1-46196784-C-G

Variant names:

• chr1-46196784-C-G
• rs150576537
• NM_017739.4:c.301G>C

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 4P and 1B. PM1 PM2 BP4

The NM_017739.4(POMGNT1):​c.301G>C​(p.Val101Leu) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,842 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/22 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V101I) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: POMGNT1 NM_017739.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 4.44
• Publications: 0 publications found

Genes affected

POMGNT1 (HGNC:19139): (protein O-linked mannose N-acetylglucosaminyltransferase 1 (beta 1,2-)) This gene encodes a type II transmembrane protein that resides in the Golgi apparatus. It participates in O-mannosyl glycosylation and is specific for alpha linked terminal mannose. Mutations in this gene may be associated with muscle-eye-brain disease and several congenital muscular dystrophies. Alternatively spliced transcript variants that encode different protein isoforms have been described. [provided by RefSeq, Feb 2014]

POMGNT1 Gene-Disease associations (from GenCC):

• autosomal recessive limb-girdle muscular dystrophy type 2O

  Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE, LIMITED Submitted by: G2P, Ambry Genetics, Orphanet
• muscle-eye-brain disease

  Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, Myriad Women’s Health
• muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A3

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P, Genomics England PanelApp
• muscular dystrophy-dystroglycanopathy (congenital with intellectual disability), type B3

  Inheritance: AR Classification: DEFINITIVE, LIMITED Submitted by: G2P, Ambry Genetics
• myopathy caused by variation in POMGNT1

  Inheritance: AR Classification: STRONG Submitted by: ClinGen
• retinitis pigmentosa 76

  Inheritance: AR Classification: STRONG, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
• retinitis pigmentosa

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

  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.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 15 uncertain in NM_017739.4
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.2909915).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
POMGNT1	NM_017739.4	c.301G>C	p.Val101Leu	missense_variant	Exon 4 of 22	ENST00000371984.8	NP_060209.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
POMGNT1	ENST00000371984.8	c.301G>C	p.Val101Leu	missense_variant	Exon 4 of 22	1	NM_017739.4	ENSP00000361052.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461842 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 727220

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

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

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

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: 53374

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112008

Other (OTH) AF: 0.0000166 AC: 1 AN: 60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.26
BayesDel_addAF	Benign	-0.035	T
BayesDel_noAF	Benign	-0.29
CADD	Benign	21
DANN	Uncertain	0.99
DEOGEN2	Benign	0.010	T;T;.
Eigen	Benign	-0.14
Eigen_PC	Benign	0.035
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.95	D;D;D
M_CAP	Benign	0.048	D
MetaRNN	Benign	0.29	T;T;T
MetaSVM	Benign	-0.72	T
MutationAssessor	Benign	0.95	.;L;L
PhyloP100		4.4
PrimateAI	Pathogenic	0.81	D
PROVEAN	Benign	-0.54	N;N;N
REVEL	Benign	0.059
Sift	Benign	0.21	T;T;T
Sift4G	Benign	0.14	T;T;T
Polyphen		0.42	B;B;.
Vest4		0.61
MutPred		0.38		Gain of catalytic residue at V101 (P = 0.0676);Gain of catalytic residue at V101 (P = 0.0676);Gain of catalytic residue at V101 (P = 0.0676);
MVP		0.68
MPC		0.24
ClinPred		0.52	D
GERP RS		5.1
Varity_R		0.36
gMVP		0.48
Mutation Taster		=88/12	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs150576537; hg19: chr1-46662456;