rs1556860663

chrX-47605381-T-A

Variant summary

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

The NM_006950.3(SYN1):c.528-2A>T variant causes a splice acceptor 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 Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 22)
• Consequence: SYN1 NM_006950.3 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.82

Genes affected

SYN1 (HGNC:11494): (synapsin I) This gene is a member of the synapsin gene family. Synapsins encode neuronal phosphoproteins which associate with the cytoplasmic surface of synaptic vesicles. Family members are characterized by common protein domains, and they are implicated in synaptogenesis and the modulation of neurotransmitter release, suggesting a potential role in several neuropsychiatric diseases. This member of the synapsin family plays a role in regulation of axonogenesis and synaptogenesis. The protein encoded serves as a substrate for several different protein kinases and phosphorylation may function in the regulation of this protein in the nerve terminal. Mutations in this gene may be associated with X-linked disorders with primary neuronal degeneration such as Rett syndrome. Alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 22 ACMG points.

• PVS1: Splicing variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal 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 X-47605381-T-A is Pathogenic according to our data. Variant chrX-47605381-T-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 465099.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SYN1	NM_006950.3	c.528-2A>T		splice_acceptor_variant		ENST00000295987.13
SYN1	NM_133499.2	c.528-2A>T		splice_acceptor_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SYN1	ENST00000295987.13	c.528-2A>T		splice_acceptor_variant		2	NM_006950.3	P3
SYN1	ENST00000340666.5	c.528-2A>T		splice_acceptor_variant		1		A1
SYN1	ENST00000639776.1	c.187-2A>T		splice_acceptor_variant		3
SYN1	ENST00000638337.1	n.71-2A>T		splice_acceptor_variant, non_coding_transcript_variant		2

Frequencies

GnomAD3 genomes Cov.: 22

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 22

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	May 01, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Oct 25, 2021	Canonical splice site variant predicted to result in a null allele in a gene for which loss-of-function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (Lek et al., 2016); Has not been previously published as pathogenic or benign to our knowledge -

Epilepsy, X-linked 1, with variable learning disabilities and behavior disorders Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Institute for Human Genetics, University Hospital Essen	Jul 30, 2022	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Invitae	Aug 16, 2022	In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely 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: 465099). This variant has not been reported in the literature in individuals affected with SYN1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change affects an acceptor splice site in intron 3 of the SYN1 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 SYN1 are known to be pathogenic (PMID: 14985377, 21441247). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.28
Cadd	Pathogenic	33
Dann	Uncertain	0.99
FATHMM_MKL	Pathogenic	0.98	D
MutationTaster	Benign	1.0	D;D
GERP RS		5.4

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.76		Position offset: -12
DS_AL_spliceai		1.0		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: rs1556860663; hg19: chrX-47464780;