rs145798311
Variant summary
Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM2PP3_StrongPP5_Very_Strong
The NM_000512.5(GALNS):c.181C>T(p.Arg61Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000205 in 1,613,014 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).
Frequency
Consequence
NM_000512.5 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Pathogenic. Variant got 14 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000394 AC: 6AN: 152216Hom.: 0 Cov.: 33
GnomAD3 exomes AF: 0.0000403 AC: 10AN: 248128Hom.: 0 AF XY: 0.0000297 AC XY: 4AN XY: 134586
GnomAD4 exome AF: 0.0000185 AC: 27AN: 1460798Hom.: 0 Cov.: 32 AF XY: 0.0000165 AC XY: 12AN XY: 726648
GnomAD4 genome AF: 0.0000394 AC: 6AN: 152216Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2AN XY: 74364
ClinVar
Submissions by phenotype
Mucopolysaccharidosis, MPS-IV-A Pathogenic:8
This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 61 of the GALNS protein (p.Arg61Trp). This variant is present in population databases (rs145798311, gnomAD 0.02%). This missense change has been observed in individual(s) with mucopolysaccharidosis type IVA (PMID: 23876334, 30797135; internal data). ClinVar contains an entry for this variant (Variation ID: 381663). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt GALNS protein function with a positive predictive value of 95%. For these reasons, this variant has been classified as Pathogenic. -
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A heterozygous missense variation in exon 2 of the GALNS gene that results in the amino acid substitution of Tryptophan for Arginine at codon 61 was detected. The observed variant c.181C>T (p.Arg61Trp) has not been reported in the 1000 genomes and a minor allele frequency of 0.004% in the gnomAD databases. The in silico prediction of the variant is disease causing by DANN, SIFT and MutationTaster2. The variant has been classified as pathogenic by Uniprot and is present in the catalytic domain of the GALNS_HUMAN protein. The reference codon is conserved across species. In summary, the variant meets our criteria to be classified as a pathogenic variant. -
The patients blood mRNA analysis demonstrated the alteration of splicing. -
The prevalence of the variant in affected individuals is significantly increased compared with the prevalence in controls (PS4_strong); very low frequency in gnomAD v2.1.1 (PM2_moderate); multiple lines of computational evidence support a deleterious effect on the gene (PP3_supporting) -
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Morquio syndrome Pathogenic:1
Variant summary: GALNS c.181C>T (p.Arg61Trp) results in a non-conservative amino acid change located in the Sulfatase, N-terminal domain (IPR000917) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-05 in 248128 control chromosomes (gnomAD). This frequency is not higher than expected for a pathogenic variant in GALNS causing Mucopolysaccharidosis Type IVA (Morquio Syndrome A) (4e-05 vs 0.002), allowing no conclusion about variant significance. c.181C>T has been reported in the literature in individuals affected with Mucopolysaccharidosis Type IVA (Morquio Syndrome A) (Tomatsu_2005, Dung_2013, Li_2019, Fang_2022). These data indicate that the variant is likely to be associated with disease. Six ClinVar submitters (evaluation after 2014) cite the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as likely pathogenic. -
GALNS-related disorder Pathogenic:1
The GALNS c.181C>T variant is predicted to result in the amino acid substitution p.Arg61Trp. This variant has been reported in the homozygous and compound heterozygous states in multiple individuals with autosomal recessive mucopolysaccharidosis IVA (see for example, Table 1, Dũng et al. 2013. PubMed ID: 23876334; Table S1, Yi et al. 2022. PubMed ID: 35212421; Table 2, Fang et al. 2022. PubMed ID: 34813777). This variant is documented in 0.016% of alleles in individuals of African descent in gnomAD. This variant is interpreted as likely pathogenic. -
not provided Pathogenic:1
The R61W variant in the GALNS gene has been reported previously in mucopolysaccharidosis type IVA (MPS IVA) in an affected individual who was compound heterozygous for the R61W variant and another pathogenic variant (Tomatsu et al., 2005). Structural analysis of the R61W variant described it as a solvent-exposed hydrophobic residue, which is expected to be associated with an attenuated phenotype (Rivera-Colon et al., 2012). The R61W variant was not observed at any significant frequency in approximately 6500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. The R61W variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution occurs at a position that is not conserved. In silico analysis predicts this variant is probably damaging to the protein structure/function. Missense variants in nearby residues (D60N, D60E, G66R) have been reported in the Human Gene Mutation Database in association with MPS IVA (Stenson et al., 2014), supporting the functional importance of this region of the protein. The R61W variant is a strong candidate for a pathogenic variant. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at