NM_020919.4:c.1641G>T

Variant names:

• chr2-201753242-C-A
• rs34122078
• NM_020919.4:c.1641G>T

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_020919.4(ALS2):​c.1641G>T​(p.Arg547Ser) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,290 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. R547R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ALS2 NM_020919.4 missense, splice_region
• Scores: Splicing: ADA: 0.9990
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.22
• Publications: 0 publications found

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]

ALS2 Gene-Disease associations (from GenCC):

• ALS2-related motor neuron disease

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• amyotrophic lateral sclerosis type 2, juvenile

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp
• infantile-onset ascending hereditary spastic paralysis

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Orphanet
• juvenile primary lateral sclerosis

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Orphanet
• juvenile amyotrophic lateral sclerosis

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 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 1 benign, 4 uncertain in NM_020919.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ALS2	NM_020919.4	c.1641G>T	p.Arg547Ser	missense_variant, splice_region_variant	Exon 7 of 34	ENST00000264276.11	NP_065970.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ALS2	ENST00000264276.11	c.1641G>T	p.Arg547Ser	missense_variant, splice_region_variant	Exon 7 of 34	1	NM_020919.4	ENSP00000264276.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461290 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726964

African (AFR) AF: 0.00 AC: 0 AN: 33460

American (AMR) AF: 0.00 AC: 0 AN: 44708

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.00 AC: 0 AN: 39682

South Asian (SAS) AF: 0.00 AC: 0 AN: 86246

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53386

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 9.00e-7 AC: 1 AN: 1111548

Other (OTH) AF: 0.00 AC: 0 AN: 60366

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.11
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.67	D
Eigen	Uncertain	0.27
Eigen_PC	Uncertain	0.27
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Uncertain	0.93	D
M_CAP	Uncertain	0.16	D
MetaRNN	Pathogenic	0.83	D
MetaSVM	Uncertain	0.14	D
MutationAssessor	Benign	1.1	L
PhyloP100		1.2
PrimateAI	Uncertain	0.70	T
PROVEAN	Uncertain	-3.4	D
REVEL	Uncertain	0.60
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.0030	D
Polyphen		1.0	D
Vest4		0.83
MutPred		0.48		Gain of relative solvent accessibility (P = 0.0479);
MVP		0.90
MPC		0.90
ClinPred		0.99	D
GERP RS		3.9
Varity_R		0.84
gMVP		0.82
Mutation Taster		=47/53	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.090		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs34122078; hg19: chr2-202617965;