rs1553318223

Variant names:

• chr2-32136903-A-G
• rs1553318223
• NM_014946.4:c.1348A>G

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_014946.4(SPAST):​c.1348A>G​(p.Arg450Gly) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R450S) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: SPAST NM_014946.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 4.57

Genes affected

SPAST (HGNC:11233): (spastin) This gene encodes a member of the AAA (ATPases associated with a variety of cellular activities) protein family. Members of this protein family share an ATPase domain and have roles in diverse cellular processes including membrane trafficking, intracellular motility, organelle biogenesis, protein folding, and proteolysis. The use of alternative translational initiation sites in this gene results in a single transcript variant that can produce isoforms that differ in the length of their N-terminus and which thereby differ in the efficiency of their export from the nucleus to the cytoplasm. In addition, alternative splicing results in multiple transcript variants that encode isoforms that differ in other protein regions as well. One isoform of this gene has been shown to be a microtubule-severing enzyme that regulates microtubule abundance, mobility, and plus-end distribution. Mutations in this gene cause the most frequent form of autosomal dominant spastic paraplegia 4. [provided by RefSeq, May 2018]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrnull-null-null-null is described in UniProt as null.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.982
• PP5: Variant 2-32136903-A-G is Pathogenic according to our data. Variant chr2-32136903-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 536442.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SPAST	NM_014946.4	c.1348A>G	p.Arg450Gly	missense_variant	Exon 11 of 17	ENST00000315285.9	NP_055761.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SPAST	ENST00000315285.9	c.1348A>G	p.Arg450Gly	missense_variant	Exon 11 of 17	1	NM_014946.4	ENSP00000320885.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary spastic paraplegia 4 Pathogenic:3

Feb 20, 2024

Concord Molecular Medicine Laboratory, Concord Repatriation General Hospital

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has been detected in an affected individual and segregation study on both parents confirmed the variant to be de novo. In silico analysis by REVEL suggests this variant to be damaging (REVEL: 0.898). It is located in the critical core ATPase AAA-type domain (IPR003959) and in a mutational hot spot. The variation is absent in control population (GnomAD). Another amino acid changes in the same residue location has been observed in individuals with HSP (PMID: 21546041). -

Dec 01, 2021

Greenwood Genetic Center Diagnostic Laboratories, Greenwood Genetic Center

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PM5, PM2, PM1, PP3 -

Jun 09, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Arg450 amino acid residue in SPAST. Other variant(s) that disrupt this residue have been observed in individuals with SPAST-related conditions (PMID: 21546041; Invitae), which suggests that this may be a clinically significant amino acid residue. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. 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 SPAST protein function. ClinVar contains an entry for this variant (Variation ID: 536442). This missense change has been observed in individuals with clinical features of spastic paraplegia (Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 450 of the SPAST protein (p.Arg450Gly). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.48	D
BayesDel_noAF	Pathogenic	0.45
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.93	D;D;.;.;.;.;.;.
Eigen	Uncertain	0.63
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Pathogenic	0.99	.;D;D;.;D;D;D;D
M_CAP	Pathogenic	0.69	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.90	D
MutationAssessor	Uncertain	2.3	M;M;.;.;.;.;.;.
PrimateAI	Pathogenic	0.85	D
PROVEAN	Pathogenic	-6.9	D;.;D;.;.;.;.;.
REVEL	Pathogenic	0.90
Sift	Pathogenic	0.0	D;.;D;.;.;.;.;.
Sift4G	Pathogenic	0.0	D;D;D;.;.;.;.;.
Polyphen		1.0	D;D;.;.;.;.;.;.
Vest4		0.89
MutPred		0.91		Loss of stability (P = 0.0295);Loss of stability (P = 0.0295);.;.;.;.;.;.;
MVP		0.99
MPC		2.5
ClinPred		1.0	D
GERP RS		3.1
Varity_R		0.98
gMVP		0.98

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: rs1553318223; hg19: chr2-32361972;