13-48463758-T-G

Variant names:

• chr13-48463758-T-G
• rs137853296
• NM_000321.3:c.2134T>G

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1 PM2 PM5 PP3_Moderate

The NM_000321.3(RB1):​c.2134T>G​(p.Cys712Gly) variant causes a missense 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. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C712R) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: RB1 NM_000321.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.65
• 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: Likely_pathogenic. The variant received 8 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 16 uncertain in NM_000321.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr13-48463758-T-C is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 13092.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.92

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
RB1	NM_000321.3	c.2134T>G	p.Cys712Gly	missense_variant	Exon 21 of 27	ENST00000267163.6	NP_000312.2
RB1	NM_001407165.1	c.2134T>G	p.Cys712Gly	missense_variant	Exon 21 of 27		NP_001394094.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
RB1	ENST00000267163.6	c.2134T>G	p.Cys712Gly	missense_variant	Exon 21 of 27	1	NM_000321.3	ENSP00000267163.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 28

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Retinoblastoma Uncertain:1

Mar 07, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. This sequence change replaces cysteine, which is neutral and slightly polar, with glycine, which is neutral and non-polar, at codon 712 of the RB1 protein (p.Cys712Gly). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with RB1-related conditions. ClinVar contains an entry for this variant (Variation ID: 1052825). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. This variant disrupts the p.Cys712 amino acid residue in RB1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 9671401, 10671068, 11668642, 22084214). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. -

Hereditary cancer-predisposing syndrome Uncertain:1

Jun 06, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.C712G variant (also known as c.2134T>G), located in coding exon 21 of the RB1 gene, results from a T to G substitution at nucleotide position 2134. The cysteine at codon 712 is replaced by glycine, an amino acid with highly dissimilar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.87
BayesDel_addAF	Pathogenic	0.48	D
BayesDel_noAF	Pathogenic	0.45
CADD	Pathogenic	31
DANN	Uncertain	0.98
DEOGEN2	Pathogenic	0.91	D;.
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.92	D;D
M_CAP	Pathogenic	0.37	D
MetaRNN	Pathogenic	0.92	D;D
MetaSVM	Pathogenic	0.92	D
MutationAssessor	Pathogenic	3.0	M;.
PhyloP100		7.7
PrimateAI	Pathogenic	0.80	D
PROVEAN	Pathogenic	-8.8	D;.
REVEL	Pathogenic	0.95
Sift	Uncertain	0.013	D;.
Sift4G	Pathogenic	0.0	D;.
Polyphen		1.0	D;.
Vest4		0.93
MutPred		0.70		Gain of catalytic residue at G710 (P = 0);Gain of catalytic residue at G710 (P = 0);
MVP		0.97
MPC		1.4
ClinPred		1.0	D
GERP RS		6.1
Varity_R		0.92
gMVP		0.82
Mutation Taster		=3/97	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs137853296; hg19: chr13-49037894;