3-122284234-C-G

Variant names:

• chr3-122284234-C-G
• rs1553769074
• NM_000388.4:c.2280C>G

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM1 PM2 PP2

The NM_000388.4(CASR):​c.2280C>G​(p.Ile760Met) variant causes a missense 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I760F) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: CASR NM_000388.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.59
• Publications: 0 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: Uncertain_significance. The variant received 5 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 25 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.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CASR	NM_000388.4	c.2280C>G	p.Ile760Met	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.2280C>G	p.Ile760Met	missense_variant	Exon 7 of 7	1	NM_000388.4	ENSP00000491584.2
CASR	ENST00000498619.4	c.2310C>G	p.Ile770Met	missense_variant	Exon 7 of 7	1		ENSP00000420194.1
CASR	ENST00000638421.1	c.2280C>G	p.Ile760Met	missense_variant	Exon 7 of 7	5		ENSP00000492190.1
CASR	ENST00000490131.7	c.2049C>G	p.Ile683Met	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:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Sep 03, 2018

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0"). This sequence change replaces isoleucine with methionine at codon 760 of the CASR protein (p.Ile760Met). The isoleucine residue is highly conserved and there is a small physicochemical difference between isoleucine and methionine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with CASR-related disease. 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	Benign	0.17
BayesDel_addAF	Pathogenic	0.25	D
BayesDel_noAF	Uncertain	0.13
CADD	Benign	23
DANN	Benign	0.94
DEOGEN2	Benign	0.39	T;T;.;.
Eigen	Benign	0.087
Eigen_PC	Benign	0.22
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Uncertain	0.91	.;D;D;D
M_CAP	Benign	0.032	D
MetaRNN	Uncertain	0.56	D;D;D;D
MetaSVM	Uncertain	-0.13	T
MutationAssessor	Benign	0.77	N;N;.;.
PhyloP100		2.6
PrimateAI	Uncertain	0.77	T
PROVEAN	Benign	0.33	.;.;N;.
REVEL	Uncertain	0.55
Sift	Benign	0.096	.;.;T;.
Sift4G	Benign	0.21	.;.;T;.
Polyphen		0.64	P;P;.;.
Vest4		0.73
MutPred		0.43		.;.;Gain of disorder (P = 0.074);.;
MVP		0.90
MPC		0.75
ClinPred		0.60	D
GERP RS		5.0
Varity_R		0.29
gMVP		0.50
Mutation Taster		=24/76	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: rs1553769074; hg19: chr3-122003081;