rs752384050

Variant names:

• chr9-131518502-C-T
• rs752384050
• NM_001077365.2:c.1330C>T

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM2 PP3_Moderate PP5

The NM_001077365.2(POMT1):​c.1330C>T​(p.Arg444Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000279 in 1,613,810 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. R444H) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000028 (0 hom.)
• Consequence: POMT1 NM_001077365.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:4
• Conservation: PhyloP100: 2.74
• Publications: 2 publications found

Genes affected

POMT1 (HGNC:9202): (protein O-mannosyltransferase 1) The protein encoded by this gene is an O-mannosyltransferase that requires interaction with the product of the POMT2 gene for enzymatic function. The encoded protein is found in the membrane of the endoplasmic reticulum. Defects in this gene are a cause of Walker-Warburg syndrome (WWS) and limb-girdle muscular dystrophy type 2K (LGMD2K). Several transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Oct 2008]

POMT1 Gene-Disease associations (from GenCC):

• muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A1

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Ambry Genetics, Laboratory for Molecular Medicine, Genomics England PanelApp
• myopathy caused by variation in POMT1

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• muscular dystrophy-dystroglycanopathy (congenital with intellectual disability), type B1

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• autosomal recessive limb-girdle muscular dystrophy type 2K

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• congenital muscular dystrophy with cerebellar involvement

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• congenital muscular dystrophy with intellectual disability

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• congenital muscular dystrophy without intellectual disability

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• muscle-eye-brain disease

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• muscular dystrophy-dystroglycanopathy, type A

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000230289 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.939
• PP5: Variant 9-131518502-C-T is Pathogenic according to our data. Variant chr9-131518502-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 538722.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001077365.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	POMT1	NM_001077365.2	MANE Select	c.1330C>T	p.Arg444Cys	missense	Exon 14 of 20	NP_001070833.1
	POMT1	NM_001353193.2		c.1396C>T	p.Arg466Cys	missense	Exon 14 of 20	NP_001340122.2
	POMT1	NM_007171.4		c.1396C>T	p.Arg466Cys	missense	Exon 14 of 20	NP_009102.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	POMT1	ENST00000402686.8	TSL:1 MANE Select	c.1330C>T	p.Arg444Cys	missense	Exon 14 of 20	ENSP00000385797.4
	POMT1	ENST00000372228.9	TSL:1	c.1396C>T	p.Arg466Cys	missense	Exon 14 of 20	ENSP00000361302.3
	POMT1	ENST00000423007.6	TSL:1	c.1387C>T	p.Arg463Cys	missense	Exon 13 of 19	ENSP00000404119.2

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 152228 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000159 AC: 4 AN: 250908 AF XY: 0.0000221

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 FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000177

Gnomad OTH exome AF: 0.000163

GnomAD4 exome AF: 0.0000281 AC: 41 AN: 1461582 Hom.: 0 Cov.: 31 AF XY: 0.0000316 AC XY: 23 AN XY: 727060

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.0000464 AC: 4 AN: 86250

European-Finnish (FIN) AF: 0.0000188 AC: 1 AN: 53186

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.0000297 AC: 33 AN: 1111960

Other (OTH) AF: 0.0000497 AC: 3 AN: 60386

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 152228 Hom.: 0 Cov.: 33 AF XY: 0.0000403 AC XY: 3 AN XY: 74370

African (AFR) AF: 0.0000241 AC: 1 AN: 41456

American (AMR) AF: 0.00 AC: 0 AN: 15278

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5206

South Asian (SAS) AF: 0.000207 AC: 1 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10616

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000294 AC: 2 AN: 68044

Other (OTH) AF: 0.00 AC: 0 AN: 2094

Alfa AF: 0.0000282 Hom.: 0

Bravo AF: 0.0000264

ExAC AF: 0.0000330 AC: 4

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:4

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:2

May 02, 2018

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

May 12, 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; Has not been previously published as pathogenic or benign to our knowledge

Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A1 Pathogenic:1

Jul 17, 2023

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Likely pathogenic. Following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with POMT1-related muscular dystrophy. (I) 0106 - This gene is associated with autosomal recessive disease. (I) 0200 - Variant is predicted to result in a missense amino acid change from arginine to cysteine. (I) 0251 - This variant is heterozygous. (I) 0304 - Variant is present in gnomAD (v2) <0.01 for a recessive condition (5 heterozygotes, 0 homozygotes). (SP) 0309 - An alternative amino acid change at the same position has been observed in gnomAD (v3) (2 heterozygotes, 0 homozygotes). (I) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools or highly conserved with a major amino acid change. (SP) 0600 - Variant is located in the annotated MIR domain (DECIPHER). (I) 0710 - Another missense variant comparable to the one identified in this case has inconclusive previous evidence for pathogenicity. p.(Arg444His) has been classified as a VUS by several clinical laboratories in ClinVar. (I) 0809 - Previous evidence of pathogenicity for this variant is inconclusive. This variant has been classified as a VUS by several clinical laboratories in ClinVar. (I) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 1102 - Strong phenotype match for this individual. (SP) 1201 - Heterozygous variant detected in trans with a second pathogenic heterozygous variant p.(Trp464Leufs*74) in a recessive disease. (SP) 1206 - This variant has been shown to be paternally inherited. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign

Walker-Warburg congenital muscular dystrophy;C1836373:Autosomal recessive limb-girdle muscular dystrophy type 2K;C5436962:Muscular dystrophy-dystroglycanopathy (congenital with intellectual disability), type B1 Uncertain:1

Aug 10, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 466 of the POMT1 protein (p.Arg466Cys). This variant is present in population databases (rs752384050, gnomAD 0.004%). This variant has not been reported in the literature in individuals affected with POMT1-related conditions. ClinVar contains an entry for this variant (Variation ID: 538722). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. 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.

POMT1-related disorder Uncertain:1

Nov 21, 2023

PreventionGenetics, part of Exact Sciences

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

The POMT1 c.1396C>T variant is predicted to result in the amino acid substitution p.Arg466Cys. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.0040% of alleles in individuals of African descent in gnomAD (http://gnomad.broadinstitute.org/variant/9-134393889-C-T). At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.16
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Pathogenic	0.20
CADD	Pathogenic	34
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.96	D
Eigen	Pathogenic	0.74
Eigen_PC	Uncertain	0.60
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Uncertain	0.15	D
MetaRNN	Pathogenic	0.94	D
MetaSVM	Pathogenic	0.88	D
MutationAssessor	Pathogenic	4.1	H
PhyloP100		2.7
PrimateAI	Uncertain	0.59	T
PROVEAN	Pathogenic	-7.2	D
REVEL	Pathogenic	0.75
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.93
MutPred		0.80		Loss of methylation at R466 (P = 0.0289)
MVP		0.97
MPC		1.0
ClinPred		1.0	D
GERP RS		4.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.86
gMVP		0.78
Mutation Taster		=58/42	polymorphism

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: rs752384050; hg19: chr9-134393889;