NM_000321.3:c.1472T>A

Variant names:

• chr13-48380215-T-A
• rs587778848
• NM_000321.3:c.1472T>A

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_000321.3(RB1):​c.1472T>A​(p.Leu491His) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic 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. L491P) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 31)
• Consequence: RB1 NM_000321.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.14
• Publications: 6 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 6 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 29 uncertain in NM_000321.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.881

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.1472T>A	p.Leu491His	missense	Exon 16 of 27	NP_000312.2
	RB1	NM_001407165.1		c.1472T>A	p.Leu491His	missense	Exon 16 of 27	NP_001394094.1
	RB1	NM_001407166.1		c.1472T>A	p.Leu491His	missense	Exon 16 of 17	NP_001394095.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	RB1	ENST00000267163.6	TSL:1 MANE Select	c.1472T>A	p.Leu491His	missense	Exon 16 of 27	ENSP00000267163.4
	RB1	ENST00000467505.6	TSL:1	n.*840T>A		non_coding_transcript_exon	Exon 11 of 22	ENSP00000434702.1
	RB1	ENST00000467505.6	TSL:1	n.*840T>A		3_prime_UTR	Exon 11 of 22	ENSP00000434702.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Retinoblastoma Uncertain:1

Mar 14, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces leucine, which is neutral and non-polar, with histidine, which is basic and polar, at codon 491 of the RB1 protein (p.Leu491His). 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: 574112). 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) performed at Invitae indicates that this missense variant is expected to disrupt RB1 protein function with a positive 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

Feb 12, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.L491H variant (also known as c.1472T>A), located in coding exon 16 of the RB1 gene, results from a T to A substitution at nucleotide position 1472. The leucine at codon 491 is replaced by histidine, an amino acid with similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.91
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.23
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.93	D
Eigen	Pathogenic	0.80
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.89	D
M_CAP	Pathogenic	0.41	D
MetaRNN	Pathogenic	0.88	D
MetaSVM	Uncertain	0.77	D
MutationAssessor	Uncertain	2.6	M
PhyloP100		7.1
PrimateAI	Uncertain	0.60	T
PROVEAN	Pathogenic	-5.2	D
REVEL	Pathogenic	0.82
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.78
MutPred		0.61		Gain of catalytic residue at L491 (P = 2e-04)
MVP		0.94
MPC		1.5
ClinPred		1.0	D
GERP RS		5.7
Varity_R		0.98
gMVP		0.75
Mutation Taster		=16/84	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs587778848; hg19: chr13-48954351;