chr13-48380164-G-A

Variant names:

• chr13-48380164-G-A
• rs1461382798
• NM_000321.3:c.1422-1G>A

Variant summary

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

The NM_000321.3(RB1):​c.1422-1G>A variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000706 in 1,415,758 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 Pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 7.1e-7 (0 hom.)
• Consequence: RB1 NM_000321.3 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 8.92

Genes affected

RB1 (HGNC:9884): (RB transcriptional corepressor 1) The protein encoded by this gene is a negative regulator of the cell cycle and was the first tumor suppressor gene found. The encoded protein also stabilizes constitutive heterochromatin to maintain the overall chromatin structure. The active, hypophosphorylated form of the protein binds transcription factor E2F1. Defects in this gene are a cause of childhood cancer retinoblastoma (RB), bladder cancer, and osteogenic sarcoma. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 7.1, offset of -37, new splice context is: aaatttttttctttttatAGaag. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-48380164-G-A is Pathogenic according to our data. Variant chr13-48380164-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 527931.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
RB1	NM_000321.3	c.1422-1G>A		splice_acceptor_variant, intron_variant	Intron 15 of 26	ENST00000267163.6	NP_000312.2
RB1	NM_001407165.1	c.1422-1G>A		splice_acceptor_variant, intron_variant	Intron 15 of 26		NP_001394094.1
RB1	NM_001407166.1	c.1422-1G>A		splice_acceptor_variant, intron_variant	Intron 15 of 16		NP_001394095.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
RB1	ENST00000267163.6	c.1422-1G>A		splice_acceptor_variant, intron_variant	Intron 15 of 26	1	NM_000321.3	ENSP00000267163.4
RB1	ENST00000650461.1	c.1422-1G>A		splice_acceptor_variant, intron_variant	Intron 15 of 26			ENSP00000497193.1

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome AF: 7.06e-7 AC: 1 AN: 1415758 Hom.: 0 Cov.: 31 AF XY: 0.00000142 AC XY: 1 AN XY: 702940

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: 9.18e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 30

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Retinoblastoma Pathogenic:2

Jul 29, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects an acceptor splice site in intron 15 of the RB1 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. This variant is not present in population databases (ExAC no frequency). This variant has been reported in individuals affected with bilateral retinoblastoma (PMID: 15884040, Invitae). This variant is also known as c.1560-1G>A in the literature. ClinVar contains an entry for this variant (Variation ID: 527931). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. Donor and acceptor splice site variants typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in RB1 are known to be pathogenic (PMID: 17096365). For these reasons, this variant has been classified as Pathogenic. -

May 20, 2024

Genetic Diagnostic Laboratory, University of Pennsylvania School of Medicine

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Case and Pedigree Information: BILATERAL CASES:1, UNILATERAL CASES:0, TOTAL CASES:1, PEDIGREES:1. ACMG Codes Applied:PVS1, PM2 -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.40
CADD	Pathogenic	33
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
GERP RS		5.9

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.91		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.91		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: rs1461382798; hg19: chr13-48954300; COSMIC: COSV57314130; COSMIC: COSV57314130;