rs1555793361

Positions:

• chr19-50416529-G-A
• chr19-50416529-G-C

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP3_Moderate

The NM_002691.4(POLD1):​c.2953+1G>A variant causes a splice donor change. The variant allele was found at a frequency of 0.000000714 in 1,400,194 control chromosomes in the GnomAD database, with no homozygous occurrence. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 7.1e-7 (0 hom.)
• Consequence: POLD1 NM_002691.4 splice_donor
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.13

Genes affected

POLD1 (HGNC:9175): (DNA polymerase delta 1, catalytic subunit) This gene encodes the 125-kDa catalytic subunit of DNA polymerase delta. DNA polymerase delta possesses both polymerase and 3' to 5' exonuclease activity and plays a critical role in DNA replication and repair. Alternatively spliced transcript variants have been observed for this gene, and a pseudogene of this gene is located on the long arm of chromosome 6. [provided by RefSeq, Mar 2012]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Splicing variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal 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.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
POLD1	NM_002691.4	c.2953+1G>A		splice_donor_variant		ENST00000440232.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
POLD1	ENST00000440232.7	c.2953+1G>A		splice_donor_variant		1	NM_002691.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 7.14e-7 AC: 1 AN: 1400194 Hom.: 0 Cov.: 31 AF XY: 0.00000145 AC XY: 1 AN XY: 691416

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: 9.24e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Colorectal cancer, susceptibility to, 10 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 28, 2023

This sequence change affects a donor splice site in intron 23 of the POLD1 gene. Missense variants that disrupt the 3'-5' exonuclease (proof-reading) activity of the POLD1 protein are associated with PPAP (polymerase proofreading–associated polyposis) (PMID: 23263490, 23447401). However, loss-of-function variants that result in an absent or severely disrupted POLD1 protein, and missense variants outside the exonuclease domain, are unlikely to be associated with PPAP. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with POLD1-related conditions. ClinVar contains an entry for this variant (Variation ID: 469313). Studies have shown that disruption of this splice site results in skipping of exon 23 and introduces a premature termination codon (Invitae). The resulting mRNA is expected to undergo nonsense-mediated decay. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 19, 2016

The c.2953+1G>A intronic variant results from a G to A substitution one nucleotide after coding exon 22 of the POLD1 gene. This nucleotide position is highly conserved in available vertebrate species. Using the BDGP and ESEfinder splice site prediction tools, this alteration is not predicted to have any significant effect on this splice donor site; however, direct evidence is unavailable. 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. However, loss of function of POLD1 has not been clearly established as a mechanism of disease. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.11	D
BayesDel_noAF	Uncertain	-0.070
CADD	Pathogenic	29
DANN	Uncertain	0.98
Eigen	Pathogenic	0.85
Eigen_PC	Uncertain	0.59
FATHMM_MKL	Uncertain	0.95	D
MutationTaster	Benign	1.0	D
GERP RS		2.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.85
SpliceAI score (max)		0.95		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.95		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: rs1555793361; hg19: chr19-50919786; COSMIC: COSV54529447; COSMIC: COSV54529447;