chr13-48465238-C-G

Position:

• chr13-48465238-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PM2

The NM_000321.3(RB1):​c.2359C>G​(p.Arg787Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 29)
• Consequence: RB1 NM_000321.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 2.20

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 Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a region_of_interest Domain C; mediates interaction with E4F1 (size 157) in uniprot entity RB_HUMAN there are 8 pathogenic changes around while only 0 benign (100%) in NM_000321.3
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
RB1	NM_000321.3	c.2359C>G	p.Arg787Gly	missense_variant	23/27	ENST00000267163.6	NP_000312.2
RB1	NM_001407165.1	c.2359C>G	p.Arg787Gly	missense_variant	23/27		NP_001394094.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
RB1	ENST00000267163.6	c.2359C>G	p.Arg787Gly	missense_variant	23/27	1	NM_000321.3	ENSP00000267163.4
RB1	ENST00000650461.1	c.2359C>G	p.Arg787Gly	missense_variant	23/27			ENSP00000497193.1
RB1	ENST00000643064.1	c.192+83795C>G		intron_variant				ENSP00000496005.1

Frequencies

GnomAD3 genomes Cov.: 29

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 29

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Retinoblastoma Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 25, 2023

This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 787 of the RB1 protein (p.Arg787Gly). 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: 1020960). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on RB1 protein function. 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. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 05, 2024

The p.R787G variant (also known as c.2359C>G), located in coding exon 23 of the RB1 gene, results from a C to G substitution at nucleotide position 2359. The arginine at codon 787 is replaced by glycine, an amino acid with dissimilar properties. This amino acid position is well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. 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	Benign	0.17
BayesDel_addAF	Uncertain	0.082	D
BayesDel_noAF	Benign	-0.12
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.52	D;.
Eigen	Uncertain	0.53
Eigen_PC	Uncertain	0.58
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.94	D;D
M_CAP	Benign	0.070	D
MetaRNN	Uncertain	0.51	D;D
MetaSVM	Uncertain	0.087	D
MutationAssessor	Benign	1.0	L;.
PrimateAI	Uncertain	0.59	T
PROVEAN	Benign	-1.7	N;.
REVEL	Uncertain	0.50
Sift	Uncertain	0.019	D;.
Sift4G	Uncertain	0.038	D;.
Polyphen		0.98	D;.
Vest4		0.51
MutPred		0.59		Gain of catalytic residue at R787 (P = 9e-04);Gain of catalytic residue at R787 (P = 9e-04);
MVP		0.82
MPC		1.1
ClinPred		0.83	D
GERP RS		5.9
Varity_R		0.62
gMVP		0.53

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs137853293; hg19: chr13-49039374;