Genetic Variant RB1-DT:n.38C>A (chr13-48303686-G-T) – ACMG Classification: Likely_benign (-2 pts)

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2BP4_Strong

The ENST00000433480.4(RB1-DT):n.38C>A variant causes a non coding transcript exon change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000215 in 465,444 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

RB1-DT
ENST00000433480.4 non_coding_transcript_exon

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 1.48

Publications

0 publications found

Variant links:

Genes affected

RB1-DT (HGNC:42778): (RB1 divergent transcript)

RB1-DT links:

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

RB1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.47).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
RB1	NM_000321.3 link	c.-227G>T		upstream_gene_variant		ENST00000267163.6	NP_000312.2	P06400A0A024RDV3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
RB1	ENST00000267163.6 link	c.-227G>T		upstream_gene_variant		1	NM_000321.3	ENSP00000267163.4		P06400

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000215

AC:

AN:

465444

Hom.:

Cov.:

AF XY:

0.00000413

AC XY:

AN XY:

242034

show subpopulations

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

African (AFR)

AF:

0.00

AC:

AN:

9146

American (AMR)

AF:

0.00

AC:

AN:

9694

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

12226

East Asian (EAS)

AF:

0.00

AC:

AN:

23484

South Asian (SAS)

AF:

0.00

AC:

AN:

41108

European-Finnish (FIN)

AF:

0.00

AC:

AN:

27346

Middle Eastern (MID)

AF:

0.00

AC:

AN:

1938

European-Non Finnish (NFE)

AF:

0.00000317

AC:

AN:

315180

Other (OTH)

AF:

0.00

AC:

AN:

25322

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.225

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Retinoblastoma

Uncertain:1

Nov 15, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant occurs in a non-coding region of the RB1 gene. It does not change the encoded amino acid sequence of the RB1 protein. 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. Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. 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

BayesDel_noAF

Benign

-0.47

CADD

Benign

(source)

DANN

Benign

0.88

PhyloP100

1.5

PromoterAI

0.022

Neutral

(source)

Splicing

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

Publications

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chr13-48303686-G-T

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over