13-48476747-A-G

Variant names:

• chr13-48476747-A-G
• rs1555295331
• NM_000321.3:c.2567A>G

Variant summary

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

The NM_000321.3(RB1):​c.2567A>G​(p.Asp856Gly) variant causes a missense change involving the alteration of a 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: 32)
• Consequence: RB1 NM_000321.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.42

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 rank	MANE	Protein	UniProt
RB1	NM_000321.3	c.2567A>G	p.Asp856Gly	missense_variant	Exon 25 of 27	ENST00000267163.6	NP_000312.2
RB1	NM_001407165.1	c.2567A>G	p.Asp856Gly	missense_variant	Exon 25 of 27		NP_001394094.1
RB1	NM_001407168.1	c.17A>G	p.Asp6Gly	missense_variant	Exon 2 of 4		NP_001394097.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
RB1	ENST00000267163.6	c.2567A>G	p.Asp856Gly	missense_variant	Exon 25 of 27	1	NM_000321.3	ENSP00000267163.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Retinoblastoma Uncertain:1

Oct 09, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces aspartic acid with glycine at codon 856 of the RB1 protein (p.Asp856Gly). The aspartic acid residue is moderately conserved and there is a moderate physicochemical difference between aspartic acid and glycine. This variant is not present in population databases (ExAC 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: 527925). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C15"). 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.23
BayesDel_addAF	Uncertain	0.080	D
BayesDel_noAF	Benign	-0.12
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.49	T;.
Eigen	Uncertain	0.61
Eigen_PC	Uncertain	0.66
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.91	D;D
M_CAP	Benign	0.082	D
MetaRNN	Uncertain	0.68	D;D
MetaSVM	Uncertain	0.17	D
MutationAssessor	Benign	1.5	L;.
PrimateAI	Uncertain	0.58	T
PROVEAN	Benign	-1.6	N;.
REVEL	Uncertain	0.59
Sift	Benign	0.076	T;.
Sift4G	Uncertain	0.0060	D;.
Polyphen		0.97	D;.
Vest4		0.39
MutPred		0.60		Gain of catalytic residue at M851 (P = 0);Gain of catalytic residue at M851 (P = 0);
MVP		0.69
MPC		1.3
ClinPred		0.94	D
GERP RS		5.8
Varity_R		0.29
gMVP		0.39

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: rs1555295331; hg19: chr13-49050883;