rs755705607

Positions:

• chr9-99221676-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The ENST00000476832.2(ALG2):​c.219C>G​(p.Asp73Glu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000213 in 1,409,948 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D73H) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: ALG2 ENST00000476832.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.10

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in ENST00000476832.2
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.754

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ALG2	NM_033087.4	c.219C>G	p.Asp73Glu	missense_variant	1/2	ENST00000476832.2	NP_149078.1
ALG2	NR_024532.2	n.267C>G		non_coding_transcript_exon_variant	1/3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ALG2	ENST00000476832.2	c.219C>G	p.Asp73Glu	missense_variant	1/2	1	NM_033087.4	ENSP00000417764	P1
ALG2	ENST00000238477.5	c.219C>G	p.Asp73Glu	missense_variant, NMD_transcript_variant	1/3	2		ENSP00000432675

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000614 AC: 1 AN: 162994 Hom.: 0 AF XY: 0.0000111 AC XY: 1 AN XY: 90340

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: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000150

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000213 AC: 3 AN: 1409948 Hom.: 0 Cov.: 32 AF XY: 0.00000430 AC XY: 3 AN XY: 698130

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000183

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.00000878 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

ALG2-congenital disorder of glycosylation;C4015597:Congenital myasthenic syndrome 14 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 30, 2016

This sequence change replaces aspartic acid with glutamic acid at codon 73 of the ALG2 protein (p.Asp73Glu). The aspartic acid residue is highly conserved and there is a small physicochemical difference between aspartic acid and glutamic acid. This variant is present in population databases (rs755705607, ExAC 0.02%) but has not been reported in the literature in individuals with a ALG2-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). In summary, this variant is a rare missense change with uncertain impact on protein function. There is no indication that it causes disease, but the available evidence is currently insufficient to prove that conclusively. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.43
BayesDel_addAF	Uncertain	0.052	T
BayesDel_noAF	Benign	-0.16
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.53	D
Eigen	Uncertain	0.60
Eigen_PC	Uncertain	0.52
FATHMM_MKL	Uncertain	0.85	D
LIST_S2	Uncertain	0.91	D
M_CAP	Pathogenic	0.46	D
MetaRNN	Pathogenic	0.75	D
MetaSVM	Uncertain	0.17	D
MutationAssessor	Pathogenic	2.9	M
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.68	T
PROVEAN	Uncertain	-2.8	D
REVEL	Uncertain	0.53
Sift	Benign	0.032	D
Sift4G	Uncertain	0.018	D
Polyphen		1.0	D
Vest4		0.52
MutPred		0.62		Gain of MoRF binding (P = 0.1598);
MVP		0.81
MPC		0.57
ClinPred		0.99	D
GERP RS		4.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.71
gMVP		0.61

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

Publications

LitVar

Other links and lift over

dbSNP: rs755705607; hg19: chr9-101983958;