Genetic Variant ALG2:p.Arg31Gln (chr9-99221803-C-T) – ACMG Classification: Uncertain_significance (4 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2PP3_Moderate

The NM_033087.4(ALG2):c.92G>A(p.Arg31Gln) variant causes a missense change. The variant allele was found at a frequency of 0.000000692 in 1,445,512 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. R31P) has been classified as Uncertain significance.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

ALG2
NM_033087.4 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 6.87

Publications

0 publications found

Variant links:

Genes affected

ALG2 (HGNC:23159): (ALG2 alpha-1,3/1,6-mannosyltransferase) This gene encodes a member of the glycosyltransferase 1 family. The encoded protein acts as an alpha 1,3 mannosyltransferase, mannosylating Man(2)GlcNAc(2)-dolichol diphosphate and Man(1)GlcNAc(2)-dolichol diphosphate to form Man(3)GlcNAc(2)-dolichol diphosphate. Defects in this gene have been associated with congenital disorder of glycosylation type Ih (CDG-Ii). Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2008]

ALG2 Gene-Disease associations (from GenCC):

congenital myasthenic syndrome 14
Inheritance: AR Classification: STRONG, MODERATE Submitted by: PanelApp Australia, Labcorp Genetics (formerly Invitae), Genomics England PanelApp
ALG2-congenital disorder of glycosylation
Inheritance: Unknown, AR Classification: STRONG, MODERATE, SUPPORTIVE, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, G2P, PanelApp Australia, Orphanet, Ambry Genetics
congenital myasthenic syndromes with glycosylation defect
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ALG2 links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.928

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ALG2	NM_033087.4 link	c.92G>A	p.Arg31Gln	missense_variant	Exon 1 of 2	ENST00000476832.2	NP_149078.1	Q9H553-1A0A024R184
ALG2	NR_024532.2 link	n.140G>A		non_coding_transcript_exon_variant	Exon 1 of 3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ALG2	ENST00000476832.2 link	c.92G>A	p.Arg31Gln	missense_variant	Exon 1 of 2	1	NM_033087.4	ENSP00000417764.1		Q9H553-1
ALG2	ENST00000238477.5 link	n.92G>A		non_coding_transcript_exon_variant	Exon 1 of 3	2		ENSP00000432675.2		A0A0A0MTE0

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.92e-7

AC:

AN:

1445512

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

719538

show subpopulations

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

African (AFR)

AF:

0.00

AC:

AN:

33420

American (AMR)

AF:

0.00

AC:

AN:

44638

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26042

East Asian (EAS)

AF:

0.00

AC:

AN:

39664

South Asian (SAS)

AF:

0.00

AC:

AN:

86140

European-Finnish (FIN)

AF:

0.00

AC:

AN:

38484

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5660

European-Non Finnish (NFE)

AF:

9.00e-7

AC:

AN:

1111264

Other (OTH)

AF:

0.00

AC:

AN:

60200

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.375

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.41

BayesDel_addAF

Pathogenic

0.33

BayesDel_noAF

Pathogenic

0.23

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Uncertain

0.57

Eigen

Pathogenic

0.78

Eigen_PC

Pathogenic

0.68

FATHMM_MKL

Uncertain

0.94

LIST_S2

Pathogenic

0.98

M_CAP

Pathogenic

0.60

MetaRNN

Pathogenic

0.93

MetaSVM

Uncertain

0.51

MutationAssessor

Pathogenic

3.8

PhyloP100

6.9

PrimateAI

Uncertain

0.66

PROVEAN

Uncertain

-3.6

REVEL

Pathogenic

0.74

Sift

Pathogenic

0.0

Sift4G

Uncertain

0.0030

Polyphen

1.0

Vest4

0.80

MutPred

0.72

Loss of helix (P = 0.079);

MVP

0.86

MPC

0.79

ClinPred

1.0

GERP RS

4.7

PromoterAI

-0.027

Neutral

(source)

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.89

gMVP

0.87

Mutation Taster

=31/69

disease causing

(source)

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over