chr9-128566795-C-T

Position:

• chr9-128566795-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PP2 PP3 PP5

The NM_001130438.3(SPTAN1):​c.55C>T​(p.Arg19Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 32)
• Consequence: SPTAN1 NM_001130438.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:8 U:1
• Conservation: PhyloP100: 1.47

Genes affected

SPTAN1 (HGNC:11273): (spectrin alpha, non-erythrocytic 1) Spectrins are a family of filamentous cytoskeletal proteins that function as essential scaffold proteins that stabilize the plasma membrane and organize intracellular organelles. Spectrins are composed of alpha and beta dimers that associate to form tetramers linked in a head-to-head arrangement. This gene encodes an alpha spectrin that is specifically expressed in nonerythrocytic cells. The encoded protein has been implicated in other cellular functions including DNA repair and cell cycle regulation. Mutations in this gene are the cause of early infantile epileptic encephalopathy-5. Alternate splicing results in multiple transcript variants.[provided by RefSeq, Sep 2010]

SPTAN1 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), SPTAN1. . Gene score misZ 5.523 (greater than the threshold 3.09). Trascript score misZ 7.9287 (greater than threshold 3.09). GenCC has associacion of gene with developmental and epileptic encephalopathy, 5, developmental and epileptic encephalopathy, West syndrome.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.757
• PP5: Variant 9-128566795-C-T is Pathogenic according to our data. Variant chr9-128566795-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 427111.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Pathogenic=6}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SPTAN1	NM_001130438.3	c.55C>T	p.Arg19Trp	missense_variant	2/57	ENST00000372739.7	NP_001123910.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SPTAN1	ENST00000372739.7	c.55C>T	p.Arg19Trp	missense_variant	2/57	1	NM_001130438.3	ENSP00000361824.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:8 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Spastic paraplegia 91, autosomal dominant, with or without cerebellar ataxia Pathogenic:3

Pathogenic, no assertion criteria provided	literature only	OMIM	Nov 08, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Laboratory of Medical Genetics, National & Kapodistrian University of Athens	Nov 02, 2023	PS4, PM2, PP2, PP5 - The variant has been reported in ClinVar as Pathogenic by other laboratories (Variation ID 427111). This variant has been previously reported as causative for epileptic encephalopathy, spasticp araplegia and ataxia. (PMID:36331550, 35150594). -
Pathogenic, criteria provided, single submitter	clinical testing	Institute of Human Genetics, University of Leipzig Medical Center	Dec 22, 2023	Criteria applied: PS4,PS2_MOD,PS3_SUP,PM2_SUP,PP1,PP2 -

SPTAN1-related disorder Pathogenic:2

Pathogenic, no assertion criteria provided	clinical testing	PreventionGenetics, part of Exact Sciences	Jul 12, 2024	The SPTAN1 c.55C>T variant is predicted to result in the amino acid substitution p.Arg19Trp. This variant has been reported to be de novo and to segregate with disease in multiple individuals and families with spastic paraplegia (Van de Vondel et al. 2022. PubMed ID: 35150594; Table S1, Kaplanis et al. 2020. PubMed ID: 33057194; Supplemental Data 3, Zhou et al. 2022. PubMed ID: 35982159; Morsy et al. 2022. PubMed ID: 36331550). Functional studies suggest this variant disrupts protein function (Morsy et al. 2022. PubMed ID: 36331550). This variant has not been reported in a large population database, indicating this variant is rare. This variant is interpreted as pathogenic. -
Pathogenic, criteria provided, single submitter	research	Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL)	Apr 27, 2023	- -

not provided Pathogenic:1 Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Nov 01, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Aug 29, 2024	Identified in multiple individuals with a neuromuscular phenotype previously tested a GeneDx, including multiple de novo cases with confirmed parentage; 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; This variant is associated with the following publications: (PMID: 36331550, 35150594, 38168508, 35982159, 33057194) -

Early infantile epileptic encephalopathy with suppression bursts Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 19, 2023

This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 19 of the SPTAN1 protein (p.Arg19Trp). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with SPTAN1-related conditions (PMID: 35150594). In at least one individual the variant was observed to be de novo. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 427111). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on SPTAN1 protein function. For these reasons, this variant has been classified as Pathogenic. -

Hereditary spastic paraplegia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Jul 17, 2023

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 in this gene and are associated with developmental and epileptic encephalopathy 5 (MIM#613477) and hereditary spastic paraplegia MONDO:0019064, SPTAN1-related. Loss of function variants have been reported for both conditions (PMID: 35150594). (I) 0107 - This gene is associated with autosomal dominant disease. (I) 0115 - Variants in this gene are known to have variable expressivity. Intrafamilial variability has been described (PMID: 32811770, PMID: 31332438). (I) 0200 - Variant is predicted to result in a missense amino acid change from arginine to tryptophan. (I) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools or highly conserved with a major amino acid change. (SP) 0600 - Variant is located in the annotated tetramerization domain (PMID: 36331550). (I) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been reported as a VUS, but more recently as pathogenic and observed in many individuals with pure or complex hereditary spastic paraplegia. In some individuals, the variant was de novo (ClinVar, PMID: 36331550, PMID: 35150594). (SP) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
CADD	Uncertain	24
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.82	D;.;T;.;.;T;.
Eigen	Uncertain	0.63
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Pathogenic	1.0	D;D;D;D;D;D;D
M_CAP	Uncertain	0.13	D
MetaRNN	Pathogenic	0.76	D;D;D;D;D;D;D
MetaSVM	Benign	-0.44	T
MutationAssessor	Pathogenic	3.1	M;.;.;M;M;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-7.0	D;.;.;D;D;.;.
REVEL	Uncertain	0.35
Sift	Pathogenic	0.0	D;.;.;D;D;.;.
Sift4G	Pathogenic	0.0	D;D;D;D;D;.;D
Polyphen		1.0	D;.;.;D;D;.;.
Vest4		0.75
MutPred		0.40		Loss of disorder (P = 0);Loss of disorder (P = 0);.;Loss of disorder (P = 0);Loss of disorder (P = 0);Loss of disorder (P = 0);Loss of disorder (P = 0);
MVP		0.54
MPC		1.9
ClinPred		1.0	D
GERP RS		3.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.88
gMVP		0.79

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

Publications

LitVar

Other links and lift over

dbSNP: rs748232676; hg19: chr9-131329074;