2-107992992-C-T

Position:

• chr2-107992992-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_021815.5(SLC5A7):​c.313C>T​(p.Pro105Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,826 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 Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: SLC5A7 NM_021815.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter P:1 U:2
• Conservation: PhyloP100: 7.91

Genes affected

SLC5A7 (HGNC:14025): (solute carrier family 5 member 7) This gene encodes a sodium ion- and chloride ion-dependent high-affinity transporter that mediates choline uptake for acetylcholine synthesis in cholinergic neurons. The protein transports choline from the extracellular space into presynaptic terminals for synthesis into acetylcholine. Increased choline uptake results from increased density of this protein in synaptosomal plasma membranes in response to depolarization of cholinergic terminals. Dysfunction of cholinergic signaling has been implicated in various disorders including depression, attention-deficit disorder, and schizophrenia. An allelic variant of this gene is associated with autosomal dominant distal hereditary motor neuronopathy type VIIA. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2015]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.889

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SLC5A7	NM_021815.5	c.313C>T	p.Pro105Ser	missense_variant	4/9	ENST00000264047.3	NP_068587.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SLC5A7	ENST00000264047.3	c.313C>T	p.Pro105Ser	missense_variant	4/9	1	NM_021815.5	ENSP00000264047.2
SLC5A7	ENST00000409059.5	c.313C>T	p.Pro105Ser	missense_variant	4/9	1		ENSP00000387346.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461826 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 727206

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, single submitter

Submissions by phenotype

Congenital myasthenic syndrome 20 Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Oct 07, 2016

- -

Neuronopathy, distal hereditary motor, type 7A;C4310694:Congenital myasthenic syndrome 20 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 03, 2019

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Experimental studies have shown that this missense change impairs choline uptake in vitro (PMID: 27569547). This variant has been reported along with a second variant in an individual affected with congenital myasthenic syndrome with episodic apnea (PMID: 27569547). ClinVar contains an entry for this variant (Variation ID: 265762). This variant is not present in population databases (ExAC no frequency). This sequence change replaces proline with serine at codon 105 of the SLC5A7 protein (p.Pro105Ser). The proline residue is moderately conserved and there is a moderate physicochemical difference between proline and serine. -

SLC5A7-related disorder Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Dec 22, 2023

The SLC5A7 c.313C>T variant is predicted to result in the amino acid substitution p.Pro105Ser. This variant was reported with another missense variant in an individual with autosomal recessive congenital myasthenic syndrome with episodic apnea; and in vitro functional expression studies in HEK293 cells showed that these missense variants resulted in normal protein expressions, but had significantly decreased choline uptake compared to controls (Bauché et al. 2016. PubMed ID: 27569547). This variant has not been reported in a large population database, indicating this variant is rare. Although we suspect this variant may be pathogenic, at this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.75
BayesDel_addAF	Pathogenic	0.25	D
BayesDel_noAF	Uncertain	0.13
CADD	Uncertain	25
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.43	T;T
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	.;D
M_CAP	Benign	0.075	D
MetaRNN	Pathogenic	0.89	D;D
MetaSVM	Uncertain	0.57	D
MutationAssessor	Uncertain	2.5	M;M
PrimateAI	Uncertain	0.77	T
PROVEAN	Benign	-1.6	N;N
REVEL	Uncertain	0.54
Sift	Uncertain	0.016	D;D
Sift4G	Uncertain	0.012	D;D
Polyphen		1.0	D;D
Vest4		0.91
MutPred		0.58		Gain of catalytic residue at P105 (P = 0.0067);Gain of catalytic residue at P105 (P = 0.0067);
MVP		0.98
MPC		1.9
ClinPred		0.99	D
GERP RS		6.2
Varity_R		0.65
gMVP		0.91

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: rs886039766; hg19: chr2-108609448;