rs119482082

chr9-92080044-A-C

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_006415.4(SPTLC1):c.399T>G(p.Cys133Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,788 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C133R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: SPTLC1 NM_006415.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4 O:1
• Conservation: PhyloP100: 0.551

Genes affected

SPTLC1 (HGNC:11277): (serine palmitoyltransferase long chain base subunit 1) This gene encodes a member of the class-II pyridoxal-phosphate-dependent aminotransferase family. The encoded protein is the long chain base subunit 1 of serine palmitoyltransferase. Serine palmitoyltransferase converts L-serine and palmitoyl-CoA to 3-oxosphinganine with pyridoxal 5'-phosphate and is the key enzyme in sphingolipid biosynthesis. Mutations in this gene were identified in patients with hereditary sensory neuropathy type 1. Alternatively spliced variants encoding different isoforms have been identified. Pseudogenes of this gene have been defined on chromosomes 1, 6, 10, and 13. [provided by RefSeq, Jul 2013]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr9-92080045-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 4800.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.974
• PP5: Variant 9-92080044-A-C is Pathogenic according to our data. Variant chr9-92080044-A-C is described in ClinVar as [Pathogenic]. Clinvar id is 4803.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr9-92080044-A-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SPTLC1	NM_006415.4	c.399T>G	p.Cys133Trp	missense_variant	5/15	ENST00000262554.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SPTLC1	ENST00000262554.7	c.399T>G	p.Cys133Trp	missense_variant	5/15	1	NM_006415.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461788 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727198

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neuropathy, hereditary sensory and autonomic, type 1A Pathogenic:1 Other:1

not provided, no classification provided	literature only	GeneReviews	-	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Jul 23, 2010	- -

Charcot-Marie-Tooth disease Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Molecular Genetics Laboratory, London Health Sciences Centre

-

- -

Sensorimotor neuropathy Pathogenic:1

Pathogenic, no assertion criteria provided

research

NIHR Bioresource Rare Diseases, University of Cambridge

-

- -

Hereditary sensory and autonomic neuropathy type 1 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Feb 22, 2023

This sequence change replaces cysteine, which is neutral and slightly polar, with tryptophan, which is neutral and slightly polar, at codon 133 of the SPTLC1 protein (p.Cys133Trp). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with hereditary sensory and autonomic neuropathy type 1 (HSAN1) (PMID: 11242106, 11242114, 16364956, 18018475, 22302274, 26681808). ClinVar contains an entry for this variant (Variation ID: 4803). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt SPTLC1 protein function. Experimental studies have shown that this missense change affects SPTLC1 function (PMID: 14990347, 16210380, 19132419, 19923297). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant disrupts the p.Cys133 amino acid residue in SPTLC1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 11242106, 11242114, 15546589). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.47
Cadd	Uncertain	24
Dann	Uncertain	0.99
DEOGEN2	Pathogenic	0.97	D;.
Eigen	Uncertain	0.35
Eigen_PC	Benign	0.14
FATHMM_MKL	Uncertain	0.82	D
LIST_S2	Uncertain	0.92	D;D
M_CAP	Pathogenic	0.55	D
MetaRNN	Pathogenic	0.97	D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.7	H;H
MutationTaster	Benign	1.0	A;A
PrimateAI	Pathogenic	0.82	D
PROVEAN	Pathogenic	-11	D;D
REVEL	Pathogenic	0.89
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;.
Vest4		0.82
MutPred		0.85		Loss of methylation at R136 (P = 0.0408);Loss of methylation at R136 (P = 0.0408);
MVP		0.94
MPC		1.2
ClinPred		1.0	D
GERP RS		-3.8
Varity_R		0.98
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.21		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.21		Position offset: -28

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

Publications

LitVar

Other links and lift over

dbSNP: rs119482082; hg19: chr9-94842326;