rs1057516230

Variant names:

• chr1-21554123-TACTA-T
• rs1057516230
• NM_000478.6:c.46_49delAACT

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000478.6(ALPL):​c.46_49delAACT​(p.Asn16ProfsTer2) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: ALPL NM_000478.6 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 1.33

Genes affected

ALPL (HGNC:438): (alkaline phosphatase, biomineralization associated) This gene encodes a member of the alkaline phosphatase family of proteins. There are at least four distinct but related alkaline phosphatases: intestinal, placental, placental-like, and liver/bone/kidney (tissue non-specific). The first three are located together on chromosome 2, while the tissue non-specific form is located on chromosome 1. The product of this gene is a membrane bound glycosylated enzyme that is not expressed in any particular tissue and is, therefore, referred to as the tissue-nonspecific form of the enzyme. Alternative splicing results in multiple transcript variants, at least one of which encodes a preproprotein that is proteolytically processed to generate the mature enzyme. This enzyme may play a role in bone mineralization. Mutations in this gene have been linked to hypophosphatasia, a disorder that is characterized by hypercalcemia and skeletal defects. [provided by RefSeq, Oct 2015]

ENSG00000289715 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 733 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-21554123-TACTA-T is Pathogenic according to our data. Variant chr1-21554123-TACTA-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 370095.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-21554123-TACTA-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ALPL	NM_000478.6	c.46_49delAACT	p.Asn16ProfsTer2	frameshift_variant	Exon 2 of 12	ENST00000374840.8	NP_000469.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ALPL	ENST00000374840.8	c.46_49delAACT	p.Asn16ProfsTer2	frameshift_variant	Exon 2 of 12	1	NM_000478.6	ENSP00000363973.3
ENSG00000289715	ENST00000696766.1	c.*122_*125delACTA		downstream_gene_variant				ENSP00000512858.1

Frequencies

GnomAD3 genomes Cov.: 31

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Mar 15, 2016

Center for Personalized Medicine, Children's Hospital Los Angeles

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jun 05, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Asn16Profs*2) in the ALPL gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in ALPL are known to be pathogenic (PMID: 3174660, 10679946, 32973344, 33814268). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with hypophosphatasia and/or skeletal dysplasia (PMID: 24100244, 30755392). This variant is also known as c.43_46delACTA. ClinVar contains an entry for this variant (Variation ID: 370095). For these reasons, this variant has been classified as Pathogenic. -

Infantile hypophosphatasia Pathogenic:1

Nov 20, 2015

Counsyl

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hypophosphatasia Pathogenic:1

Aug 10, 2020

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: ALPL c.46_49delAACT (p.Asn16ProfsX2) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory. The variant was absent in 251480 control chromosomes. c.46_49delAACT has been reported in the literature in individuals affected with Hypophosphatasia (example, Ji_2019, de Roo_2014). To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Two 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 pathogenic (n=1)/likely pathogenic(n=1). Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1057516230; hg19: chr1-21880616;