chr22-50626153-C-T

Position:

• chr22-50626153-C-T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The ENST00000216124.10(ARSA):​c.979+1G>A variant causes a splice donor change. The variant allele was found at a frequency of 0.00000414 in 1,449,278 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: 34)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: ARSA ENST00000216124.10 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 4.70

Genes affected

ARSA (HGNC:713): (arylsulfatase A) The protein encoded by this gene hydrolyzes cerebroside sulfate to cerebroside and sulfate. Defects in this gene lead to metachromatic leucodystrophy (MLD), a progressive demyelination disease which results in a variety of neurological symptoms and ultimately death. Alternatively spliced transcript variants have been described for this gene. [provided by RefSeq, Dec 2010]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.081045754 fraction of the gene. Cryptic splice site detected, with MaxEntScore 3, offset of -15, new splice context is: cagGTcata. Cryptic site results in inframe 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
• PP5: Variant 22-50626153-C-T is Pathogenic according to our data. Variant chr22-50626153-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 188949.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr22-50626153-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ARSA	NM_000487.6	c.979+1G>A		splice_donor_variant		ENST00000216124.10	NP_000478.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ARSA	ENST00000216124.10	c.979+1G>A		splice_donor_variant		1	NM_000487.6	ENSP00000216124	P1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD3 exomes AF: 0.00000894 AC: 2 AN: 223794 Hom.: 0 AF XY: 0.00000826 AC XY: 1 AN XY: 121008

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 SAS exome AF: 0.0000716

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000414 AC: 6 AN: 1449278 Hom.: 0 Cov.: 35 AF XY: 0.00000556 AC XY: 4 AN XY: 719870

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: 0.0000714

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Metachromatic leukodystrophy Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 28, 2023	This sequence change affects a donor splice site in intron 5 of the ARSA 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 ARSA are known to be pathogenic (PMID: 8962139, 10477432). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. Disruption of this splice site has been observed in individuals with metachromatic leukodystrophy (PMID: 14517960, 34276053, 34554397). This variant is also known as c.973+1G>A. ClinVar contains an entry for this variant (Variation ID: 188949). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Kasturba Medical College, Manipal, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India	-	- -
Likely pathogenic, no assertion criteria provided	clinical testing	Myelin Disorders Clinic-Children's Medical Center/Medical Genetics Lab-Tarbiat Modares University, Children's Medical Center, Pediatrics Center of Excellence,	-	- -
Likely pathogenic, criteria provided, single submitter	literature only	Counsyl	Aug 28, 2014	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Mar 13, 2023

Reported as c.973+1 G>A and seen with a second ARSA variant, phase unknown, in a patient with juvenile MLD in the published literature (Eng et al., 2003); 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 (gnomAD); This variant is associated with the following publications: (PMID: 34554397, 34276053, 14517960) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.33
CADD	Pathogenic	29
DANN	Uncertain	0.99
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.99	D
MutationTaster	Benign	1.0	D;D;D;D;D;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)		0.84		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.84		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: rs754722529; hg19: chr22-51064581;