3-122284592-G-C

Variant names:

• chr3-122284592-G-C
• rs763865303
• NM_000388.4:c.2638G>C

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PP2 PP3

The NM_000388.4(CASR):​c.2638G>C​(p.Ala880Pro) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic 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. A880S) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: CASR NM_000388.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 6.44
• Publications: 4 publications found

Genes affected

CASR (HGNC:1514): (calcium sensing receptor) The protein encoded by this gene is a plasma membrane G protein-coupled receptor that senses small changes in circulating calcium concentration. The encoded protein couples this information to intracellular signaling pathways that modify parathyroid hormone secretion or renal cation handling, and thus this protein plays an essential role in maintaining mineral ion homeostasis. Mutations in this gene are a cause of familial hypocalciuric hypercalcemia, neonatal severe hyperparathyroidism, and autosomal dominant hypocalcemia. [provided by RefSeq, Aug 2017]

CASR Gene-Disease associations (from GenCC):

• autosomal dominant hypocalcemia 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Illumina, ClinGen, Labcorp Genetics (formerly Invitae)
• familial hypocalciuric hypercalcemia 1

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, Illumina, Orphanet, Genomics England PanelApp
• neonatal severe primary hyperparathyroidism

  Inheritance: AR, AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, ClinGen, Labcorp Genetics (formerly Invitae)
• autosomal dominant hypocalcemia

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• epilepsy, idiopathic generalized, susceptibility to, 8

  Inheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
• epilepsy

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 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, 22 uncertain in NM_000388.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the CASR gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 114 curated pathogenic missense variants (we use a threshold of 10). The gene has 10 curated benign missense variants. Gene score misZ: 3.1237 (above the threshold of 3.09). Trascript score misZ: 4.8257 (above the threshold of 3.09). GenCC associations: The gene is linked to neonatal severe primary hyperparathyroidism, autosomal dominant hypocalcemia 1, familial hypocalciuric hypercalcemia 1, epilepsy, autosomal dominant hypocalcemia, epilepsy, idiopathic generalized, susceptibility to, 8.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.786

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CASR	NM_000388.4	c.2638G>C	p.Ala880Pro	missense_variant	Exon 7 of 7	ENST00000639785.2	NP_000379.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CASR	ENST00000639785.2	c.2638G>C	p.Ala880Pro	missense_variant	Exon 7 of 7	1	NM_000388.4	ENSP00000491584.2
CASR	ENST00000498619.4	c.2668G>C	p.Ala890Pro	missense_variant	Exon 7 of 7	1		ENSP00000420194.1
CASR	ENST00000638421.1	c.2638G>C	p.Ala880Pro	missense_variant	Exon 7 of 7	5		ENSP00000492190.1
CASR	ENST00000490131.7	c.2407G>C	p.Ala803Pro	missense_variant	Exon 5 of 5	5		ENSP00000418685.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 70

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Apr 03, 2017

Athena Diagnostics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Nephrolithiasis/nephrocalcinosis Uncertain:1

Mar 23, 2019

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.A880P variant (also known as c.2638G>C), located in coding exon 6 of the CASR gene, results from a G to C substitution at nucleotide position 2638. The alanine at codon 880 is replaced by proline, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear.

Autosomal dominant hypocalcemia 1;C1809471:Familial hypocalciuric hypercalcemia Uncertain:1

Oct 04, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with proline, which is neutral and non-polar, at codon 880 of the CASR protein (p.Ala880Pro). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with CASR-related conditions. ClinVar contains an entry for this variant (Variation ID: 446997). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. 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.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.33
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.47	T;T;.;.
Eigen	Uncertain	0.65
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.0	.;D;D;D
M_CAP	Uncertain	0.17	D
MetaRNN	Pathogenic	0.79	D;D;D;D
MetaSVM	Uncertain	0.57	D
MutationAssessor	Benign	1.8	L;L;.;.
PhyloP100		6.4
PrimateAI	Pathogenic	0.87	D
PROVEAN	Benign	0.0	.;.;N;.
REVEL	Benign	0.0
Sift	Pathogenic	0.0	.;.;D;.
Sift4G	Pathogenic	0.0	.;.;D;.
Vest4		0.0
ClinPred		0.89	D
GERP RS		5.9
Varity_R		0.59
gMVP		0.90
Mutation Taster		=13/87	disease causing

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

Other links and lift over

dbSNP: rs763865303; hg19: chr3-122003439;