rs121908294

Positions:

• chr11-78112724-C-A
• chr11-78112724-C-T

Variant summary

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

The NM_024079.5(ALG8):​c.824G>T​(p.Gly275Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,166 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: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: ALG8 NM_024079.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.33

Genes affected

ALG8 (HGNC:23161): (ALG8 alpha-1,3-glucosyltransferase) This gene encodes a member of the ALG6/ALG8 glucosyltransferase family. The encoded protein catalyzes the addition of the second glucose residue to the lipid-linked oligosaccharide precursor for N-linked glycosylation of proteins. Mutations in this gene have been associated with congenital disorder of glycosylation type Ih (CDG-Ih). Alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Jul 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, 0.993

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ALG8	NM_024079.5	c.824G>T	p.Gly275Val	missense_variant	8/13	ENST00000299626.10	NP_076984.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ALG8	ENST00000299626.10	c.824G>T	p.Gly275Val	missense_variant	8/13	1	NM_024079.5	ENSP00000299626	P3

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152166 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 31

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152166 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74330

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

ALG8 congenital disorder of glycosylation Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 21, 2023

This sequence change replaces glycine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 275 of the ALG8 protein (p.Gly275Val). This variant is present in population databases (no rsID available, gnomAD 0.007%). This variant has not been reported in the literature in individuals affected with ALG8-related conditions. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt ALG8 protein function. 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	0.98
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.53
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	D;.;.;D;D;.
Eigen	Pathogenic	0.98
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.96	D;.;D;D;D;D
M_CAP	Pathogenic	0.71	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.2	H;H;H;.;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.80	T
PROVEAN	Pathogenic	-8.7	D;D;.;D;D;D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D;D;.;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;.;.;.
Polyphen		1.0	D;.;.;.;.;.
Vest4		0.98
MutPred		0.96		Loss of methylation at R274 (P = 0.114);Loss of methylation at R274 (P = 0.114);Loss of methylation at R274 (P = 0.114);.;.;.;
MVP		0.99
MPC		0.72
ClinPred		1.0	D
GERP RS		5.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.95
gMVP		0.91

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

LitVar

Other links and lift over

dbSNP: rs121908294; hg19: chr11-77823770;