NM_000487.6:c.465+1G>A
Variant summary
Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_000487.6(ARSA):c.465+1G>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000815 in 1,609,324 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 Pathogenic (★★).
Frequency
Consequence
NM_000487.6 splice_donor, intron
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Pathogenic. Variant got 18 ACMG points.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
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ARSA | NM_000487.6 | c.465+1G>A | splice_donor_variant, intron_variant | Intron 2 of 7 | ENST00000216124.10 | NP_000478.3 |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | TSL | MANE | Protein | Appris | UniProt |
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ARSA | ENST00000216124.10 | c.465+1G>A | splice_donor_variant, intron_variant | Intron 2 of 7 | 1 | NM_000487.6 | ENSP00000216124.5 |
Frequencies
GnomAD3 genomes AF: 0.000427 AC: 65AN: 152184Hom.: 0 Cov.: 33
GnomAD3 exomes AF: 0.000645 AC: 155AN: 240294Hom.: 0 AF XY: 0.000662 AC XY: 87AN XY: 131390
GnomAD4 exome AF: 0.000856 AC: 1247AN: 1457140Hom.: 0 Cov.: 33 AF XY: 0.000839 AC XY: 608AN XY: 724272
GnomAD4 genome AF: 0.000427 AC: 65AN: 152184Hom.: 0 Cov.: 33 AF XY: 0.000430 AC XY: 32AN XY: 74336
ClinVar
Submissions by phenotype
Metachromatic leukodystrophy Pathogenic:22Other:2
Variant interpretted as Pathogenic and reported on 05-17-2018 by Lab or GTR ID 26957. GenomeConnect assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. GenomeConnect staff make no attempt to reinterpret the clinical significance of the variant. -
Variant summary: The ARSA c.465+1G>A variant involves the alteration of a conserved intronic nucleotide and 5/5 splice prediction tools predict a significant impact on normal splicing, which has been functionally supported (Zlotogora_1994 and Polten_1991). This variant was found in 88/111568 control chromosomes at a frequency of 0.0007888, which does not exceed the estimated maximal expected allele frequency of a pathogenic ARSA variant (0.0027951). Multiple publications have cited the variant in homozygous and compound heterozygous affected individuals diagnosed with late-, juvenile- and adult-onset depending on the second mutation in trans. The variant of interest has been indicated to be a common founder mutation (Zlotogora_1994 and Polten_1991). In addition, multiple clinical diagnostic laboratories/reputable databases classified this variant as pathogenic. Taken together, this variant is classified as pathogenic. -
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NM_000487.5(ARSA):c.465+1G>A(aka IVS2+1G>A) is classified as pathogenic in the context of metachromatic leukodystrophy and is associated with the infantile form of this disease. Sources cited for classification include the following: PMID 1670590 and 8095918. Classification of NM_000487.5(ARSA):c.465+1G>A(aka IVS2+1G>A) is based on the following criteria: The variant is located at a canonical splice site, is expected to disrupt gene function and is reported in individuals with the relevant phenotype. Please note: this variant was assessed in the context of healthy population screening.‚Äã -
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PVS1, PS3_Moderate, PM3 -
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This variant was classified as: Pathogenic. The following ACMG criteria were applied in classifying this variant: PVS1,PS1,PM2. -
Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with metachromatic leukodystrophy (MIM#250100). (I) 0106 - This gene is associated with autosomal recessive disease. (I) 0209 - Splice site variant proven to affect splicing of the transcript with uncertain effect on protein sequence. Exact protein consequence is unknown, however analysis of patient cells showed no residual protein (PMID: 1670590). (SP) 0251 - Variant is heterozygous. (I) 0304 - Variant is present in gnomAD (v2) <0.01 for a recessive condition (168 heterozygotes, 0 homozygotes). (SP) 0505 - Abnormal splicing is predicted by in silico tools and affected nucleotide is highly conserved. (SP) 0703 - Another canonical splice site variant (c.465+2T>A) has moderate previous evidence for pathogenicity, and has been reported as likely pathogenic (ClinVar). (SP) 0801 - This variant has strong previous evidence of pathogenicity in many unrelated individuals with metachromatic leukodystrophy (ClinVar, PMID: 28923328). (SP) 1001 - Strong functional evidence supporting abnormal protein function, where homozygous patient fibroblasts had no residual protein (PMID: 1670590). (SP) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -
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This variant is also known in the literature as c.459+1G>A and IVS2+1G>A (PMID: 1670590, 18786133). This variant affects the canonical splice donor site of intron 2 and is therefore predicted to interfere with splicing and result in loss of normal protein function through either protein truncation or nonsense-mediated mRNA decay (NMD). This alteration has been previously reported as a compound heterozygous change in patients with Arylsulfatase A Deficiency (also known as metachromatic leukodystrophy (MLD)) (PMID: 1670590, 18786133, 21167507, 26462614, 9090526, 11456299, 9600244, 7825603). Functional studies indicated that this variant leads to extremely low enzymatic activity (PMID: 18786133). It is present in the heterozygous state in the gnomAD population database at a frequency of 0.062% (168/271628). It is one of the most common pathogenic variant causing early-onset (late infantile) MLD in individuals of central and western European ancestry (PMID: 1670590). Multiple splice prediction tools suggest this variant is likely to interfere with normal splicing. Based on the available evidence, the c.465+1G>A variant is classified as Pathogenic. -
This sequence change affects a donor splice site in intron 2 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). This variant is present in population databases (rs80338815, gnomAD 0.1%), and has an allele count higher than expected for a pathogenic variant. Disruption of this splice site has been observed in individuals with metachromatic leukodystrophy (PMID: 1670590, 7825603, 9090526, 9600244, 11456299, 18786133, 21167507, 26462614). ClinVar contains an entry for this variant (Variation ID: 3051). 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. -
The ARSA c.465+1G>A variant, also referred to as c.459+1G>A, has been described as one of the most common pathogenic variants for arylsulfatase A deficiency occurring in the central and western European populations (Fluharty et al. 2006). Across a selection of the available literature, the c.465+1G>A variant has been identified in at least eight homozygotes, 16 compound heterozygotes, and 25 heterozygotes with an uncharacterized second allele, giving an allele frequency ranging from 7.5% to 37% in patients with arylsulfatase A deficiency (Polten et al. 1991; Eto et al. 1993; Draghia et al. 1997; Berger et al. 1997; Lugowska et al. 2005; Biffi et al. 2008; Shukla et al. 2011). Biochemical analyses indicate that the variant is associated with no residual arylsulfatase A activity (Polten et al. 1991). The c.465+1G>A variant is reported at a frequency of 0.00132 in the European (non-Finnish) population of the Exome Aggregation Consortium. Based on the collective evidence, the c.465+1G>A variant is classified as pathogenic for arylsufatase A deficiency. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -
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The homozygous c.465+1G>A variant in ARSA was identified by our study in two siblings with metachromatic leukodystrophy. The c.465+1G>A variant in ARSA has been identified in 60 unrelated individuals with autosomal recessive metachromatic leukodystrophy (PMID: 11456299, PMID: 7825603, PMID: 9600244, PMID: 18786133, PMID: 15952986, PMID: 9096767, PMID: 9090526, PMID: 8455580, PMID: 8095918, PMID: 21167507, PMID: 7815434, PMID: 2574462, PMID: 1670590), but has been identified in 0.1% (140/121592) of European (non-Finnish) chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP ID: rs80338815). Although this variant has been seen in the general population in a heterozygous state, its frequency is not high enough to rule out a pathogenic role. This variant has also been reported in ClinVar (Variation ID: 3051) and has been interpreted as pathogenic by multiple submitters. Of these 60 affected unrelated individuals, 35 were homozygotes (PMID: 7825603, PMID: 18786133, PMID: 15952986, PMID: 8455580, PMID: 8095918, PMID: 21167507, PMID: 7815434, PMID: 2574462, PMID: 1670590), 8 were compound heterozygotes who carried pathogenic or likely pathogenic variants in trans (PMID: 9090526, ClinVar ID: 3052; PMID: 9096767, ClinVar ID: 3052, ClinVar ID: 3057; PMID: 18786133, ClinVar Variation ID: 68144, ClinVar Variation ID: 840642, ClinVar Variation ID: 68126), 11 were presumed compound heterozygotes who carried pathogenic or likely pathogenic variants in unknown phase (PMID: 1670590, PMID: 8095918, ClinVar Variation ID: 3052; PMID: 15952986, ClinVar Variation ID: 3052, ClinVar ID: 3057; PMID: 9600244, ClinVar ID: 3057), and four were compound heterozygotes who carried variants of uncertain significance in trans (PMID: 9090526, ClinVar Variation ID: 68115; PMID: 18786133, ClinVar Variation ID: 68145; PMID: 11456299, ClinVar Variation ID: 3092), which increases the likelihood that the c.465+1G>A variant is pathogenic. In vitro functional studies provide some evidence that the c.465+1G>A variant may impact protein function (PMID: 2574462, PMID: 1670590). However, these types of assays may not accurately represent biological function. This variant is located in the 5' splice region. Computational tools predict a splicing impact, though this information is not predictive enough to determine pathogenicity. Loss of function of the ARSA gene is an established disease mechanism in autosomal recessive metachromatic leukodystrophy. In summary, this variant meets criteria to be classified as pathogenic for autosomal recessive metachromatic leukodystrophy. ACMG/AMP Criteria applied: PVS1, PM3_VeryStrong, PS3_Supporting (Richards 2015). -
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not provided Pathogenic:11
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PVS1, PP5, PS3 -
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Associated with no detectable arylsulfatase A activity (Gomez-Ospina et al. 2017); Canonical splice site variant in a gene for which loss-of-function is a known mechanism of disease; Previously reported as c.459+1G>A due to the use of alternate nomenclature; This variant is associated with the following publications: (PMID: 8095918, 25525159, 1670590, 18786133, 21167507, 7815434, 9600244, 11456299, 7825603, 9090526, 28923328, 20301309, 32632536, 31589614, 31418856, 31186049, 31980526, 33385934) -
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ARSA: PM3:Very Strong, PVS1, PM2, PS3:Supporting -
PP4, PS4_moderate, PVS1 -
Metachromatic leukodystrophy, adult type Pathogenic:2
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Metachromatic leukodystrophy, juvenile type Pathogenic:1
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Inborn genetic diseases Pathogenic:1
The c.465+1G>A intronic variant results from a G to A substitution one nucleotide after coding exon 2 of the ARSA gene. Alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. This alteration (also known as c.459+1G>A) is one of the most common disease-causing mutations in patients with metachromatic leukodystrophy. In the homozygous state, this mutation is associated with the late-infantile form of disease whereas in the compound heterozygote state, its been associated with a less severe presentation (Comabella, 2001; Cesani, 2016; Draghia, 1997; Heinisch, 1995; Polten, 1991). This nucleotide position is highly conserved in available vertebrate species. Patients homozygous for this alteration were found to have extremely low ARSA enzyme activity in their peripheral mononuclear blood cells (Biffi, 2008). In silico splice site analysis predicts that this alteration will weaken the native splice donor site. Based on the available evidence, this alteration is classified as pathogenic. -
ARSA-related disorder Pathogenic:1
The ARSA c.465+1G>A variant is predicted to disrupt the GT donor site and interfere with normal splicing. This variant has been documented in both homozygous and compound heterozygous states as causative for metachromatic leukodystrophy in numerous patients (Polten et al. 1991. PubMed ID: 1670590; legacy nomenclature: c.459+1G>A, or “I allele”; Gort et al. 1999. PubMed ID: 10477432; Beerepoot et al. 2020. PubMed ID: 32632536). Functional studies support the deleterious effect of this variant (Biffi et al. 2008. PubMed ID: 18786133). This variant is reported in 0.12% of alleles in individuals of European (Non-Finnish) descent in gnomAD. Variants that disrupt the consensus splice donor site in ARSA are expected to be pathogenic. This variant is interpreted as pathogenic. -
See cases Pathogenic:1
ACMG classification criteria: PVS1, PM3 -
Neurodevelopmental disorder Pathogenic:1
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Intellectual disability Uncertain:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at