chr12-6464488-T-C

Position:

• chr12-6464488-T-C

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1_Strong PM2 PP3_Strong

The NM_014231.5(VAMP1):​c.341-2A>G variant causes a splice acceptor change. The variant allele was found at a frequency of 0.000000731 in 1,368,812 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 Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 7.3e-7 (0 hom.)
• Consequence: VAMP1 NM_014231.5 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 5.35

Genes affected

VAMP1 (HGNC:12642): (vesicle associated membrane protein 1) Synapotobrevins, syntaxins, and the synaptosomal-associated protein SNAP25 are the main components of a protein complex involved in the docking and/or fusion of synaptic vesicles with the presynaptic membrane. The protein encoded by this gene is a member of the vesicle-associated membrane protein (VAMP)/synaptobrevin family. Mutations in this gene are associated with autosomal dominant spastic ataxia 1. Multiple alternative splice variants have been described, but the full-length nature of some variants has not been defined. [provided by RefSeq, Jul 2014]

TAPBPL (HGNC:30683): (TAP binding protein like) Tapasin, or TAPBP (MIM 601962), is a member of the variable-constant Ig superfamily that links major histocompatibility complex (MHC) class I molecules to the transporter associated with antigen processing (TAP; see MIM 170260) in the endoplasmic reticulum (ER). The TAPBP gene is located near the MHC complex on chromosome 6p21.3. TAPBPL is a member of the Ig superfamily that is localized on chromosome 12p13.3, a region somewhat paralogous to the MHC.[supplied by OMIM, Mar 2008]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 6.29972 fraction of the gene.
• 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.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
VAMP1	NM_014231.5	c.341-2A>G		splice_acceptor_variant		ENST00000396308.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
VAMP1	ENST00000396308.4	c.341-2A>G		splice_acceptor_variant		2	NM_014231.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 7.31e-7 AC: 1 AN: 1368812 Hom.: 0 Cov.: 34 AF XY: 0.00000149 AC XY: 1 AN XY: 671834

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: 9.39e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Spastic paraplegia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 03, 2023

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. 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. This variant has not been reported in the literature in individuals affected with VAMP1-related conditions. This sequence change affects an acceptor splice site in intron 4 of the VAMP1 gene. While this variant is not anticipated to result in nonsense mediated decay, it likely alters RNA splicing and results in a disrupted protein product. This variant is not present in population databases (gnomAD no frequency). -

Myasthenic syndrome, congenital, 25, presynaptic Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Center For Human Genetics And Laboratory Diagnostics, Dr. Klein, Dr. Rost And Colleagues

Sep 08, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.25
CADD	Pathogenic	33
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.94
FATHMM_MKL	Uncertain	0.93	D
MutationTaster	Benign	1.0	D;D;D;D
GERP RS		5.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		0.95

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.66		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.26		Position offset: -20
DS_AL_spliceai		0.66		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1213158610; hg19: chr12-6573654;