3-122283867-G-T

Position:

• chr3-122283867-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PP2 PP3_Strong PP5

The NM_000388.4(CASR):​c.1913G>T​(p.Arg638Leu) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,461,682 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: CASR NM_000388.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: 6.79

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 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), CASR. . Gene score misZ 3.1237 (greater than the threshold 3.09). Trascript score misZ 4.8257 (greater than threshold 3.09). GenCC has associacion of gene with epilepsy, autosomal dominant hypocalcemia, familial hypocalciuric hypercalcemia 1, epilepsy, idiopathic generalized, susceptibility to, 8, neonatal severe primary hyperparathyroidism, autosomal dominant hypocalcemia 1.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.975
• PP5: Variant 3-122283867-G-T is Pathogenic according to our data. Variant chr3-122283867-G-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 265466.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Pathogenic=1}. Variant chr3-122283867-G-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CASR	NM_000388.4	c.1913G>T	p.Arg638Leu	missense_variant	7/7	ENST00000639785.2	NP_000379.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CASR	ENST00000639785.2	c.1913G>T	p.Arg638Leu	missense_variant	7/7	1	NM_000388.4	ENSP00000491584.2
CASR	ENST00000498619.4	c.1943G>T	p.Arg648Leu	missense_variant	7/7	1		ENSP00000420194.1
CASR	ENST00000638421.1	c.1913G>T	p.Arg638Leu	missense_variant	7/7	5		ENSP00000492190.1
CASR	ENST00000490131.7	c.1682G>T	p.Arg561Leu	missense_variant	5/5	5		ENSP00000418685.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251328 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135872

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: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461682 Hom.: 0 Cov.: 33 AF XY: 0.00000275 AC XY: 2 AN XY: 727158

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: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

May 23, 2016

The R638L missense variant in the CASR gene has been reported previously in association with calcium homeostasis disorders (D'Souza-Li et al., 2002; Corrado et al., 2015). The variant was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. R638L is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution occurs at a position that is conserved across species, and in silico analysis predicts this variant is probably damaging to the protein structure/function. Functional studies have shown that R638L prevents proper localization of the CASR protein and results in its degradation (White et al., 2009). Therefore, this variant is pathogenic. -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Jun 06, 2023

Variant summary: CASR c.1913G>T (p.Arg638Leu) results in a non-conservative amino acid change located in the C-terminal cytoplasmic domain (IPR17978) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 251328 control chromosomes( i.e. in 1 carrier) in the gnomAD database (v2.1). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. The variant, c.1913G>T, has been reported in the literature in a compound heterozygous individual affected with Neonatal Severe Hyperparathyroidism, and in heterozygous state in one of her parents, affected with Familial Hypocalciuric Hypercalcemia (Corrado_2015); in addition, the variant was also reported in a cohort of patients affected with Familial Hypocalciuric Hypercalcemia (Vargas-Poussou_2016). At least one publication reported experimental evidence evaluating an impact on protein function, and demonstrated that the variant prevented proper localization of the CASR protein at the plasma membrane, and likely resulted in its degradation in the endoplasmic reticulum (White_2009). The following publications have been ascertained in the context of this evaluation (PMID: 19389809, 26963950, 25828954). Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. One laboratory classified the variant as pathogenic, while the other laboratory classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 11, 2023

This sequence change replaces arginine, which is basic and polar, with leucine, which is neutral and non-polar, at codon 638 of the CASR protein (p.Arg638Leu). This variant is present in population databases (no rsID available, gnomAD 0.0009%). This missense change has been observed in individual(s) with familial hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism (PMID: 25828954, 26963950). ClinVar contains an entry for this variant (Variation ID: 265466). 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. Experimental studies have shown that this missense change affects CASR function (PMID: 19389809). 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	Uncertain	0.38
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.33
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.82	D;D;.;.
Eigen	Pathogenic	0.87
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.90	.;D;D;D
M_CAP	Uncertain	0.27	D
MetaRNN	Pathogenic	0.97	D;D;D;D
MetaSVM	Uncertain	0.77	D
MutationAssessor	Benign	1.6	L;L;.;.
PrimateAI	Uncertain	0.77	T
PROVEAN	Pathogenic	-4.8	.;.;D;.
REVEL	Pathogenic	0.89
Sift	Benign	0.039	.;.;D;.
Sift4G	Uncertain	0.010	.;.;D;.
Polyphen		1.0	D;D;.;.
Vest4		0.90
MutPred		0.89		.;.;Gain of ubiquitination at K646 (P = 0.0609);.;
MVP		0.97
MPC		1.7
ClinPred		0.99	D
GERP RS		5.9
Varity_R		0.71
gMVP		0.97

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: rs201852643; hg19: chr3-122002714;