13-48465112-G-C

Position:

• chr13-48465112-G-C

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_000321.3(RB1):​c.2325+1G>C variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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 Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 28)
• Consequence: RB1 NM_000321.3 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 9.60

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 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.04054539 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-48465112-G-C is Pathogenic according to our data. Variant chr13-48465112-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 428704.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
RB1	NM_000321.3	c.2325+1G>C		splice_donor_variant, intron_variant		ENST00000267163.6	NP_000312.2
RB1	NM_001407165.1	c.2325+1G>C		splice_donor_variant, intron_variant			NP_001394094.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
RB1	ENST00000267163.6	c.2325+1G>C		splice_donor_variant, intron_variant		1	NM_000321.3	ENSP00000267163.4
RB1	ENST00000650461.1	c.2325+1G>C		splice_donor_variant, intron_variant				ENSP00000497193.1
RB1	ENST00000643064.1	c.192+83669G>C		intron_variant				ENSP00000496005.1

Frequencies

GnomAD3 genomes Cov.: 28

GnomAD4 exome Cov.: 35

GnomAD4 genome Cov.: 28

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Retinoblastoma Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Genetic Diagnostic Laboratory, University of Pennsylvania School of Medicine	May 20, 2024	Case and Pedigree Information: BILATERAL CASES:1, UNILATERAL CASES:1, TOTAL CASES:2, PEDIGREES:2. ACMG Codes Applied:PVS1, PM2 -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Mar 13, 2022	For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 428704). This variant is also known as g.162111G>C. Disruption of this splice site has been observed in individual(s) with bilateral retinoblastoma (PMID: 15884040, 28193182). In at least one individual the variant was observed to be de novo. This variant is not present in population databases (gnomAD no frequency). This sequence change affects a donor splice site in intron 22 of the RB1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in RB1 are known to be pathogenic (PMID: 17096365). -

Hereditary cancer-predisposing syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 18, 2014

The c.2325+1G>C intronic variant results from a G to C substitution one nucleotide after coding exon 22 of the RB1 gene. This variant was not reported in population based cohorts in the following databases: Database of Single Nucleotide Polymorphisms (dbSNP), NHLBI Exome Sequencing Project (ESP), and 1000 Genomes Project. In the ESP, this variant was not observed in 6,503 samples (13,006 alleles) with coverage at this position. To date, this alteration has been detected with an allele frequency of approximately 0.25% (greater than 400 alleles tested) in our clinical cohort. This nucleotide position is highly conserved in available vertebrate species. Using the ESEfinder splice site prediction tools, this alteration is predicted to abolish the native donor splice site; however, direct evidence is unavailable. Alterations that disrupt the canonical splice donor site are typically deleterious in nature (ACMG Recommendations for Standards for Interpretation and Reporting of Sequence Variations. Revision 2007. Genet Med. 2008;10:294). As such, the c.2325+1G>C variant is classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.17
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
GERP RS		5.5

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_DG_spliceai		0.29		Position offset: 10
DS_DL_spliceai		0.98		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: rs1131690882; hg19: chr13-49039248;