chr2-32137172-G-C

Position:

• chr2-32137172-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM2 PM5 PP3_Strong PP5

The NM_014946.4(SPAST):​c.1477G>C​(p.Asp493His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D493G) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SPAST NM_014946.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: 8.86

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]

SPAST (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 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, 0.988
• PP5: Variant 2-32137172-G-C is Pathogenic according to our data. Variant chr2-32137172-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 417628.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Likely_pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SPAST	NM_014946.4	c.1477G>C	p.Asp493His	missense_variant	12/17	ENST00000315285.9	NP_055761.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SPAST	ENST00000315285.9	c.1477G>C	p.Asp493His	missense_variant	12/17	1	NM_014946.4	ENSP00000320885.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary spastic paraplegia 4 Pathogenic:1 Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Apr 03, 2017	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 disruptive, but these predictions have not been confirmed by published functional studies. A different missense substitution at this codon (p.Asp493Gly) has been reported to segregate with hereditary spastic paraplegia (HSP) in a single family (PMID: 16682546), but the clinical significance of this variant is uncertain. In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a SPAST-related disease. This sequence change replaces aspartic acid with histidine at codon 493 of the SPAST protein (p.Asp493His). The aspartic acid residue is highly conserved and there is a moderate physicochemical difference between aspartic acid and histidine. -
Likely pathogenic, criteria provided, single submitter	research	TIDEX, University of British Columbia	Apr 12, 2017	There is a second alternative allele (T) as this same base pair location in this patient. -

Hereditary spastic paraplegia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Genome Diagnostics Laboratory, The Hospital for Sick Children

Jun 01, 2020

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	32
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.94	D;D;.;.;.;.;.;.
Eigen	Pathogenic	0.91
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	1.0	.;D;D;.;D;D;D;D
M_CAP	Pathogenic	0.38	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.8	H;H;.;.;.;.;.;.
PrimateAI	Pathogenic	0.80	T
PROVEAN	Pathogenic	-7.0	D;.;D;.;.;.;.;.
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D;.;D;.;.;.;.;.
Sift4G	Pathogenic	0.0010	D;D;D;.;.;.;.;.
Polyphen		1.0	D;D;.;.;.;.;.;.
Vest4		0.97
MutPred		0.95		Gain of MoRF binding (P = 0.0429);Gain of MoRF binding (P = 0.0429);.;.;.;.;.;.;
MVP		0.96
MPC		2.4
ClinPred		1.0	D
GERP RS		5.4
Varity_R		0.97
gMVP		0.95

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: rs1060499939; hg19: chr2-32362241;