rs121918001

Positions:

• chr1-21561126-C-A
• chr1-21561126-C-T

Variant summary

Our verdict is Pathogenic. Variant got 20 ACMG points: 20P and 0B. PS1_Moderate PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000478.6(ALPL):​c.211C>A​(p.Arg71Ser) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,460,638 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 (★★). Another nucleotide change resulting in same amino acid change has been previously reported as Likely pathogenicin UniProt. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R71C) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: ALPL NM_000478.6 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 5.72

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]

ACMG classification

Verdict is Pathogenic. Variant got 20 ACMG points.

• PS1: Transcript NM_000478.6 (ALPL) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in UniProt
• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain in NM_000478.6
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-21561126-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 13663.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.994
• PP5: Variant 1-21561126-C-A is Pathogenic according to our data. Variant chr1-21561126-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2676552.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-21561126-C-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ALPL	NM_000478.6	c.211C>A	p.Arg71Ser	missense_variant	4/12	ENST00000374840.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ALPL	ENST00000374840.8	c.211C>A	p.Arg71Ser	missense_variant	4/12	1	NM_000478.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1460638 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 726480

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.0000330 AC: 4

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Adult hypophosphatasia Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

Jul 30, 2023

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jun 06, 2023

For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Arg71 amino acid residue in ALPL. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 11438998, 19500388, 22397652, 25731960, 31760938). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Experimental studies have shown that this missense change affects ALPL function (PMID: 11760847). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt ALPL protein function. This missense change has been observed in individual(s) with childhood-type hypophosphatasia (PMID: 11760847). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with serine, which is neutral and polar, at codon 71 of the ALPL protein (p.Arg71Ser). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.55
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.96	D;.;D
Eigen	Pathogenic	0.78
Eigen_PC	Pathogenic	0.71
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	1.0	.;D;D
M_CAP	Pathogenic	0.66	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.3	M;.;M
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-5.6	D;D;D
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;.;D
Vest4		0.98
MutPred		0.99		Loss of methylation at R71 (P = 0.0251);.;Loss of methylation at R71 (P = 0.0251);
MVP		0.99
MPC		1.1
ClinPred		1.0	D
GERP RS		5.3
Varity_R		0.98
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs121918001; hg19: chr1-21887619;