rs774949203

Positions:

• chr16-23637964-A-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3 PP5

The NM_024675.4(PALB2):​c.109-12T>A variant causes a splice polypyrimidine tract, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 32)
• Consequence: PALB2 NM_024675.4 splice_polypyrimidine_tract, intron
• Scores: Splicing: ADA: 0.9996
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:6 U:1
• Conservation: PhyloP100: 5.16

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 Uncertain_significance. Variant got 4 ACMG points.

• 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 16-23637964-A-T is Pathogenic according to our data. Variant chr16-23637964-A-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 490064.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=4, Pathogenic=1, Uncertain_significance=1}. Variant chr16-23637964-A-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PALB2	NM_024675.4	c.109-12T>A		splice_polypyrimidine_tract_variant, intron_variant		ENST00000261584.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PALB2	ENST00000261584.9	c.109-12T>A		splice_polypyrimidine_tract_variant, intron_variant		1	NM_024675.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251448 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135902

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: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:6 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Jul 10, 2020	Non-canonical splice site variant demonstrated to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease (Kraus 2017); Observed in individuals with personal and/or family history of breast cancer (Hellebrand 2011, Kraus 2017); Not observed at a significant frequency in large population cohorts (Lek 2016); In silico analysis, which includes splice predictors and evolutionary conservation, supports a deleterious effect; This variant is associated with the following publications: (PMID: 27616075, 21618343) -
Likely pathogenic, no assertion criteria provided	curation	Leiden Open Variation Database	Dec 04, 2019	Curators: Marc Tischkowitz, Arleen D. Auerbach. Submitter to LOVD: Andreas Laner. -

Familial cancer of breast Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 13, 2024	This sequence change falls in intron 2 of the PALB2 gene. It does not directly change the encoded amino acid sequence of the PALB2 protein. RNA analysis indicates that this variant induces altered splicing and may result in an absent or disrupted protein product. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with a personal or family history of breast cancer (PMID: 21618343, 27616075). ClinVar contains an entry for this variant (Variation ID: 490064). Studies have shown that this variant results in activation of a cryptic splice site and introduces a premature termination codon (PMID: 21618343; Invitae). The resulting mRNA is expected to undergo nonsense-mediated decay. For these reasons, this variant has been classified as Pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Nov 23, 2022	- -

Hereditary cancer-predisposing syndrome Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Jan 25, 2022	This variant causes a T to A nucleotide substitution at the -12 position of intron 2 of the PALB2 gene. An RNA study has shown that this variant creates a cryptic splice acceptor site in intron 2, resulting in the retention of intronic sequence (c.108_109insTCTCCTCTAG) and a frameshift in the open reading frame (PMID: 27616075). This variant has been reported in at least five individuals affected with breast cancer (PMID: 21618343, 27616075; Communication with external laboratories and the German Breast Cancer Consortium). These individuals were presented with familial, early-onset, bilateral, or triple-negative breast cancer. This variant has been identified in 1/251448 chromosomes in the general population by the Genome Aggregation Database (gnomAD). Based on the available evidence, this variant is classified as Likely Pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Aug 14, 2023	The c.109-12T>A intronic variant results from a T to A substitution 12 nucleotides upstream from coding exon 3 in the PALB2 gene. This alteration was detected in an individual diagnosed with breast cancer and RT-PCR showed an insertion of 10 base pairs resulting in a frameshift protein (Kraus C et al. Int J Cancer, 2017 Jan;140:95-102). 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. RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Fanconi anemia complementation group N Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Revvity Omics, Revvity

Jul 22, 2021

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.38
CADD	Benign	21
DANN	Benign	0.67

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.74		Position offset: -2
DS_AL_spliceai		0.98		Position offset: -12

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

Publications

LitVar

Other links and lift over

dbSNP: rs774949203; hg19: chr16-23649285;