALB2 (HGNC:26144): (partner and localizer of BRCA2) This gene encodes a protein that may function in tumor suppression. This protein binds to and colocalizes with the breast cancer 2 early onset protein (BRCA2) in nuclear foci and likely permits the stable intranuclear localization and accumulation of BRCA2. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 16-23636316-CAT-C is Pathogenic according to our data. Variant chr16-23636316-CAT-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 496464.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PALB2	NM_024675.4	c.228_229del	p.Ile76MetfsTer4	frameshift_variant	4/13	ENST00000261584.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PALB2	ENST00000261584.9	c.228_229del	p.Ile76MetfsTer4	frameshift_variant	4/13	1	NM_024675.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000275 AC: 4 AN: 1457026 Hom.: 0 AF XY: 0.00000276 AC XY: 2 AN XY: 724566

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: 0.00000360

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

Familial cancer of breast Pathogenic:4

Likely pathogenic, criteria provided, single submitter	clinical testing	Human Genome Sequencing Center Clinical Lab, Baylor College of Medicine	Apr 25, 2018	This c.228_229delAT (p.Ile76Metfs*4) variant in the PALB gene has not been reported previously nor observed 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.228_229delAT (p.Ile76Metfs*4) variant in the PALB gene is classified as likely pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Sep 06, 2023	This variant is considered pathogenic. This variant creates a frameshift predicted to result in premature protein truncation. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Nov 17, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jul 08, 2023	This sequence change creates a premature translational stop signal (p.Ile76Metfs*4) in the PALB2 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in PALB2 are known to be pathogenic (PMID: 17200668, 17200671, 17200672, 24136930, 25099575). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with PALB2-related conditions. ClinVar contains an entry for this variant (Variation ID: 496464). For these reasons, this variant has been classified as Pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	May 23, 2022	This variant deletes 2 nucleotides in exon 4 of the PALB2 gene, creating a frameshift and premature translation stop signal. This variant is expected to result in an absent or non-functional protein product. To our knowledge, this variant has not been reported in individuals affected with hereditary cancer in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Loss of PALB2 function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Mar 12, 2024	The c.228_229delAT pathogenic mutation, located in coding exon 4 of the PALB2 gene, results from a deletion of two nucleotides at nucleotide positions 228 to 229, causing a translational frameshift with a predicted alternate stop codon (p.I76Mfs*4). This mutation has been reported in breast cancer cohorts (Park JS et al. Cancer Res Treat, 2022 Oct;54:1099-1110; Butz H et al. Cancers (Basel), 2023 Aug;15). In addition to the clinical data presented in the literature, this alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital

Feb 06, 2024

- -

Hereditary breast ovarian cancer syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

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

Apr 01, 2023

Variant summary: PALB2 c.228_229delAT (p.Ile76MetfsX4) results in a premature termination codon, predicted to cause an absence of the protein due to nonsense mediated decay, which is commonly known mechanism for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory. The variant was absent in 245172 control chromosomes. To our knowledge, no occurrence of c.228_229delAT in individuals affected with Hereditary Breast And Ovarian Cancer Syndrome and no experimental evidence demonstrating its impact on protein function have been reported. 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/likely pathogenic. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555461870; hg19: chr16-23647637;