22-50627166-C-T

Position:

• chr22-50627166-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP5

The NM_000487.6(ARSA):​c.465G>A​(p.Gln155Gln) variant causes a splice region, synonymous change. The variant was absent in control chromosomes in GnomAD project. 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 Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: ARSA NM_000487.6 splice_region, synonymous
• Scores: Splicing: ADA: 0.9989
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: 5.93

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]

ARSA (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 22-50627166-C-T is Pathogenic according to our data. Variant chr22-50627166-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 166691.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Likely_pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ARSA	NM_000487.6	c.465G>A	p.Gln155Gln	splice_region_variant, synonymous_variant	2/8	ENST00000216124.10	NP_000478.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ARSA	ENST00000216124.10	c.465G>A	p.Gln155Gln	splice_region_variant, synonymous_variant	2/8	1	NM_000487.6	ENSP00000216124.5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Metachromatic leukodystrophy Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 25, 2024

This sequence change affects codon 155 of the ARSA mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the ARSA protein. This variant also falls at the last nucleotide of exon 2, which is part of the consensus splice site for this exon. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with metachromatic leukodystrophy (PMID: 30057904). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 166691). 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 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. -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Aug 19, 2021

Variant summary: ARSA c.465G>A (p.Gln155Gln) alters a conserved nucleotide located as the last nucleotide of exon 2 adjacent to the intronic canonical splice donor site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: Three predict the variant weakens a canonical 5' splice donor site. One predicts the variant abolishes a canonical 5' splicing donor site. However, these predictions have yet to be confirmed by traceable functional studies. The variant was absent in 240440 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.465G>A has been reported in the literature as a non-informative genotype in at-least one individual affected with Metachromatic Leukodystrophy, who reportedly harbored this variant (inherited from the father) along with a deletion on the other allele (Chen_2018). Based on RNA analysis, this variant was reported to impact splicing and reported as having a translational impact resulting in p.Lys125ProfsX17. However, primary evidence supporting this conclusion was not provided in this report. Neither was the identity of the exact deletion on the other allele unequivocally specified. Therefore, in our ascertainment, this report does not provide unequivocal conclusions about association of the variant with Metachromatic Leukodystrophy. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation and classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Eurofins Ntd Llc (ga)

Oct 27, 2016

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.41
CADD	Benign	19
DANN	Benign	0.82

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.97
SpliceAI score (max)		0.79		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.79		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs199476377; hg19: chr22-51065594;