2-227685579-A-T

Variant names:

• chr2-227685579-A-T
• rs189430957
• NM_025243.4:c.*1818T>A

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 0P and 4B. BP4_Strong

The NM_025243.4(SLC19A3):​c.*1818T>A variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000131 in 152,194 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.00013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: SLC19A3 NM_025243.4 3_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.847
• Publications: 0 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_benign. The variant received -4 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.94).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SLC19A3	NM_025243.4	c.*1818T>A		3_prime_UTR_variant	Exon 6 of 6	ENST00000644224.2	NP_079519.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SLC19A3	ENST00000644224.2	c.*1818T>A		3_prime_UTR_variant	Exon 6 of 6		NM_025243.4	ENSP00000495385.1
SLC19A3	ENST00000647113.1	n.*2297T>A		non_coding_transcript_exon_variant	Exon 4 of 4			ENSP00000494966.1
SLC19A3	ENST00000647113.1	n.*2297T>A		3_prime_UTR_variant	Exon 4 of 4			ENSP00000494966.1
SLC19A3	ENST00000676066.1	n.*101T>A		downstream_gene_variant

Frequencies

GnomAD3 genomes AF: 0.000132 AC: 20 AN: 152076 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00116

Gnomad SAS AF: 0.000623

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000132

Gnomad OTH AF: 0.000479

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 28 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 14

African (AFR) AC: 0 AN: 0

American (AMR) AC: 0 AN: 0

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 2

East Asian (EAS) AC: 0 AN: 0

South Asian (SAS) AC: 0 AN: 0

European-Finnish (FIN) AC: 0 AN: 0

Middle Eastern (MID) AC: 0 AN: 0

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 22

Other (OTH) AF: 0.00 AC: 0 AN: 4

GnomAD4 genome AF: 0.000131 AC: 20 AN: 152194 Hom.: 0 Cov.: 32 AF XY: 0.000108 AC XY: 8 AN XY: 74404

African (AFR) AF: 0.00 AC: 0 AN: 41532

American (AMR) AF: 0.0000654 AC: 1 AN: 15292

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00116 AC: 6 AN: 5172

South Asian (SAS) AF: 0.000624 AC: 3 AN: 4810

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10598

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.000132 AC: 9 AN: 68008

Other (OTH) AF: 0.000474 AC: 1 AN: 2108

Alfa AF: 0.000216 Hom.: 0

Bravo AF: 0.000144

Asia WGS AF: 0.00260 AC: 9 AN: 3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Biotin-responsive basal ganglia disease Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.94
CADD	Benign	0.36
DANN	Benign	0.27
PhyloP100		-0.85

Splicing

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

Other links and lift over

dbSNP: rs189430957; hg19: chr2-228550295; COSMIC: COSV51454480; COSMIC: COSV51454480;