2-227698738-C-G

Variant names:

• chr2-227698738-C-G
• rs747823282
• NM_025243.4:c.977G>C

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM1 PM2

The NM_025243.4(SLC19A3):​c.977G>C​(p.Gly326Ala) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. 3/3 splice prediction tools predict no significant impact on normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G326V) has been classified as Uncertain significance. The gene SLC19A3 is included in the ClinGen Criteria Specification Registry.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SLC19A3 NM_025243.4 missense, splice_region
• Scores: Splicing: ADA: 0.2913
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 4.06
• 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: Orphanet, PanelApp Australia, G2P, Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• 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

Specifications for SLC19A3 are available in the ClinGen Criteria Specification Registry and recommended for reference when assigning criteria.

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 10 uncertain in NM_025243.4
• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_025243.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SLC19A3	NM_025243.4	MANE Select	c.977G>C	p.Gly326Ala	missense splice_region	Exon 3 of 6	NP_079519.1	Q9BZV2
	SLC19A3	NM_001371411.1		c.977G>C	p.Gly326Ala	missense splice_region	Exon 3 of 6	NP_001358340.1	Q9BZV2
	SLC19A3	NM_001371412.1		c.977G>C	p.Gly326Ala	missense splice_region	Exon 3 of 6	NP_001358341.1	Q9BZV2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SLC19A3	ENST00000644224.2	MANE Select	c.977G>C	p.Gly326Ala	missense splice_region	Exon 3 of 6	ENSP00000495385.1	Q9BZV2
	SLC19A3	ENST00000258403.8	TSL:1	c.977G>C	p.Gly326Ala	missense splice_region	Exon 3 of 6	ENSP00000258403.3	Q9BZV2
	SLC19A3	ENST00000425817.6	TSL:1	n.*1002G>C		splice_region non_coding_transcript_exon	Exon 5 of 8	ENSP00000397393.2	E7EM61

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000227

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.091
BayesDel_addAF	Uncertain	0.051	T
BayesDel_noAF	Benign	-0.16
CADD	Benign	18
DANN	Uncertain	1.0
DEOGEN2	Benign	0.11	T
Eigen	Uncertain	0.43
Eigen_PC	Uncertain	0.43
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.91	D
M_CAP	Benign	0.078	D
MetaRNN	Uncertain	0.58	D
MetaSVM	Uncertain	0.24	D
MutationAssessor	Uncertain	2.7	M
PhyloP100		4.1
PrimateAI	Benign	0.39	T
PROVEAN	Benign	0.40	N
REVEL	Uncertain	0.43
Sift	Benign	0.25	T
Sift4G	Benign	0.35	T
Polyphen		0.77	P
Vest4		0.31
MutPred		0.58		Loss of catalytic residue at G327 (P = 0.1851)
MVP		0.94
MPC		0.30
ClinPred		0.86	D
GERP RS		4.9
Varity_R		0.069
gMVP		0.32
Mutation Taster		=84/16	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.29
dbscSNV1_RF	Benign	0.48
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: rs747823282; hg19: chr2-228563454;