NM_000321.3:c.2212-1G>C

Variant names:

• chr13-48464997-G-C
• rs587776786
• NM_000321.3:c.2212-1G>C

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PVS1_Moderate PM2 PP5_Moderate

The NM_000321.3(RB1):​c.2212-1G>C variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency:
  • Genomes: 𝑓 0.0 (0 hom., cov: 22)
  • Failed GnomAD Quality Control
• Consequence: RB1 NM_000321.3 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.60
• Publications: 1 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.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.040904198 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-48464997-G-C is Pathogenic according to our data. Variant chr13-48464997-G-C is described in ClinVar as [Pathogenic]. Clinvar id is 1076417.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
RB1	NM_000321.3	c.2212-1G>C		splice_acceptor_variant, intron_variant	Intron 21 of 26	ENST00000267163.6	NP_000312.2
RB1	NM_001407165.1	c.2212-1G>C		splice_acceptor_variant, intron_variant	Intron 21 of 26		NP_001394094.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
RB1	ENST00000267163.6	c.2212-1G>C		splice_acceptor_variant, intron_variant	Intron 21 of 26	1	NM_000321.3	ENSP00000267163.4

Frequencies

GnomAD3 genomes AF: 0.00 AC: 0 AN: 98684 Hom.: 0 Cov.: 22

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 25

GnomAD4 genome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 98684 Hom.: 0 Cov.: 22 AF XY: 0.00 AC XY: 0 AN XY: 44270

African (AFR) AF: 0.00 AC: 0 AN: 27316

American (AMR) AF: 0.00 AC: 0 AN: 6412

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 2854

East Asian (EAS) AF: 0.00 AC: 0 AN: 2934

South Asian (SAS) AF: 0.00 AC: 0 AN: 2920

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 1850

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 78

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 52360

Other (OTH) AF: 0.00 AC: 0 AN: 1238

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Retinoblastoma Pathogenic:1

Aug 16, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Disruption of this splice site has been observed in individual(s) with bilateral retinoblastomas (PMID: 25712084, Invitae). Experimental studies have shown that disruption of this splice site disrupts mRNA splicing (PMID: 2601691). Donor and acceptor splice site variants typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in RB1 are known to be pathogenic (PMID: 17096365). For these reasons, this variant has been classified as Pathogenic. This variant is not present in population databases (ExAC no frequency). This sequence change affects an acceptor splice site in intron 21 of the RB1 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.24
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
PhyloP100		9.6
GERP RS		5.3
Mutation Taster		=1/99	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.23		Position offset: 26
DS_AL_spliceai		0.98		Position offset: 1

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

Other links and lift over

dbSNP: rs587776786; hg19: chr13-49039133; COSMIC: COSV57303754;