chr17-3498971-CTG-C

Position:

• chr17-3498971-CTG-C

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000049.4(ASPA):​c.827_828del​(p.Cys276TyrfsTer9) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: ASPA NM_000049.4 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 3.18

Genes affected

ASPA (HGNC:756): (aspartoacylase) This gene encodes an enzyme that catalyzes the conversion of N-acetyl_L-aspartic acid (NAA) to aspartate and acetate. NAA is abundant in the brain where hydrolysis by aspartoacylase is thought to help maintain white matter. This protein is an NAA scavenger in other tissues. Mutations in this gene cause Canavan disease. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Jul 2008]

SPATA22 (HGNC:30705): (spermatogenesis associated 22) Predicted to be involved in regulation of meiotic cell cycle. Predicted to act upstream of or within several processes, including fertilization; gamete generation; and meiosis I cell cycle process. Predicted to be located in chromosome. [provided by Alliance of Genome Resources, Apr 2022]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. There are 23 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 17-3498971-CTG-C is Pathogenic according to our data. Variant chr17-3498971-CTG-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 371202.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr17-3498971-CTG-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ASPA	NM_000049.4	c.827_828del	p.Cys276TyrfsTer9	frameshift_variant	6/6	ENST00000263080.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ASPA	ENST00000263080.3	c.827_828del	p.Cys276TyrfsTer9	frameshift_variant	6/6	1	NM_000049.4	P1
ASPA	ENST00000456349.6	c.827_828del	p.Cys276TyrfsTer9	frameshift_variant	7/7	1		P1
SPATA22	ENST00000541913.5	c.-74+14439_-74+14440del		intron_variant		2
SPATA22	ENST00000570318.1	c.-74+14638_-74+14639del		intron_variant		2

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Spongy degeneration of central nervous system Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 11, 2021	For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Ala305 amino acid residue in ASPA. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 8023850, 22850825, 10909858, 16217711, 22750302, 8023850). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. This variant has been observed in individual(s) with Canavan disease (PMID: 7668285). This variant is also known as 827delGT in the literature. ClinVar contains an entry for this variant (Variation ID: 371202). This variant is not present in population databases (ExAC no frequency). This sequence change creates a premature translational stop signal (p.Cys276Tyrfs*9) in the ASPA gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 38 amino acid(s) of the ASPA protein. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Jul 26, 2016	- -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1057517085; hg19: chr17-3402265;