3-122257115-A-G

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP2 PP3_Strong

The NM_000388.4(CASR):c.220A>G(p.Met74Val) variant causes a missense change involving the alteration of a conserved nucleotide. 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. M74L) has been classified 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: 9.32

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 Likely_pathogenic. Variant got 9 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, 12 uncertain in NM_000388.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, CASR
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.959

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CASR	NM_000388.4	c.220A>G	p.Met74Val	missense_variant	3/7	ENST00000639785.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CASR	ENST00000639785.2	c.220A>G	p.Met74Val	missense_variant	3/7	1	NM_000388.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000254 Hom.: 0

Bravo AF: 0.00000378

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 07, 2021

This sequence change replaces methionine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 74 of the CASR protein (p.Met74Val). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with hypocalciuric hypercalcemia type 1 or primary hyperparathyroidism (PMID: 26963950, 32347971). 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: "Probably Damaging"; Align-GVGD: "Class C15"). 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	0.60
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.26
Cadd	Uncertain	26
Dann	Uncertain	0.99
DEOGEN2	Uncertain	0.77	D;D;.;.
Eigen	Pathogenic	0.76
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Uncertain	0.22	D
MetaRNN	Pathogenic	0.96	D;D;D;D
MetaSVM	Uncertain	0.025	D
MutationAssessor	Pathogenic	3.3	M;M;M;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.70	T
Polyphen		0.98	D;D;.;.
Vest4		0.97, 0.97
MutPred		0.86		Gain of MoRF binding (P = 0.1336);Gain of MoRF binding (P = 0.1336);Gain of MoRF binding (P = 0.1336);Gain of MoRF binding (P = 0.1336);
MVP		0.87
MPC		1.6
ClinPred		0.99	D
GERP RS		5.8
Varity_R		0.90
gMVP		0.98

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: rs745377913; hg19: chr3-121975962;