chr21-32641896-C-T

Variant names:

• chr21-32641896-C-T
• rs1160685381
• NM_203446.3:c.3588G>A

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_203446.3(SYNJ1):​c.3588G>A​(p.Pro1196Pro) variant causes a splice region, synonymous change. The variant allele was found at a frequency of 0.00000137 in 1,456,408 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign 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: 0.0000014 (0 hom.)
• Consequence: SYNJ1 NM_203446.3 splice_region, synonymous
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.82
• Publications: 1 publications found

Genes affected

SYNJ1 (HGNC:11503): (synaptojanin 1) This gene encodes a phosphoinositide phosphatase that regulates levels of membrane phosphatidylinositol-4,5-bisphosphate. As such, expression of this enzyme may affect synaptic transmission and membrane trafficking. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Sep 2011]

SYNJ1 Gene-Disease associations (from GenCC):

• genetic developmental and epileptic encephalopathy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• developmental and epileptic encephalopathy, 53

  Inheritance: AR Classification: STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
• early-onset Parkinson disease 20

  Inheritance: AR Classification: STRONG, MODERATE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• undetermined early-onset epileptic encephalopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• atypical juvenile parkinsonism

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• young-onset Parkinson disease

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious 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 rank	MANE	Protein	UniProt
SYNJ1	NM_203446.3	c.3588G>A	p.Pro1196Pro	splice_region_variant, synonymous_variant	Exon 29 of 33	ENST00000674351.1	NP_982271.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SYNJ1	ENST00000674351.1	c.3588G>A	p.Pro1196Pro	splice_region_variant, synonymous_variant	Exon 29 of 33		NM_203446.3	ENSP00000501530.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00 AC: 0 AN: 244282 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1456408 Hom.: 0 Cov.: 32 AF XY: 0.00000276 AC XY: 2 AN XY: 724410

African (AFR) AF: 0.00 AC: 0 AN: 33084

American (AMR) AF: 0.00 AC: 0 AN: 44224

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26010

East Asian (EAS) AF: 0.00 AC: 0 AN: 39324

South Asian (SAS) AF: 0.00 AC: 0 AN: 85452

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53234

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5756

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1109242

Other (OTH) AF: 0.00 AC: 0 AN: 60082

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Early-onset Parkinson disease 20;C4479313:Developmental and epileptic encephalopathy, 53 Uncertain:1

Aug 10, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. 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 create or strengthen a splice site. ClinVar contains an entry for this variant (Variation ID: 478344). This variant has not been reported in the literature in individuals affected with SYNJ1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change affects codon 1235 of the SYNJ1 mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the SYNJ1 protein. This variant also falls at the last nucleotide of exon 29, which is part of the consensus splice site for this exon. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.31
CADD	Uncertain	25
DANN	Benign	0.83
PhyloP100		3.8
PromoterAI		-0.11	Neutral

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		0.87		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.87		Position offset: -4

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

Other links and lift over

dbSNP: rs1160685381; hg19: chr21-34014206;