1-21568212-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM1 BP4

The NM_000478.6(ALPL):c.757G>C(p.Val253Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000821 in 1,461,860 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. V253I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: ALPL NM_000478.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.0270

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 1 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain in NM_000478.6
• BP4: Computational evidence support a benign effect (MetaRNN=0.3594116).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ALPL	NM_000478.6	c.757G>C	p.Val253Leu	missense_variant	7/12	ENST00000374840.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ALPL	ENST00000374840.8	c.757G>C	p.Val253Leu	missense_variant	7/12	1	NM_000478.6	P1
ALPL	ENST00000374832.5	c.757G>C	p.Val253Leu	missense_variant	7/12	2		P1
ALPL	ENST00000540617.5	c.592G>C	p.Val198Leu	missense_variant	6/11	2
ALPL	ENST00000539907.5	c.526G>C	p.Val176Leu	missense_variant	5/10	2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251356 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135902

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461860 Hom.: 0 Cov.: 31 AF XY: 0.00000963 AC XY: 7 AN XY: 727224

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000108

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 22, 2022

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) performed at Invitae indicates that this missense variant is expected to disrupt 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 (rs151270365, gnomAD 0.0009%). This sequence change replaces valine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 253 of the ALPL protein (p.Val253Leu). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.34
BayesDel_addAF	Uncertain	0.048	T
BayesDel_noAF	Benign	-0.17
Cadd	Benign	11
Dann	Benign	0.88
DEOGEN2	Pathogenic	0.83	D;.;.;D
Eigen	Benign	-1.1
Eigen_PC	Benign	-1.2
FATHMM_MKL	Benign	0.42	N
M_CAP	Uncertain	0.085	D
MetaRNN	Benign	0.36	T;T;T;T
MetaSVM	Uncertain	0.11	D
MutationAssessor	Benign	1.4	L;.;.;L
MutationTaster	Benign	0.99	N;N;N;N;N
PrimateAI	Benign	0.32	T
PROVEAN	Benign	-1.9	N;N;N;N
REVEL	Uncertain	0.35
Sift	Uncertain	0.0070	D;T;D;D
Sift4G	Benign	0.062	T;T;T;T
Polyphen		0.073	B;.;.;B
Vest4		0.20
MutPred		0.79		Loss of helix (P = 0.079);.;.;Loss of helix (P = 0.079);
MVP		0.81
MPC		0.49
ClinPred		0.49	T
GERP RS		-3.0
Varity_R		0.32
gMVP		0.78

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: rs151270365; hg19: chr1-21894705;