chr2-32141902-A-T

Variant names:

• chr2-32141902-A-T
• rs1218081251
• NM_014946.4:c.1494-2A>T

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_014946.4(SPAST):​c.1494-2A>T variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000689 in 1,450,712 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: SPAST NM_014946.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 7.49
• Publications: 0 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 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 9.8, offset of -49, new splice context is: cctgtcatttgctgtttcAGctt. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-32141902-A-T is Pathogenic according to our data. Variant chr2-32141902-A-T is described in ClinVar as Pathogenic. ClinVar VariationId is 1455556.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 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.1494-2A>T		splice_acceptor intron	N/A	NP_055761.2
	SPAST	NM_001363823.2		c.1491-2A>T		splice_acceptor intron	N/A	NP_001350752.1	A0A2U3TZR0
	SPAST	NM_199436.2		c.1398-2A>T		splice_acceptor intron	N/A	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.1494-2A>T		splice_acceptor intron	N/A	ENSP00000320885.3	Q9UBP0-1
	SPAST	ENST00000621856.2	TSL:1	c.1491-2A>T		splice_acceptor intron	N/A	ENSP00000482496.2	A0A2U3TZR0
	SPAST	ENST00000713716.1		c.1599-2A>T		splice_acceptor intron	N/A	ENSP00000519019.1	A0AAQ5BGQ0

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.89e-7 AC: 1 AN: 1450712 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 722052

⚠️ 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: 33090

American (AMR) AF: 0.0000228 AC: 1 AN: 43932

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25942

East Asian (EAS) AF: 0.00 AC: 0 AN: 39482

South Asian (SAS) AF: 0.00 AC: 0 AN: 84986

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52966

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5494

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1104958

Other (OTH) AF: 0.00 AC: 0 AN: 59862

⚠️ 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: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
2	-	-	Hereditary spastic paraplegia 4 (2)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.24
CADD	Pathogenic	32
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.89
FATHMM_MKL	Pathogenic	0.99	D
PhyloP100		7.5
GERP RS		5.0
Mutation Taster		=0/100	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.99		Position offset: 2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs1218081251; hg19: chr2-32366971; COSMIC: COSV59513646;