chr16-5072040-C-T

Position:

• chr16-5072040-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_019109.5(ALG1):​c.191C>T​(p.Thr64Ile) variant causes a missense change. The variant allele was found at a frequency of 0.00000139 in 1,436,550 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. T64N) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: ALG1 NM_019109.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.87

Genes affected

ALG1 (HGNC:18294): (ALG1 chitobiosyldiphosphodolichol beta-mannosyltransferase) The enzyme encoded by this gene catalyzes the first mannosylation step in the biosynthesis of lipid-linked oligosaccharides. This gene is mutated in congenital disorder of glycosylation type Ik. [provided by RefSeq, Dec 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ALG1	NM_019109.5	c.191C>T	p.Thr64Ile	missense_variant	1/13	ENST00000262374.10
ALG1	XM_017023457.3	c.191C>T	p.Thr64Ile	missense_variant	1/12
ALG1	XR_007064892.1	n.198C>T		non_coding_transcript_exon_variant	1/10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ALG1	ENST00000262374.10	c.191C>T	p.Thr64Ile	missense_variant	1/13	1	NM_019109.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000139 AC: 2 AN: 1436550 Hom.: 0 Cov.: 31 AF XY: 0.00000140 AC XY: 1 AN XY: 712360

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: 9.10e-7

Gnomad4 OTH exome AF: 0.0000168

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

ALG1-congenital disorder of glycosylation Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 01, 2021

This sequence change replaces threonine with isoleucine at codon 64 of the ALG1 protein (p.Thr64Ile). The threonine residue is moderately conserved and there is a moderate physicochemical difference between threonine and isoleucine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with ALG1-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 ALG1 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	Uncertain	0.45
BayesDel_addAF	Pathogenic	0.21	D
BayesDel_noAF	Uncertain	0.060
CADD	Uncertain	26
DANN	Uncertain	0.99
DEOGEN2	Benign	0.36	T;T
Eigen	Uncertain	0.36
Eigen_PC	Uncertain	0.37
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.83	T;T
M_CAP	Uncertain	0.20	D
MetaRNN	Uncertain	0.70	D;D
MetaSVM	Uncertain	0.0054	D
MutationAssessor	Uncertain	2.7	M;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.56	T
PROVEAN	Uncertain	-2.9	D;.
REVEL	Uncertain	0.60
Sift	Uncertain	0.029	D;.
Sift4G	Benign	0.13	T;T
Polyphen		0.90	P;.
Vest4		0.61
MutPred		0.48		Gain of sheet (P = 0.1451);Gain of sheet (P = 0.1451);
MVP		0.87
MPC		0.094
ClinPred		0.98	D
GERP RS		4.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0
Varity_R		0.20
gMVP		0.72

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.12		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: rs145474820; hg19: chr16-5122041;