rs150799088
Variant summary
Our verdict is Uncertain significance. The variant received 4 ACMG points: 5P and 1B. PM1PM5PP2BP4
The NM_000478.6(ALPL):c.1349G>A(p.Arg450His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000057 in 1,613,154 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R450C) has been classified as Likely pathogenic.
Frequency
Consequence
NM_000478.6 missense
Scores
Clinical Significance
Conservation
Publications
- adult hypophosphatasiaInheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: ClinGen, PanelApp Australia, Labcorp Genetics (formerly Invitae), Orphanet
- childhood hypophosphatasiaInheritance: AR, AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: Laboratory for Molecular Medicine, ClinGen, Orphanet
- hypophosphatasiaInheritance: AR Classification: DEFINITIVE Submitted by: Myriad Women’s Health, G2P
- infantile hypophosphatasiaInheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, ClinGen, Labcorp Genetics (formerly Invitae), PanelApp Australia
- odontohypophosphatasiaInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- perinatal lethal hypophosphatasiaInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
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ACMG classification
Our verdict: Uncertain_significance. The variant received 4 ACMG points.
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| ALPL | NM_000478.6 | c.1349G>A | p.Arg450His | missense_variant | Exon 12 of 12 | ENST00000374840.8 | NP_000469.3 |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | Exon rank | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| ALPL | ENST00000374840.8 | c.1349G>A | p.Arg450His | missense_variant | Exon 12 of 12 | 1 | NM_000478.6 | ENSP00000363973.3 |
Frequencies
GnomAD3 genomes AF: 0.0000263 AC: 4AN: 152208Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.0000772 AC: 19AN: 246148 AF XY: 0.0000448 show subpopulations
GnomAD4 exome AF: 0.0000602 AC: 88AN: 1460828Hom.: 1 Cov.: 33 AF XY: 0.0000633 AC XY: 46AN XY: 726772 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000263 AC: 4AN: 152326Hom.: 0 Cov.: 32 AF XY: 0.0000403 AC XY: 3AN XY: 74480 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
not provided Uncertain:3
The ALPL: p.Arg450His variant (also reported as R433H; rs150799088) has been previously reported in a patient with odontohypophosphatasia (Taillandier 2000). The patient described in Taillandier et al (2000) also carried a second rare ALPL variant, but further inheritance information, including the phase of the two ALPL variants was not provided. Function studies of the p.Arg450His variant in cell culture could not identify an enzymatic defect (Nasu 2006), although a different variant in the same codon, p.Arg450Cys, lead to a severe disruption in enzyme function (Nasu 2006). However, the p.Arg450Cys variant has been identified as a homozygote in individuals with severe hypophosphatasia (Mornet 1988), and the function defects described in Nasu et al (2006) are likely attributable to the substituted cysteine residue. Furthermore, the p.Arg450His variant is listed in the Genome Aggregation Database (gnomAD) browser with a frequency in South Asian populations of 0.04% (identified in 13 out of 30,690 chromosomes, including 1 homozygote). Therefore, based on the available information, the clinical significance of the p.Arg450His variant cannot be determined with certainty. -
Identified in a patient with reduced alkaline phosphatase activity who also harbored a second variant (phase unknown) in published literature (Taillandier et al., 2000); Published functional studies demonstrate that this variant does not impact enzyme activity levels (Del Angel et al., 2020; Nasu et al., 2006); In silico analysis supports that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 17212778, 16769381, 32160374, 23791648, 10679946, 25023282) -
This sequence change replaces arginine, which is basic and polar, with histidine, which is basic and polar, at codon 450 of the ALPL protein (p.Arg450His). This variant is present in population databases (rs150799088, gnomAD 0.04%). This missense change has been observed in individual(s) with hypophosphatasia (PMID: 10679946). This variant is also known as R433H. ClinVar contains an entry for this variant (Variation ID: 429390). 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 ALPL protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change does not substantially affect ALPL function (PMID: 17212778, 32160374). This variant disrupts the p.Arg450 amino acid residue in ALPL. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 9781036, 17212778, 25731960, 29159075). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
Childhood hypophosphatasia;C0268412:Infantile hypophosphatasia;C0268413:Adult hypophosphatasia Uncertain:2
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Infantile hypophosphatasia Uncertain:2
This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -
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not specified Uncertain:1
Variant summary: ALPL c.1349G>A (p.Arg450His) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 7.7e-05 in 246148 control chromosomes in the gnomAD database, including 1 homozygote. This frequency is not significantly higher than estimated for a pathogenic variant in ALPL causing Hypophosphatasia (7.7e-05 vs 0.0035), allowing no conclusion about variant significance. c.1349G>A has been reported in the literature as a compound heterozygous genotype in at-least one individual affected with Odontoid Hypophosphatasia (example Taillandier_2000 cited in Del Angel_2020). These data do not allow any conclusion about variant significance. At least two publications report experimental evidence evaluating an impact on protein function (example, Nasu_2006 and Del Angel_2020). These results showed no damaging effect of this variant on ALPL activity in-vitro. Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -
Hypophosphatasia Uncertain:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at