chr2-227685293-A-G

Variant names:

• chr2-227685293-A-G
• rs1055957
• NM_025243.4:c.*2104T>C

Variant summary

Our verdict is Benign. The variant received -14 ACMG points: 0P and 14B. BP4_Strong BP6_Moderate BA1

The NM_025243.4(SLC19A3):​c.*2104T>C variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0326 in 152,338 control chromosomes in the GnomAD database, including 289 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Benign (★).

• Frequency:
  • Genomes: 𝑓 0.033 (289 hom., cov: 32)
  • Exomes 𝑓: 0.010 (0 hom.)
• Consequence: SLC19A3 NM_025243.4 3_prime_UTR
• Clinical Significance: Benign criteria provided, single submitter B:1
• Conservation: PhyloP100: -0.792
• 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: Benign. The variant received -14 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-1.03).
• BP6: Variant 2-227685293-A-G is Benign according to our data. Variant chr2-227685293-A-G is described in ClinVar as [Benign]. Clinvar id is 334835.Status of the report is criteria_provided_single_submitter, 1 stars.
• BA1: GnomAd4 highest subpopulation (AFR) allele frequency at 95% confidence interval = 0.11 is higher than 0.05.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SLC19A3	NM_025243.4	c.*2104T>C		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.*2104T>C		3_prime_UTR_variant	Exon 6 of 6		NM_025243.4	ENSP00000495385.1
SLC19A3	ENST00000647113.1	n.*2583T>C		non_coding_transcript_exon_variant	Exon 4 of 4			ENSP00000494966.1
SLC19A3	ENST00000647113.1	n.*2583T>C		3_prime_UTR_variant	Exon 4 of 4			ENSP00000494966.1

Frequencies

GnomAD3 genomes AF: 0.0325 AC: 4949 AN: 152124 Hom.: 289 Cov.: 32

Gnomad AFR AF: 0.113

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0135

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000621

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00316

Gnomad NFE AF: 0.000382

Gnomad OTH AF: 0.0215

GnomAD4 exome AF: 0.0104 AC: 1 AN: 96 Hom.: 0 Cov.: 0 AF XY: 0.0152 AC XY: 1 AN XY: 66

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.250 AC: 1 AN: 4

American (AMR) AF: 0.00 AC: 0 AN: 2

Ashkenazi Jewish (ASJ) AC: 0 AN: 0

East Asian (EAS) AC: 0 AN: 0

South Asian (SAS) AC: 0 AN: 0

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 6

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 2

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 76

Other (OTH) AF: 0.00 AC: 0 AN: 6

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome AF: 0.0326 AC: 4966 AN: 152242 Hom.: 289 Cov.: 32 AF XY: 0.0309 AC XY: 2300 AN XY: 74456

African (AFR) AF: 0.113 AC: 4686 AN: 41504

American (AMR) AF: 0.0135 AC: 206 AN: 15298

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5186

South Asian (SAS) AF: 0.000414 AC: 2 AN: 4826

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10622

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

European-Non Finnish (NFE) AF: 0.000382 AC: 26 AN: 68016

Other (OTH) AF: 0.0218 AC: 46 AN: 2114

Alfa AF: 0.0238 Hom.: 15

Bravo AF: 0.0361

Asia WGS AF: 0.00606 AC: 21 AN: 3478

ClinVar

Significance: Benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

Submissions by phenotype

Biotin-responsive basal ganglia disease Benign:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Benign

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 and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-1.0
CADD	Benign	2.3
DANN	Benign	0.50
PhyloP100		-0.79

Splicing

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

Other links and lift over

dbSNP: rs1055957; hg19: chr2-228550009;