chr2-32154375-T-G

Position:

• chr2-32154375-T-G

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PM5 PP3 PP5

The NM_014946.4(SPAST):​c.1730T>G​(p.Met577Arg) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. 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. M577T) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SPAST NM_014946.4 missense, splice_region
• Scores: Splicing: ADA: 0.3350
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 5.65

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 4 uncertain in NM_014946.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-32154375-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 3256959.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.768
• PP5: Variant 2-32154375-T-G is Pathogenic according to our data. Variant chr2-32154375-T-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 448450.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=2, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SPAST	NM_014946.4	c.1730T>G	p.Met577Arg	missense_variant, splice_region_variant	17/17	ENST00000315285.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SPAST	ENST00000315285.9	c.1730T>G	p.Met577Arg	missense_variant, splice_region_variant	17/17	1	NM_014946.4	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1 Uncertain:1

Likely pathogenic, criteria provided, single submitter	clinical testing	Athena Diagnostics	Jul 26, 2016	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	May 10, 2023	Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 21139634, 26094131) -

Hereditary spastic paraplegia 4 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 21, 2023

This sequence change replaces methionine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 577 of the SPAST protein (p.Met577Arg). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with hereditary spastic paraplegia (Invitae). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 448450). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant  is likely to be tolerated. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

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	0.99
DEOGEN2	Uncertain	0.65	D;D;.;.;.;.;.;.
Eigen	Uncertain	0.52
Eigen_PC	Uncertain	0.57
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.93	.;D;D;.;D;D;D;D
M_CAP	Pathogenic	0.48	D
MetaRNN	Pathogenic	0.77	D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Benign	1.3	L;L;.;.;.;.;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.90	D
PROVEAN	Pathogenic	-4.6	D;.;D;.;.;.;.;.
REVEL	Pathogenic	0.80
Sift	Uncertain	0.0010	D;.;D;.;.;.;.;.
Sift4G	Uncertain	0.0030	D;D;D;.;.;.;.;.
Polyphen		0.95	P;P;.;.;.;.;.;.
Vest4		0.76
MutPred		0.43		Gain of MoRF binding (P = 0.0186);Gain of MoRF binding (P = 0.0186);.;.;.;.;.;.;
MVP		0.94
MPC		2.0
ClinPred		0.98	D
GERP RS		5.6
Varity_R		0.92
gMVP		0.93

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.34
dbscSNV1_RF	Benign	0.39
SpliceAI score (max)		0.14		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: rs1553321196; hg19: chr2-32379444;