2-201733377-T-C

Variant names:

• chr2-201733377-T-C
• NM_020919.4:c.2479A>G

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_020919.4(ALS2):​c.2479A>G​(p.Thr827Ala) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 16/21 in silico tools predict a benign 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. T827S) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: ALS2 NM_020919.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.651

Genes affected

ALS2 (HGNC:443): (alsin Rho guanine nucleotide exchange factor ALS2) The protein encoded by this gene contains an ATS1/RCC1-like domain, a RhoGEF domain, and a vacuolar protein sorting 9 (VPS9) domain, all of which are guanine-nucleotide exchange factors that activate members of the Ras superfamily of GTPases. The protein functions as a guanine nucleotide exchange factor for the small GTPase RAB5. The protein localizes with RAB5 on early endosomal compartments, and functions as a modulator for endosomal dynamics. Mutations in this gene result in several forms of juvenile lateral sclerosis and infantile-onset ascending spastic paralysis. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2008]

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.060507208).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ALS2	NM_020919.4	c.2479A>G	p.Thr827Ala	missense_variant	Exon 13 of 34	ENST00000264276.11	NP_065970.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ALS2	ENST00000264276.11	c.2479A>G	p.Thr827Ala	missense_variant	Exon 13 of 34	1	NM_020919.4	ENSP00000264276.6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Infantile-onset ascending hereditary spastic paralysis Uncertain:1

Jun 08, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine with alanine at codon 827 of the ALS2 protein (p.Thr827Ala). The threonine residue is weakly conserved and there is a small physicochemical difference between threonine and alanine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with ALS2-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. 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	Benign	0.073
BayesDel_addAF	Benign	-0.14	T
BayesDel_noAF	Benign	-0.45
CADD	Benign	18
DANN	Benign	0.85
DEOGEN2	Benign	0.088	T
Eigen	Benign	-0.55
Eigen_PC	Benign	-0.33
FATHMM_MKL	Benign	0.38	N
LIST_S2	Benign	0.75	T
M_CAP	Benign	0.0083	T
MetaRNN	Benign	0.061	T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	-0.34	N
PrimateAI	Benign	0.32	T
PROVEAN	Benign	-0.50	N
REVEL	Benign	0.089
Sift	Benign	0.55	T
Sift4G	Benign	0.51	T
Polyphen		0.0	B
Vest4		0.056
MutPred		0.31		Gain of catalytic residue at Q828 (P = 0.1206);
MVP		0.60
MPC		0.23
ClinPred		0.058	T
GERP RS		4.0
Varity_R		0.026
gMVP		0.052

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr2-202598100;