chr3-122262016-C-G

Variant names:

• chr3-122262016-C-G
• rs1240483254
• NM_000388.4:c.981C>G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP2

The NM_000388.4(CASR):​c.981C>G​(p.Ile327Met) 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 (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: CASR NM_000388.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.261

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• 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 epilepsy, autosomal dominant hypocalcemia, familial hypocalciuric hypercalcemia 1, epilepsy, idiopathic generalized, susceptibility to, 8, neonatal severe primary hyperparathyroidism, autosomal dominant hypocalcemia 1.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CASR	NM_000388.4	c.981C>G	p.Ile327Met	missense_variant	Exon 4 of 7	ENST00000639785.2	NP_000379.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CASR	ENST00000639785.2	c.981C>G	p.Ile327Met	missense_variant	Exon 4 of 7	1	NM_000388.4	ENSP00000491584.2
CASR	ENST00000498619.4	c.981C>G	p.Ile327Met	missense_variant	Exon 4 of 7	1		ENSP00000420194.1
CASR	ENST00000638421.1	c.981C>G	p.Ile327Met	missense_variant	Exon 4 of 7	5		ENSP00000492190.1
CASR	ENST00000490131.7	c.981C>G	p.Ile327Met	missense_variant	Exon 3 of 5	5		ENSP00000418685.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 32

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

Nov 04, 2018

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces isoleucine with methionine at codon 327 of the CASR protein (p.Ile327Met). 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) and has not been reported in the literature in individuals with a CASR-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.16
BayesDel_addAF	Pathogenic	0.26	D
BayesDel_noAF	Pathogenic	0.14
CADD	Benign	20
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.75	D;D;.;.
Eigen	Uncertain	0.29
Eigen_PC	Uncertain	0.26
FATHMM_MKL	Uncertain	0.85	D
LIST_S2	Uncertain	0.93	.;D;D;D
M_CAP	Uncertain	0.11	D
MetaRNN	Uncertain	0.74	D;D;D;D
MetaSVM	Uncertain	0.12	D
MutationAssessor	Uncertain	2.2	M;M;M;.
PrimateAI	Uncertain	0.77	T
PROVEAN	Uncertain	-2.6	.;.;D;D
REVEL	Pathogenic	0.68
Sift	Benign	0.045	.;.;D;D
Sift4G	Uncertain	0.039	.;.;D;D
Polyphen		0.89	P;P;.;.
Vest4		0.83, 0.84
MutPred		0.70		Loss of catalytic residue at I327 (P = 0.0057);Loss of catalytic residue at I327 (P = 0.0057);Loss of catalytic residue at I327 (P = 0.0057);Loss of catalytic residue at I327 (P = 0.0057);
MVP		0.92
MPC		1.5
ClinPred		0.89	D
GERP RS		1.9
Varity_R		0.74
gMVP		0.87

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: rs1240483254; hg19: chr3-121980863;