NM_133642.5:c.493C>T

Variant names:

• chr22-33604557-G-A
• rs765312193
• NM_133642.5:c.493C>T

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP3

The NM_133642.5(LARGE1):​c.493C>T​(p.Arg165Trp) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000616 in 1,461,760 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R165Q) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: LARGE1 NM_133642.5 missense, splice_region
• Scores: Splicing: ADA: 0.5945
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 2.99
• Publications: 0 publications found

Genes affected

LARGE1 (HGNC:6511): (LARGE xylosyl- and glucuronyltransferase 1) This gene encodes a member of the N-acetylglucosaminyltransferase gene family. It encodes a glycosyltransferase which participates in glycosylation of alpha-dystroglycan, and may carry out the synthesis of glycoprotein and glycosphingolipid sugar chains. It may also be involved in the addition of a repeated disaccharide unit. The protein encoded by this gene is the glycotransferase that adds the final xylose and glucuronic acid to alpha-dystroglycan and thereby allows alpha-dystroglycan to bind ligands including laminin 211 and neurexin. Mutations in this gene cause several forms of congenital muscular dystrophy characterized by cognitive disability and abnormal glycosylation of alpha-dystroglycan. Alternative splicing of this gene results in multiple transcript variants that encode the same protein. [provided by RefSeq, May 2018]

LARGE1 Gene-Disease associations (from GenCC):

• muscular dystrophy-dystroglycanopathy type B6

  Inheritance: AR Classification: DEFINITIVE Submitted by: G2P
• muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A6

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp
• congenital muscular dystrophy with intellectual disability

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

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.832

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
LARGE1	NM_133642.5	c.493C>T	p.Arg165Trp	missense_variant, splice_region_variant	Exon 5 of 15	ENST00000397394.8	NP_598397.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
LARGE1	ENST00000397394.8	c.493C>T	p.Arg165Trp	missense_variant, splice_region_variant	Exon 5 of 15	5	NM_133642.5	ENSP00000380549.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461760 Hom.: 0 Cov.: 32 AF XY: 0.00000825 AC XY: 6 AN XY: 727182

African (AFR) AF: 0.00 AC: 0 AN: 33476

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

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53400

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

European-Non Finnish (NFE) AF: 0.00000719 AC: 8 AN: 1111922

Other (OTH) AF: 0.0000166 AC: 1 AN: 60392

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Muscular dystrophy-dystroglycanopathy type B6 Uncertain:1

Aug 27, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine with tryptophan at codon 165 of the LARGE1 protein (p.Arg165Trp). The arginine residue is highly conserved and there is a moderate physicochemical difference between arginine and tryptophan. This variant is present in population databases (rs765312193, ExAC 0.001%). This variant has not been reported in the literature in individuals affected with LARGE1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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. -

not provided Uncertain:1

Nov 01, 2017

CeGaT Center for Human Genetics Tuebingen

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.83
BayesDel_addAF	Uncertain	0.076	D
BayesDel_noAF	Benign	-0.13
CADD	Pathogenic	31
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.86	D;D;.
Eigen	Uncertain	0.52
Eigen_PC	Uncertain	0.50
FATHMM_MKL	Uncertain	0.86	D
LIST_S2	Uncertain	0.95	.;D;D
M_CAP	Uncertain	0.10	D
MetaRNN	Pathogenic	0.83	D;D;D
MetaSVM	Benign	-0.69	T
PhyloP100		3.0
PrimateAI	Pathogenic	0.80	T
PROVEAN	Uncertain	-4.2	D;D;D
REVEL	Uncertain	0.37
Sift	Uncertain	0.0020	D;D;D
Sift4G	Uncertain	0.0040	D;D;D
Polyphen		1.0	D;D;D
Vest4		0.85
MutPred		0.52		Loss of solvent accessibility (P = 0.0217);Loss of solvent accessibility (P = 0.0217);Loss of solvent accessibility (P = 0.0217);
MVP		0.29
MPC		1.5
ClinPred		0.99	D
GERP RS		4.7
Varity_R		0.32
gMVP		0.82
Mutation Taster		=58/42	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.59
dbscSNV1_RF	Benign	0.57
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: rs765312193; hg19: chr22-34000543; COSMIC: COSV104641786;