1-42930765-C-T

Position:

• chr1-42930765-C-T

Variant summary

Our verdict is Pathogenic. Variant got 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_006516.4(SLC2A1):​c.377G>A​(p.Arg126His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000138 in 1,453,260 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 13/21 in silico tools predict a damaging outcome for this variant. 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. R126L) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: SLC2A1 NM_006516.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:9 O:1
• Conservation: PhyloP100: 7.91

Genes affected

SLC2A1 (HGNC:11005): (solute carrier family 2 member 1) This gene encodes a major glucose transporter in the mammalian blood-brain barrier. The encoded protein is found primarily in the cell membrane and on the cell surface, where it can also function as a receptor for human T-cell leukemia virus (HTLV) I and II. Mutations in this gene have been found in a family with paroxysmal exertion-induced dyskinesia. [provided by RefSeq, Apr 2013]

ACMG classification

Verdict is Pathogenic. Variant got 19 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 8 uncertain in NM_006516.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-42930766-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 16118.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), SLC2A1. . Gene score misZ: 2.9256 (greater than the threshold 3.09). Trascript score misZ: 4.6729 (greater than threshold 3.09). The gene has 98 curated pathogenic missense variants (we use a threshold of 10). The gene has 7 curated benign missense variants. GenCC has associacion of the gene with childhood absence epilepsy, dystonia 9, epilepsy, idiopathic generalized, susceptibility to, 12, GLUT1 deficiency syndrome, myoclonic-astatic epilepsy, childhood onset GLUT1 deficiency syndrome 2, hereditary cryohydrocytosis with reduced stomatin, encephalopathy due to GLUT1 deficiency.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.992
• PP5: Variant 1-42930765-C-T is Pathogenic according to our data. Variant chr1-42930765-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 16111.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-42930765-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SLC2A1	NM_006516.4	c.377G>A	p.Arg126His	missense_variant	4/10	ENST00000426263.10	NP_006507.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SLC2A1	ENST00000426263.10	c.377G>A	p.Arg126His	missense_variant	4/10	1	NM_006516.4	ENSP00000416293.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000138 AC: 2 AN: 1453260 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 723380

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: 0.0000445

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:9 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Encephalopathy due to GLUT1 deficiency Pathogenic:3 Other:1

Pathogenic, no assertion criteria provided	literature only	OMIM	Oct 01, 2001	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Feb 08, 2013	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Apr 11, 2023	- -
not provided, no classification provided	literature only	GeneReviews	-	- -

not provided Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Jun 01, 2018	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Jul 13, 2023	Published functional studies suggest that the R126H variant results in reduced glucose update (Brockmann et al., 2001; Jiang et al., 2010); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 12181017, 18387950, 21069159, 17052934, 24847886, 20574033, 15622525, 29530121, 32005694, 31175295, 34992632, 11603379, 19798636, 12325075) -
Pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Mar 12, 2013	- -

Childhood onset GLUT1 deficiency syndrome 2 Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	MGZ Medical Genetics Center	Jun 27, 2022	- -
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: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with SLC2A1-related disease (OMIM). (I) 0108 - This gene is associated with both recessive and dominant disease. Most individuals have autosomal dominant disease, but rare cases are described with an autosomal recessive mode of inheritance (PMID: 31196579). (I) 0112 - The condition associated with this gene has incomplete penetrance. Incomplete penetrance has been reported in families with GLUT1 deficiency syndrome or epilepsy, who were heterozygous for pathogenic missense variants (OMIM, PMID: 18451999). (I) 0115 - Variants in this gene are known to have variable expressivity (PMID: 20129935). (I) 0200 - Variant is predicted to result in a missense amino acid change from arginine to histidine. (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 sugar transporter domain (DECIPHER). (I) 0702 - Other missense variants comparable to the one identified in this case have strong previous evidence for pathogenicity. p.(Arg1267Cys) has been classified as pathogenic or likely pathogenic by several clinical laboratories in ClinVar, p.(Arg126Gly) has been classified as pathogenic in a VCGS internal patient, and p.(Arg126Leu) has been reported as de novo, in a compound heterozygous state in a patient who inherited another missense variant from an asymptomatic mother. The compound heterozygous patient had a more severe phenotype than patients with the heterozygous p.(Arg126Cys) or p.(Arg126His) variants. (PMID: 20687207). (SP) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been classified as pathogenic or likely pathogenic by multiple clinical laboratories in ClinVar, and has been reported in at least one individual and one family with autosomal dominant Glut 1 deficiency in the literature (PMIDs: 34541019, 11603379). (SP) 1002 - This variant has moderate functional evidence supporting abnormal protein function. This variant has been shown to significantly decrease glucose transport compared to wild type when tranfected into X. Laevis oocytes (PMID: 11603379). (SP) 1206 - This variant has been shown to be paternally inherited (by trio analysis). (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

GLUT1 deficiency syndrome 1, autosomal recessive Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 17, 2022

For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Arg126 amino acid residue in SLC2A1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 17718830, 19798636, 21546317, 26193382). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Experimental studies have shown that this missense change affects SLC2A1 function (PMID: 11603379). 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 SLC2A1 protein function. ClinVar contains an entry for this variant (Variation ID: 16111). This missense change has been observed in individuals with glucose transporter type 1 (GLUT1) deficiency (PMID: 11603379, 29530121). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with histidine, which is basic and polar, at codon 126 of the SLC2A1 protein (p.Arg126His). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.93
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.47
CADD	Pathogenic	34
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.97	D;.
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.91	D;D
M_CAP	Pathogenic	0.65	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.7	H;.
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-4.7	D;.
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	D;.
Sift4G	Pathogenic	0.0010	D;D
Polyphen		1.0	D;.
Vest4		0.99
MutPred		0.98		Loss of methylation at R126 (P = 0.0505);.;
MVP		0.99
MPC		2.2
ClinPred		1.0	D
GERP RS		5.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.97
gMVP		0.98

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: rs80359816; hg19: chr1-43396436;