2-32136608-C-T

Position:

• chr2-32136608-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_014946.4(SPAST):​c.1291C>T​(p.Arg431*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,310 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: SPAST NM_014946.4 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:11 O:2
• Conservation: PhyloP100: 2.17

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 Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-32136608-C-T is Pathogenic according to our data. Variant chr2-32136608-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 188179.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-32136608-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SPAST	NM_014946.4	c.1291C>T	p.Arg431*	stop_gained	10/17	ENST00000315285.9	NP_055761.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SPAST	ENST00000315285.9	c.1291C>T	p.Arg431*	stop_gained	10/17	1	NM_014946.4	ENSP00000320885.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461310 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727002

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:11 Other:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary spastic paraplegia 4 Pathogenic:6 Other:2

Pathogenic, criteria provided, single submitter	clinical testing	Paris Brain Institute, Inserm - ICM	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Molecular Genetics, Royal Melbourne Hospital	Mar 01, 2024	This sequence change in SPAST is a nonsense variant predicted to cause a premature stop codon, p.(Arg431*), in biologically relevant exon 10/21 leading to nonsense-mediated decay in a gene in which loss-of-function is an established disease mechanism. The highest population minor allele frequency in the population database gnomAD v4.0 is 0.00009% (1/1,111,596 alleles) in the European (non-Finnish) population, which is consistent with spastic paraplegia. This variant has been reported in multiple individuals with hereditary spastic paraplegia (PMID: 31751864, 31594988, 37144097). Based on the classification scheme RMH Modified ACMG/AMP Guidelines v1.6.1, this variant is classified as PATHOGENIC. Following criteria are met: PVS1, PM2_Supporting, PS4_Moderate -
Pathogenic, criteria provided, single submitter	clinical testing	Victorian Clinical Genetics Services, Murdoch Childrens Research Institute	Feb 02, 2022	Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0103 - Dominant negative and loss-of-function are known mechanisms of disease for this gene and are associated with spastic paraplegia 4 (MIM#182601). Multiple loss of function variants have been reported, while a dominant negative mechanism has been stipulated for a small number of missense variants (ClinVar; PMID: 30006150). (I) 0107 - This gene is associated with autosomal dominant disease. (I) 0112 - The condition associated with this gene has incomplete penetrance, but this is age-dependant and only a small proportion of individuals remain asymptomatic (PMID: 30476002). (I) 0115 - Variants in this gene are known to have variable expressivity, with variable age of onset and disease severity (PMID: 30476002). (I) 0201 - Variant is predicted to cause nonsense-mediated decay (NMD) and loss of protein (premature termination codon is located at least 54 nucleotides upstream of the final exon-exon junction). (SP) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0701 - Other NMD-predicted variants comparable to the one identified in this case have very strong previous evidence for pathogenicity. These variants have been reported many times as pathogenic and observed in individuals with hereditary spastic paraplegia (HSP) (PMID: 31751864, DECIPHER). (SP) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been reported multiple times as pathogenic, and observed in individuals with HSP (ClinVar, PMID: 31751864). (SP) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 13, 2024	This sequence change creates a premature translational stop signal (p.Arg431*) in the SPAST gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in SPAST are known to be pathogenic (PMID: 20932283). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individuals with hereditary spastic paraplegia (PMID: 10699187, 18701882, 20718791, 25454648, 29980238). ClinVar contains an entry for this variant (Variation ID: 188179). For these reasons, this variant has been classified as Pathogenic. -
not provided, no classification provided	phenotyping only	GenomeConnect - Invitae Patient Insights Network	-	Variant interpreted as Pathogenic and reported on 08-30-2019 by Invitae. GenomeConnect-Invitae Patient Insights Network assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. Registry team members make no attempt to reinterpret the clinical significance of the variant. Phenotypic details are available under supporting information. -
not provided, no classification provided	phenotyping only	GenomeConnect - Brain Gene Registry	-	Variant interpreted as Pathogenic and reported on 02-23-2021 by lab or GTR ID 239772. Assertions are reported exactly as they appear on the patient provided laboratory report. GenomeConnect does not attempt to reinterpret the variant. The IDDRC-CTSA National Brain Gene Registry (BGR) is a study funded by the U.S. National Center for Advancing Translational Sciences (NCATS) and includes 13 Intellectual and Developmental Disability Research Center (IDDRC) institutions. The study is led by Principal Investigator John Constantino MD PhD from Washington University. The BGR is a data commons of gene variants paired with subject clinical information. This database helps scientists learn more about genetic changes and their impact on the brain and behavior. Participation in the Brain Gene Registry requires participation in GenomeConnect. More information about the Brain Gene Registry can be found on the study website - https://braingeneregistry.wustl.edu/. -
Likely pathogenic, no assertion criteria provided	provider interpretation	Solve-RD Consortium	Jun 01, 2022	Variant confirmed as disease-causing by referring clinical team -
Pathogenic, criteria provided, single submitter	clinical testing	MGZ Medical Genetics Center	Jan 27, 2022	- -

not provided Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Apr 01, 2019	- -
Pathogenic, criteria provided, single submitter	clinical testing	Athena Diagnostics	May 12, 2023	This variant is expected to result in the loss of a functional protein. This variant has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). This variant has been identified in multiple unrelated individuals with clinical features associated with this gene. -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Aug 30, 2023	Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Not observed in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 20718791, 34782662, 25525159, 10699187, 29980238, 26208798, 22960362, 27084228, 25454648, 26671083, 19423133, 30489674, 27334366, 15841487, 20559269, 31227335, 32213280, 31594988, 23252998) -
Pathogenic, criteria provided, single submitter	clinical testing	Clinical Genetics Laboratory, Skane University Hospital Lund	May 27, 2022	- -

Hereditary spastic paraplegia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Genome Diagnostics Laboratory, The Hospital for Sick Children

Apr 01, 2018

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	38
DANN	Uncertain	1.0
Eigen	Pathogenic	0.69
Eigen_PC	Uncertain	0.55
FATHMM_MKL	Uncertain	0.85	D
Vest4		0.95
GERP RS		3.6

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs786204126; hg19: chr2-32361677;