NM_014946.4:c.1496G>T

Variant names:

• chr2-32141906-G-T
• rs878854991
• NM_014946.4:c.1496G>T

Variant summary

Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Moderate

The NM_014946.4(SPAST):​c.1496G>T​(p.Arg499Leu) variant causes a missense, splice region 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. 13/22 in silico tools predict a damaging outcome for this variant. 1/1 splice prediction tools predict no significant impact on normal splicing. 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. R499H) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: SPAST NM_014946.4 missense, splice_region
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 8.02
• Publications: 19 publications found

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 Gene-Disease associations (from GenCC):

• hereditary spastic paraplegia 4

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Illumina, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), PanelApp Australia, Ambry Genetics, Orphanet
• Charlevoix-Saguenay spastic ataxia

  Inheritance: AR Classification: DEFINITIVE Submitted by: G2P
• neurodevelopmental disorder

  Inheritance: AD Classification: STRONG Submitted by: G2P
• SPAST-related motor disorder

  Inheritance: AR Classification: STRONG Submitted by: Ambry Genetics

ACMG classification

Our verdict: Pathogenic. The variant received 13 ACMG points.

• PM1: In a hotspot region, there are 15 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 10 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 chr2-32141906-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 240950.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 148 curated pathogenic missense variants (we use a threshold of 10). The gene has 21 curated benign missense variants. Gene score misZ: 1.2438 (below the threshold of 3.09). Trascript score misZ: 0.22274 (below the threshold of 3.09). GenCC associations: The gene is linked to hereditary spastic paraplegia 4, SPAST-related motor disorder, Charlevoix-Saguenay spastic ataxia, neurodevelopmental disorder.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 2-32141906-G-T is Pathogenic according to our data. Variant chr2-32141906-G-T is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 801664.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_014946.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SPAST	NM_014946.4	MANE Select	c.1496G>T	p.Arg499Leu	missense splice_region	Exon 13 of 17	NP_055761.2
	SPAST	NM_001363823.2		c.1493G>T	p.Arg498Leu	missense splice_region	Exon 13 of 17	NP_001350752.1	A0A2U3TZR0
	SPAST	NM_199436.2		c.1400G>T	p.Arg467Leu	missense splice_region	Exon 12 of 16	NP_955468.1	E5KRP6

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SPAST	ENST00000315285.9	TSL:1 MANE Select	c.1496G>T	p.Arg499Leu	missense splice_region	Exon 13 of 17	ENSP00000320885.3	Q9UBP0-1
	SPAST	ENST00000621856.2	TSL:1	c.1493G>T	p.Arg498Leu	missense splice_region	Exon 13 of 17	ENSP00000482496.2	A0A2U3TZR0
	SPAST	ENST00000713716.1		c.1601G>T	p.Arg534Leu	missense splice_region	Exon 14 of 18	ENSP00000519019.1	A0AAQ5BGQ0

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 6.87e-7 AC: 1 AN: 1455970 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 724242

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33210

American (AMR) AF: 0.00 AC: 0 AN: 44192

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25988

East Asian (EAS) AF: 0.00 AC: 0 AN: 39522

South Asian (SAS) AF: 0.00 AC: 0 AN: 85110

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53068

Middle Eastern (MID) AF: 0.000179 AC: 1 AN: 5582

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1109190

Other (OTH) AF: 0.00 AC: 0 AN: 60108

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
1	-	-	Hereditary spastic paraplegia 4 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.59	D
BayesDel_noAF	Pathogenic	0.61
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.94	D
Eigen	Pathogenic	0.96
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.52	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.3	H
PhyloP100		8.0
PrimateAI	Pathogenic	0.82	D
PROVEAN	Pathogenic	-6.8	D
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.97
MutPred		0.96		Loss of MoRF binding (P = 0.0183)
MVP		0.98
MPC		2.3
ClinPred		1.0	D
GERP RS		5.0
Varity_R		0.98
gMVP		0.99
Mutation Taster		=0/100	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs878854991; hg19: chr2-32366975;