13-48476843-G-C

Variant names:

• chr13-48476843-G-C
• rs1555295354
• NM_000321.3:c.2663G>C

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM2 PM5 PP3_Strong PP5_Moderate

The NM_000321.3(RB1):​c.2663G>C​(p.Ser888Thr) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S888N) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: RB1 NM_000321.3 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.04
• Publications: 0 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 10 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr13-48476843-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 527935.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 13-48476843-G-C is Pathogenic according to our data. Variant chr13-48476843-G-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 3663254.Status of the report is criteria_provided_single_submitter, 1 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.2663G>C	p.Ser888Thr	missense splice_region	Exon 25 of 27	NP_000312.2
	RB1	NM_001407165.1		c.2663G>C	p.Ser888Thr	missense splice_region	Exon 25 of 27	NP_001394094.1
	RB1	NM_001407168.1		c.113G>C	p.Ser38Thr	missense splice_region	Exon 2 of 4	NP_001394097.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	RB1	ENST00000267163.6	TSL:1 MANE Select	c.2663G>C	p.Ser888Thr	missense splice_region	Exon 25 of 27	ENSP00000267163.4
	RB1	ENST00000467505.6	TSL:1	n.*2031G>C		splice_region non_coding_transcript_exon	Exon 20 of 22	ENSP00000434702.1
	RB1	ENST00000484879.1	TSL:1	n.397G>C		splice_region non_coding_transcript_exon	Exon 1 of 3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Retinoblastoma Pathogenic:1

Aug 22, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces serine, which is neutral and polar, with threonine, which is neutral and polar, at codon 888 of the RB1 protein (p.Ser888Thr). This variant also falls at the last nucleotide of exon 25, which is part of the consensus splice site for this exon. This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with bilateral multifocal retinoblastoma (internal data). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant disrupts the c.2663G nucleotide in the RB1 gene. Other variant(s) that disrupt this nucleotide have been determined to be pathogenic (PMID: 9536098, 17576681, 24225018, 27879208, 34190019). This suggests that this nucleotide is clinically significant, and that variants that disrupt this position are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.14
BayesDel_addAF	Uncertain	0.029	T
BayesDel_noAF	Benign	-0.20
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Benign	0.36	T
Eigen	Pathogenic	0.77
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Benign	0.82	T
M_CAP	Uncertain	0.26	D
MetaRNN	Uncertain	0.52	D
MetaSVM	Uncertain	0.38	D
MutationAssessor	Benign	1.1	L
PhyloP100		9.0
PrimateAI	Uncertain	0.55	T
PROVEAN	Benign	-0.65	N
REVEL	Pathogenic	0.68
Sift	Uncertain	0.0090	D
Sift4G	Uncertain	0.018	D
Polyphen		0.97	D
Vest4		0.42
MutPred		0.37		Gain of catalytic residue at L891 (P = 0.0026)
MVP		0.77
MPC		1.0
ClinPred		0.88	D
GERP RS		5.8
Varity_R		0.29
gMVP		0.23
Mutation Taster		=19/81	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.87		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.87		Position offset: 0

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

Other links and lift over

dbSNP: rs1555295354; hg19: chr13-49050979;