chr13-48456287-C-A

Variant names:

• chr13-48456287-C-A
• rs587778641
• NM_000321.3:c.1898C>A

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_000321.3(RB1):​c.1898C>A​(p.Thr633Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 17/22 in silico tools predict a benign 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. T633I) has been classified as Likely benign.

• 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: 0.958
• 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: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.1403575).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
RB1	NM_000321.3	c.1898C>A	p.Thr633Asn	missense_variant	Exon 19 of 27	ENST00000267163.6	NP_000312.2
RB1	NM_001407165.1	c.1898C>A	p.Thr633Asn	missense_variant	Exon 19 of 27		NP_001394094.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
RB1	ENST00000267163.6	c.1898C>A	p.Thr633Asn	missense_variant	Exon 19 of 27	1	NM_000321.3	ENSP00000267163.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

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

Jan 13, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine, which is neutral and polar, with asparagine, which is neutral and polar, at codon 633 of the RB1 protein (p.Thr633Asn). 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: 1473716). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt RB1 protein function with a negative predictive value of 80%. 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

Dec 19, 2022

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.T633N variant (also known as c.1898C>A), located in coding exon 19 of the RB1 gene, results from a C to A substitution at nucleotide position 1898. The threonine at codon 633 is replaced by asparagine, an amino acid with similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.073
BayesDel_addAF	Benign	-0.074	T
BayesDel_noAF	Benign	-0.34
CADD	Benign	18
DANN	Benign	0.96
DEOGEN2	Benign	0.37	T;.
Eigen	Benign	-0.36
Eigen_PC	Benign	-0.19
FATHMM_MKL	Benign	0.73	D
LIST_S2	Benign	0.60	T;T
M_CAP	Benign	0.025	D
MetaRNN	Benign	0.14	T;T
MetaSVM	Benign	-0.43	T
MutationAssessor	Benign	1.2	L;.
PhyloP100		0.96
PrimateAI	Benign	0.35	T
PROVEAN	Benign	-0.75	N;.
REVEL	Benign	0.22
Sift	Benign	0.053	T;.
Sift4G	Benign	0.11	T;.
Polyphen		0.029	B;.
Vest4		0.15
MutPred		0.24		Loss of glycosylation at T633 (P = 0.0355);Loss of glycosylation at T633 (P = 0.0355);
MVP		0.77
MPC		0.52
ClinPred		0.20	T
GERP RS		5.1
Varity_R		0.13
gMVP		0.17
Mutation Taster		=92/8	polymorphism

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

Other links and lift over

dbSNP: rs587778641; hg19: chr13-49030423;