NM_000388.4:c.1A>C

Variant names:

• chr3-122254190-A-C
• NM_000388.4:c.1A>C

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PVS1 PS1_Moderate PM2 PP5_Moderate

The NM_000388.4(CASR):​c.1A>C​(p.Met1?) variant causes a initiator codon 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 Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: CASR NM_000388.4 initiator_codon
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 6.28

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 Pathogenic. Variant got 14 ACMG points.

• PVS1: Start lost variant, next in-frame start position is after 20 pathogenic variants. Next in-frame start position is after 74 codons. Genomic position: 122257115. Lost 0.068 part of the original CDS.
• PS1: Another start lost variant in NM_000388.4 (CASR) was described as [Pathogenic] in Lovd
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-122254190-A-C is Pathogenic according to our data. Variant chr3-122254190-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1784165.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CASR	NM_000388.4	c.1A>C	p.Met1?	initiator_codon_variant	Exon 2 of 7	ENST00000639785.2	NP_000379.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CASR	ENST00000639785.2	c.1A>C	p.Met1?	initiator_codon_variant	Exon 2 of 7	1	NM_000388.4	ENSP00000491584.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Nephrolithiasis/nephrocalcinosis Pathogenic:1

Nov 10, 2020

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.M1? variant (also known as c.1A>C) is located in coding exon 1 of the CASR gene and results from an A to C substitution at nucleotide position 1. This alters the methionine residue at the initiation codon (ATG). This amino acid position is highly conserved in available vertebrate species. Another alteration at the same initiation codon, p.M1? (c.2T>G), has been described in a homozygous neonatal severe hyperparathyroidism case, with high normal calcium levels detected in one carrier parent (de Andrade SC et al. Clin Endocrinol (Oxf), 2006 Dec;65:826-7). In addition to the clinical data presented in the literature, sequence variations that modify the initiation codon are expected to result in either loss of translation initiation, N-terminal truncation, or cause a shift in the mRNA reading frame. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.28	D
BayesDel_noAF	Pathogenic	0.17
CADD	Benign	19
DANN	Benign	0.93
DEOGEN2	Benign	0.38	T;T;.;.
Eigen	Benign	-0.019
Eigen_PC	Benign	0.11
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.90	.;D;D;D
M_CAP	Pathogenic	0.30	D
MetaRNN	Pathogenic	0.96	D;D;D;D
MetaSVM	Uncertain	-0.13	T
PROVEAN	Benign	-0.40	.;.;N;N
REVEL	Uncertain	0.59
Sift	Benign	0.066	.;.;T;T
Sift4G	Benign	0.15	.;.;T;T
Polyphen		0.075	B;B;.;.
Vest4		0.76, 0.76
MutPred		0.84		Loss of glycosylation at S5 (P = 0.0332);Loss of glycosylation at S5 (P = 0.0332);Loss of glycosylation at S5 (P = 0.0332);Loss of glycosylation at S5 (P = 0.0332);
MVP		0.93
ClinPred		0.99	D
GERP RS		5.3
Varity_R		0.40
gMVP		0.64

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr3-121973037;