15-42389050-T-C

Variant names:

• chr15-42389050-T-C
• rs1555420652
• NM_000070.3:c.755T>C

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_000070.3(CAPN3):​c.755T>C​(p.Met252Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,882 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). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. M252V) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: CAPN3 NM_000070.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:3
• Conservation: PhyloP100: 7.94
• Publications: 0 publications found

Genes affected

CAPN3 (HGNC:1480): (calpain 3) Calpain, a heterodimer consisting of a large and a small subunit, is a major intracellular protease, although its function has not been well established. This gene encodes a muscle-specific member of the calpain large subunit family that specifically binds to titin. Mutations in this gene are associated with limb-girdle muscular dystrophies type 2A. Alternate promoters and alternative splicing result in multiple transcript variants encoding different isoforms and some variants are ubiquitously expressed. [provided by RefSeq, Jul 2008]

CAPN3 Gene-Disease associations (from GenCC):

• autosomal recessive limb-girdle muscular dystrophy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• autosomal recessive limb-girdle muscular dystrophy type 2A

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Myriad Women’s Health, Labcorp Genetics (formerly Invitae)
• muscular dystrophy, limb-girdle, autosomal dominant 4

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• muscular dystrophy, limb-girdle, autosomal dominant

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen

ENSG00000258461 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 11 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 10 uncertain in NM_000070.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-42389049-A-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 1507710.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.98
• PP5: Variant 15-42389050-T-C is Pathogenic according to our data. Variant chr15-42389050-T-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 555359.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CAPN3	NM_000070.3	c.755T>C	p.Met252Thr	missense_variant	Exon 5 of 24	ENST00000397163.8	NP_000061.1
CAPN3	NM_024344.2	c.755T>C	p.Met252Thr	missense_variant	Exon 5 of 23		NP_077320.1
CAPN3	NM_173087.2	c.755T>C	p.Met252Thr	missense_variant	Exon 5 of 21		NP_775110.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CAPN3	ENST00000397163.8	c.755T>C	p.Met252Thr	missense_variant	Exon 5 of 24	1	NM_000070.3	ENSP00000380349.3
ENSG00000258461	ENST00000495723.1	n.*551T>C		non_coding_transcript_exon_variant	Exon 9 of 26	2		ENSP00000492063.1
ENSG00000258461	ENST00000495723.1	n.*551T>C		3_prime_UTR_variant	Exon 9 of 26	2		ENSP00000492063.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000795 AC: 2 AN: 251418 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS 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: 1461882 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 727246

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000447 AC: 2 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1112008

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Autosomal recessive limb-girdle muscular dystrophy type 2A Pathogenic:1 Uncertain:1

Dec 01, 2017

Counsyl

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Dec 02, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces methionine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 252 of the CAPN3 protein (p.Met252Thr). This variant is present in population databases (no rsID available, gnomAD 0.003%). This missense change has been observed in individual(s) with autosomal recessive CAPN3-related conditions (PMID: 18854869; Invitae). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. This variant has been reported in individual(s) with autosomal dominant limb-girdle muscular dystrophy (PMID: 16141003); however, the role of the variant in this condition is currently unclear. ClinVar contains an entry for this variant (Variation ID: 555359). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt CAPN3 protein function with a positive predictive value of 80%. This variant disrupts the p.Met252 amino acid residue in CAPN3. Other variant(s) that disrupt this residue have been determined to be pathogenic (Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

not provided Pathogenic:1 Uncertain:1

Oct 01, 2023

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Identified with a second variant in an individual with limb girdle muscular dystrophy, but it is not known whether the variants occurred on the same (in cis) or on different (in trans) chromosomes (Fanin et al., 2009); Identified in an individual with limb girdle muscular dystrophy, but it is unknown whether this individual was tested for variants in other genes associated with muscular dystrophy (Piluso et al., 2005); This variant is associated with the following publications: (PMID: 18854869, 20635405, 16141003) -

Aug 18, 2022

Revvity Omics, Revvity

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not specified Uncertain:1

Jun 20, 2025

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

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: CAPN3 c.755T>C (p.Met252Thr) results in a non-conservative amino acid change located in the Peptidase C2, calpain, catalytic domain (IPR001300) of the encoded protein sequence. Algorithms developed to predict the effect of missense changes on protein structure and function all suggest that this variant is likely to be disruptive. The variant allele was found at a frequency of 8e-06 in 251418 control chromosomes. c.755T>C has been observed in individuals affected with Limb-Girdle Muscular Dystrophy (e.g., Fanin_2009, Nascimbeni_2010, Piluso_2005, internal data). In one publication, an affected individual was compound heterozygous for this variant and c.1524+1G>C and whose muscle biopsy demonstrated 5% calpain quantity (Fanin_2009). These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 18854869, 20635405, 16141003). ClinVar contains an entry for this variant (Variation ID: 555359). Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.38
CADD	Pathogenic	26
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.49	T;.;.;D
Eigen	Uncertain	0.65
Eigen_PC	Uncertain	0.66
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.95	D;D;D;D
M_CAP	Uncertain	0.25	D
MetaRNN	Pathogenic	0.98	D;D;D;D
MetaSVM	Uncertain	0.68	D
MutationAssessor	Uncertain	2.6	.;M;M;M
PhyloP100		7.9
PrimateAI	Uncertain	0.73	T
PROVEAN	Uncertain	-3.8	D;D;D;D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0020	D;D;D;D
Sift4G	Uncertain	0.0060	D;D;D;D
Polyphen		0.73, 0.38, 0.98	.;P;B;D
Vest4		0.92
MutPred		0.93		Loss of stability (P = 0.027);Loss of stability (P = 0.027);Loss of stability (P = 0.027);Loss of stability (P = 0.027);
MVP		0.97
MPC		0.63
ClinPred		0.97	D
GERP RS		5.4
Varity_R		0.94
gMVP		0.90
Mutation Taster		=1/99	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: rs1555420652; hg19: chr15-42681248;