chr13-48377034-G-C

Position:

• chr13-48377034-G-C

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Moderate

The NM_000321.3(RB1):​c.1332G>C​(p.Gln444His) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. Q444R) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: RB1 NM_000321.3 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 6.95

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]

LOC112268118 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PM1: In a region_of_interest Domain A (size 206) in uniprot entity RB_HUMAN there are 18 pathogenic changes around while only 0 benign (100%) in NM_000321.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr13-48377033-A-G is described in Lovd as [Pathogenic].
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 13-48377034-G-C is Pathogenic according to our data. Variant chr13-48377034-G-C is described in ClinVar as [Pathogenic]. Clinvar id is 527917.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
RB1	NM_000321.3	c.1332G>C	p.Gln444His	missense_variant, splice_region_variant	13/27	ENST00000267163.6	NP_000312.2
LOC112268118	XR_002957522.2	n.41-2794C>G		intron_variant, non_coding_transcript_variant
RB1	NM_001407165.1	c.1332G>C	p.Gln444His	missense_variant, splice_region_variant	13/27		NP_001394094.1
RB1	NM_001407166.1	c.1332G>C	p.Gln444His	missense_variant, splice_region_variant	13/17		NP_001394095.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
RB1	ENST00000267163.6	c.1332G>C	p.Gln444His	missense_variant, splice_region_variant	13/27	1	NM_000321.3	ENSP00000267163	P1
RB1	ENST00000650461.1	c.1332G>C	p.Gln444His	missense_variant, splice_region_variant	13/27			ENSP00000497193

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Retinoblastoma Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 30, 2023

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glutamine, which is neutral and polar, with histidine, which is basic and polar, at codon 444 of the RB1 protein (p.Gln444His). This variant also falls at the last nucleotide of exon 13, which is part of the consensus splice site for this exon. This missense change has been observed in individual(s) with bilateral retinoblastoma (PMID: 18181215, 21520333; Invitae). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 527917). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. Experimental studies are conflicting or provide insufficient evidence to determine the effect of this variant on RB1 function (PMID: 18181215). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.48
BayesDel_addAF	Pathogenic	0.19	D
BayesDel_noAF	Uncertain	0.030
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.81	D;.
Eigen	Pathogenic	0.82
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.86	D;D
M_CAP	Uncertain	0.14	D
MetaRNN	Uncertain	0.60	D;D
MetaSVM	Uncertain	0.66	D
MutationAssessor	Uncertain	2.3	M;.
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.54	T
PROVEAN	Uncertain	-2.8	D;.
REVEL	Uncertain	0.63
Sift	Uncertain	0.015	D;.
Sift4G	Uncertain	0.0040	D;.
Polyphen		1.0	D;.
Vest4		0.50
MutPred		0.53		Gain of catalytic residue at S443 (P = 0);Gain of catalytic residue at S443 (P = 0);
MVP		0.83
MPC		1.2
ClinPred		0.98	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.70
gMVP		0.49

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.93		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.93		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555286250; hg19: chr13-48951170;