13-48465369-G-C

Variant names:

• chr13-48465369-G-C
• rs764754259
• NM_000321.3:c.2489+1G>C

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000321.3(RB1):​c.2489+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 Pathogenic (★★).

• Frequency: Genomes: not found (cov: 29)
• Consequence: RB1 NM_000321.3 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 8.71
• Publications: 2 publications found

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]

RB1 Gene-Disease associations (from GenCC):

• hereditary retinoblastoma

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, G2P, Ambry Genetics
• retinoblastoma

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• melanoma

  Inheritance: AD Classification: MODERATE Submitted by: Ambry Genetics

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 5.4, offset of -37, new splice context is: aagGTctgc. 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 13-48465369-G-C is Pathogenic according to our data. Variant chr13-48465369-G-C is described in ClinVar as Pathogenic. ClinVar VariationId is 287433.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000321.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	RB1	NM_000321.3	MANE Select	c.2489+1G>C		splice_donor intron	N/A	NP_000312.2
	RB1	NM_001407165.1		c.2489+1G>C		splice_donor intron	N/A	NP_001394094.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	RB1	ENST00000267163.6	TSL:1 MANE Select	c.2489+1G>C		splice_donor intron	N/A	ENSP00000267163.4
	RB1	ENST00000467505.6	TSL:1	n.*1857+1G>C		splice_donor intron	N/A	ENSP00000434702.1
	RB1	ENST00000650461.1		c.2489+1G>C		splice_donor intron	N/A	ENSP00000497193.1

Frequencies

GnomAD3 genomes Cov.: 29

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 29

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Retinoblastoma Pathogenic:1

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:2, UNILATERAL CASES:0, TOTAL CASES:2, PEDIGREES:2. ACMG Codes Applied:PVS1, PM2

not provided Pathogenic:1

Apr 20, 2016

Eurofins Ntd Llc (ga)

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Hereditary cancer-predisposing syndrome Pathogenic:1

Nov 14, 2016

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2489+1G>C intronic pathogenic mutation results from a G to C substitution one nucleotide after coding exon 23 of the RB1 gene. This pathogenic mutation has been reported in multiple unrelated individuals diagnosed with retinoblastoma (Richter S et al. Am. J. Hum. Genet. 2003 Feb;72:253-69; Tsai T et al. Arch. Ophthalmol. 2004 Feb;122:239-48; Abouzeid H et al. Mol. Vis. 2007 Sep;13:1740-5). Of note, this alteration has been referred to as g.162368G>C and 2627+1G>C in some literature. In addition to the clinical data presented in the literature, 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. As such, this alteration is classified as a disease-causing mutation.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.29
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	1.0	D
PhyloP100		8.7
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.96		Position offset: -1

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

Other links and lift over

dbSNP: rs764754259; hg19: chr13-49039505; COSMIC: COSV57300119;