9-131509761-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_001077365.2(POMT1):c.558G>T(p.Trp186Cys) variant causes a missense change. The variant allele was found at a frequency of 0.0000178 in 1,461,886 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 Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000018 (0 hom.)
• Consequence: POMT1 NM_001077365.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.50

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.982

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
POMT1	NM_001077365.2	c.558G>T	p.Trp186Cys	missense_variant	7/20	ENST00000402686.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
POMT1	ENST00000402686.8	c.558G>T	p.Trp186Cys	missense_variant	7/20	1	NM_001077365.2	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251496 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135922

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: 0.0000980

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000178 AC: 26 AN: 1461886 Hom.: 0 Cov.: 31 AF XY: 0.0000261 AC XY: 19 AN XY: 727246

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: 0.000301

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

May 22, 2022

This sequence change replaces tryptophan, which is neutral and slightly polar, with cysteine, which is neutral and slightly polar, at codon 186 of the POMT1 protein (p.Trp186Cys). This variant is present in population databases (rs772370177, gnomAD 0.01%). This variant has not been reported in the literature in individuals affected with POMT1-related conditions. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.82
BayesDel_addAF	Pathogenic	0.30	D
BayesDel_noAF	Pathogenic	0.40
Cadd	Pathogenic	32
Dann	Uncertain	0.99
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D;D;D;D;D;.;D;D
M_CAP	Pathogenic	0.33	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.99	D
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.58	T
PROVEAN	Pathogenic	-8.9	D;D;D;D;D;D;D;D
REVEL	Pathogenic	0.88
Sift	Pathogenic	0.0	D;D;D;D;D;D;D;D
Sift4G	Uncertain	0.0030	D;D;D;D;D;D;D;D
Polyphen		1.0	.;D;.;.;D;D;.;.
Vest4		0.57
MutPred		0.89		.;Loss of catalytic residue at L184 (P = 0.003);.;.;Loss of catalytic residue at L184 (P = 0.003);Loss of catalytic residue at L184 (P = 0.003);.;.;
MVP		0.95
MPC		1.1
ClinPred		1.0	D
GERP RS		5.6
Varity_R		0.95
gMVP		0.82

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		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: rs772370177; hg19: chr9-134385148;