NM_025243.4:c.1154T>G

Variant names:

• chr2-227695907-A-C
• rs563607795
• NM_025243.4:c.1154T>G

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM2 PP3_Strong PP5

The NM_025243.4(SLC19A3):​c.1154T>G​(p.Leu385Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000889 in 1,461,848 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L385P) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000089 (0 hom.)
• Consequence: SLC19A3 NM_025243.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 8.86
• Publications: 6 publications found

Genes affected

SLC19A3 (HGNC:16266): (solute carrier family 19 member 3) This gene encodes a ubiquitously expressed transmembrane thiamine transporter that lacks folate transport activity. Mutations in this gene cause biotin-responsive basal ganglia disease (BBGD); a recessive disorder manifested in childhood that progresses to chronic encephalopathy, dystonia, quadriparesis, and death if untreated. Patients with BBGD have bilateral necrosis in the head of the caudate nucleus and in the putamen. Administration of high doses of biotin in the early progression of the disorder eliminates pathological symptoms while delayed treatment results in residual paraparesis, mild cognitive disability, or dystonia. Administration of thiamine is ineffective in the treatment of this disorder. Experiments have failed to show that this protein can transport biotin. Mutations in this gene also cause a Wernicke's-like encephalopathy.[provided by RefSeq, Jan 2010]

SLC19A3 Gene-Disease associations (from GenCC):

• biotin-responsive basal ganglia disease

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, Genomics England PanelApp, G2P
• Leigh syndrome

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• infantile spams-psychomotor retardation-progressive brain atrophy-basal ganglia disease syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• Leigh syndrome with leukodystrophy

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• thiamine-responsive encephalopathy

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.943
• PP5: Variant 2-227695907-A-C is Pathogenic according to our data. Variant chr2-227695907-A-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 215161.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SLC19A3	NM_025243.4	c.1154T>G	p.Leu385Arg	missense_variant	Exon 4 of 6	ENST00000644224.2	NP_079519.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SLC19A3	ENST00000644224.2	c.1154T>G	p.Leu385Arg	missense_variant	Exon 4 of 6		NM_025243.4	ENSP00000495385.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.0000119 AC: 3 AN: 251482 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000264

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000889 AC: 13 AN: 1461848 Hom.: 0 Cov.: 30 AF XY: 0.00000825 AC XY: 6 AN XY: 727230

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5736

European-Non Finnish (NFE) AF: 0.0000117 AC: 13 AN: 1112006

Other (OTH) AF: 0.00 AC: 0 AN: 60392

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000138 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Biotin-responsive basal ganglia disease Pathogenic:1 Uncertain:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The SLC19A3 c.1154T>G (p.Leu385Arg) variant has been reported in one study in which it is found in seven patients with an unidentified leukoencephalopathy including three patients in a homozygous state and four patients in a presumed compound heterozygous state (Kevelam et al. 2013). The variant was absent from 13,000 control chromosomes and is reported at a frequency of 0.00002 in the European (non-Finnish) population of the Exome Aggregation Consortium. This frequency is based on one allele in an area of good coverage so the variant is presumed to be rare. Based on the evidence, the p.Leu385Arg variant is classified as pathogenic for thiamine metabolism dysfunction syndrome. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Mar 19, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces leucine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 385 of the SLC19A3 protein (p.Leu385Arg). This variant is present in population databases (rs563607795, gnomAD 0.003%). This missense change has been observed in individual(s) with SLC19A3-related conditions (PMID: 23482991). ClinVar contains an entry for this variant (Variation ID: 215161). 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 SLC19A3 protein function. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.70
BayesDel_addAF	Pathogenic	0.43	D
BayesDel_noAF	Pathogenic	0.45
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.79	D;D;.
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.92	.;D;D
M_CAP	Pathogenic	0.50	D
MetaRNN	Pathogenic	0.94	D;D;D
MetaSVM	Pathogenic	0.87	D
MutationAssessor	Pathogenic	3.4	M;M;.
PhyloP100		8.9
PrimateAI	Uncertain	0.60	T
PROVEAN	Pathogenic	-5.3	.;D;.
REVEL	Pathogenic	0.95
Sift	Uncertain	0.0010	.;D;.
Sift4G	Uncertain	0.0040	.;D;.
Polyphen		1.0	D;D;.
Vest4		0.98
MutPred		0.79		Loss of stability (P = 0.0123);Loss of stability (P = 0.0123);.;
MVP		0.95
MPC		0.43
ClinPred		0.99	D
GERP RS		5.0
Varity_R		0.92
gMVP		0.61
Mutation Taster		=37/63	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs563607795; hg19: chr2-228560623; COSMIC: COSV99296086; COSMIC: COSV99296086;