NM_000321.3:c.905C>G

Variant names:

• chr13-48364937-C-G
• rs1208736713
• NM_000321.3:c.905C>G

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP3

The NM_000321.3(RB1):​c.905C>G​(p.Ser302Cys) variant causes a missense change. The variant allele was found at a frequency of 0.00000352 in 1,418,484 control chromosomes in the GnomAD database, with no homozygous occurrence. There is a variant allele frequency bias in the population database for this variant (GnomAdExome4), which may indicate mosaicism or somatic mutations in the reference population data. 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. S302Y) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000035 (0 hom.)
• Consequence: RB1 NM_000321.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.61
• 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

LOC112268118 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.753

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
RB1	NM_000321.3	c.905C>G	p.Ser302Cys	missense_variant	Exon 9 of 27	ENST00000267163.6	NP_000312.2
RB1	NM_001407165.1	c.905C>G	p.Ser302Cys	missense_variant	Exon 9 of 27		NP_001394094.1
RB1	NM_001407166.1	c.905C>G	p.Ser302Cys	missense_variant	Exon 9 of 17		NP_001394095.1
LOC112268118	XR_002957522.2	n.161G>C		non_coding_transcript_exon_variant	Exon 3 of 3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
RB1	ENST00000267163.6	c.905C>G	p.Ser302Cys	missense_variant	Exon 9 of 27	1	NM_000321.3	ENSP00000267163.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000352 AC: 5 AN: 1418484 Hom.: 0 Cov.: 30 AF XY: 0.00000285 AC XY: 2 AN XY: 702190

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 31920

American (AMR) AF: 0.00 AC: 0 AN: 41826

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25348

East Asian (EAS) AF: 0.00 AC: 0 AN: 37572

South Asian (SAS) AF: 0.00 AC: 0 AN: 81648

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 50536

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5514

European-Non Finnish (NFE) AF: 0.00000368 AC: 4 AN: 1085836

Other (OTH) AF: 0.0000172 AC: 1 AN: 58284

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.00000494837), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Retinoblastoma Uncertain:1

Oct 20, 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. 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. This variant has not been reported in the literature in individuals affected with RB1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces serine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 302 of the RB1 protein (p.Ser302Cys). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Pathogenic	0.19	D
BayesDel_noAF	Uncertain	0.030
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.85	D;.
Eigen	Pathogenic	0.77
Eigen_PC	Pathogenic	0.77
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.81	T;T
M_CAP	Uncertain	0.18	D
MetaRNN	Pathogenic	0.75	D;D
MetaSVM	Pathogenic	0.85	D
MutationAssessor	Uncertain	2.3	M;.
PhyloP100		5.6
PrimateAI	Uncertain	0.60	T
PROVEAN	Benign	-2.0	N;.
REVEL	Pathogenic	0.68
Sift	Uncertain	0.0080	D;.
Sift4G	Uncertain	0.0060	D;.
Polyphen		1.0	D;.
Vest4		0.66
MutPred		0.51		Gain of catalytic residue at M300 (P = 0);Gain of catalytic residue at M300 (P = 0);
MVP		0.86
MPC		1.3
ClinPred		0.96	D
GERP RS		5.6
Varity_R		0.45
gMVP		0.49
Mutation Taster		=39/61	disease causing

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: rs1208736713; hg19: chr13-48939073;