NM_000478.6:c.818C>G

Variant names:

• chr1-21570330-C-G
• rs148405563
• NM_000478.6:c.818C>G

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_000478.6(ALPL):​c.818C>G​(p.Thr273Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,854 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict 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. T273M) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: ALPL NM_000478.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.478

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 Uncertain_significance. Variant got 2 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 uncertain in NM_000478.6
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.24490917).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ALPL	NM_000478.6	c.818C>G	p.Thr273Arg	missense_variant	Exon 8 of 12	ENST00000374840.8	NP_000469.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ALPL	ENST00000374840.8	c.818C>G	p.Thr273Arg	missense_variant	Exon 8 of 12	1	NM_000478.6	ENSP00000363973.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251362 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135872

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461854 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727228

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: 0.00

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Sep 05, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on ALPL protein function. This variant has not been reported in the literature in individuals affected with ALPL-related conditions. This variant is present in population databases (no rsID available, gnomAD 0.006%). This sequence change replaces threonine, which is neutral and polar, with arginine, which is basic and polar, at codon 273 of the ALPL protein (p.Thr273Arg). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.071
BayesDel_addAF	Benign	-0.035	T
BayesDel_noAF	Benign	-0.12
CADD	Benign	18
DANN	Benign	0.97
DEOGEN2	Pathogenic	0.82	D;.;.;D
Eigen	Benign	-0.51
Eigen_PC	Benign	-0.38
FATHMM_MKL	Benign	0.19	N
LIST_S2	Benign	0.75	.;T;T;T
M_CAP	Uncertain	0.11	D
MetaRNN	Benign	0.24	T;T;T;T
MetaSVM	Uncertain	-0.20	T
MutationAssessor	Benign	1.2	L;.;.;L
PrimateAI	Benign	0.45	T
PROVEAN	Uncertain	-2.4	N;N;N;N
REVEL	Uncertain	0.35
Sift	Benign	0.11	T;T;T;T
Sift4G	Benign	0.45	T;T;T;T
Polyphen		0.012	B;.;.;B
Vest4		0.29
MutPred		0.43		Loss of sheet (P = 0.0357);.;.;Loss of sheet (P = 0.0357);
MVP		0.87
MPC		0.47
ClinPred		0.18	T
GERP RS		4.2
Varity_R		0.14
gMVP		0.72

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.12		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: rs148405563; hg19: chr1-21896823;