8-99818712-G-T

Position:

• chr8-99818712-G-T

Variant summary

Our verdict is Pathogenic. Variant got 22 ACMG points: 22P and 0B. PVS1 PM2 PP3_Strong PP5_Very_Strong

The NM_017890.5(VPS13B):​c.8521-1G>T variant causes a splice acceptor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,404 control chromosomes in the GnomAD database, with no homozygous occurrence. 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 Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: VPS13B NM_017890.5 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 9.72

Genes affected

VPS13B (HGNC:2183): (vacuolar protein sorting 13 homolog B) This gene encodes a potential transmembrane protein that may function in vesicle-mediated transport and sorting of proteins within the cell. This protein may play a role in the development and the function of the eye, hematological system, and central nervous system. Mutations in this gene have been associated with Cohen syndrome. Multiple splice variants encoding distinct isoforms have been identified for this gene. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 22 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 5.7, offset of 11, new splice context is: tttttatatattgtgttcAGccc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• 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 8-99818712-G-T is Pathogenic according to our data. Variant chr8-99818712-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 459251.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
VPS13B	NM_017890.5	c.8521-1G>T		splice_acceptor_variant		ENST00000358544.7
VPS13B	NM_152564.5	c.8446-1G>T		splice_acceptor_variant		ENST00000357162.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
VPS13B	ENST00000357162.7	c.8446-1G>T		splice_acceptor_variant		1	NM_152564.5	P1
VPS13B	ENST00000358544.7	c.8521-1G>T		splice_acceptor_variant		1	NM_017890.5

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461404 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727038

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

Bravo AF: 0.00000756

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cohen syndrome Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 07, 2022	Variant summary: VPS13B c.8521-1G>T is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: Four predict the variant abolishes the canonical 3' splicing acceptor site. Two predict the variant strengthens an alternate cryptic exonic 3' splice acceptor site. However, these predictions have yet to be confirmed by functional studies. Loss of function variants are associated with Cohen Syndrome in HGMD. The variant was absent in 250248 control chromosomes (gnomAD). To our knowledge, no occurrence of c.8521-1G>T in individuals affected with Cohen Syndrome and no experimental evidence demonstrating its impact on protein function have been reported. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as pathogenic (n=1) and likely pathogenic (n=2). Based on the evidence outlined above, the variant was classified as likely pathogenic. -
Likely pathogenic, no assertion criteria provided	clinical testing	Counsyl	Nov 07, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jul 21, 2023	Disruption of this splice site has been observed in individual(s) with VPS13B-related disease (Invitae). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 459251). This variant is not present in population databases (gnomAD no frequency). This sequence change affects an acceptor splice site in intron 46 of the VPS13B gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in VPS13B are known to be pathogenic (PMID: 15141358, 16648375, 20461111). -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Greenwood Genetic Center Diagnostic Laboratories, Greenwood Genetic Center

Jan 22, 2021

PVS1, PM2 -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.27
CADD	Pathogenic	35
DANN	Uncertain	1.0
Eigen	Pathogenic	1.3
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.98	D
MutationTaster	Benign	1.0	D;D;D
GERP RS		5.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.70		Position offset: 12
DS_AL_spliceai		0.99		Position offset: 1

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554566596; hg19: chr8-100830940;