20-765401-G-T

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM2PM5PP3_ModeratePP5

The NM_033409.4(SLC52A3):c.374C>A(p.Thr125Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000644 in 1,613,978 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. T125I) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.000039 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000067 ( 0 hom. )

Consequence

SLC52A3
NM_033409.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:3

Conservation

PhyloP100: 9.91

Publications

5 publications found

Variant links:

Genes affected

SLC52A3 (HGNC:16187): (solute carrier family 52 member 3) This gene encodes a riboflavin transporter protein that is strongly expressed in the intestine and likely plays a role in intestinal absorption of riboflavin. The protein is predicted to have eleven transmembrane domains and a cell surface localization signal in the C-terminus. Mutations at this locus have been associated with Brown-Vialetto-Van Laere syndrome and Fazio-Londe disease. [provided by RefSeq, Mar 2012]

SLC52A3 Gene-Disease associations (from GenCC):

Brown-Vialetto-van Laere syndrome 1
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, G2P, ClinGen, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), PanelApp Australia
progressive bulbar palsy
Inheritance: AR Classification: MODERATE Submitted by: Ambry Genetics

SLC52A3 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

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

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr20-765401-G-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2583157.Status of the report is criteria_provided_single_submitter, 1 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.871

PP5

Variant 20-765401-G-T is Pathogenic according to our data. Variant chr20-765401-G-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 1338936.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SLC52A3	NM_033409.4 link	c.374C>A	p.Thr125Asn	missense_variant	Exon 2 of 5	ENST00000645534.1	NP_212134.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SLC52A3	ENST00000645534.1 link	c.374C>A	p.Thr125Asn	missense_variant	Exon 2 of 5		NM_033409.4	ENSP00000494193.1

Frequencies

GnomAD3 genomes

AF:

0.0000394

AC:

AN:

152174

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000882

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000199

AC:

AN:

250912

AF XY:

0.0000295

show subpopulations

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:

0.0000441

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000670

AC:

AN:

1461804

Hom.:

Cov.:

AF XY:

0.0000743

AC XY:

AN XY:

727194

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53404

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.0000836

AC:

AN:

1111956

Other (OTH)

AF:

0.0000828

AC:

AN:

60386

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.474

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000394

AC:

AN:

152174

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74338

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41428

American (AMR)

AF:

0.00

AC:

AN:

15280

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5198

South Asian (SAS)

AF:

0.00

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10614

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000882

AC:

AN:

68030

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.517

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000579

Hom.:

Bravo

AF:

0.0000264

ExAC

AF:

0.00000824

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:3

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Pathogenic:1

Apr 30, 2025

GeneDx

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 29053833, 29961494, 34395718, 34662687, 37116404, 38974615) -

not specified

Uncertain:1

May 06, 2024

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: C20orf54 c.374C>A (p.Thr125Asn) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 2.8e-05 in 282314 control chromosomes. c.374C>A has been reported in the literature in individuals affected with Brown-Vialetto Laere Syndrome 1/ riboflavin transporter deficiency (e.g. Manole_2017, Chaya_2017, Frederick_2021, Elks_2023) . These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 29053833, 29961494, 34395718, 37116404). ClinVar contains an entry for this variant (Variation ID: 1338936). Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

Inborn genetic diseases

Uncertain:1

Oct 20, 2022

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.374C>A (p.T125N) alteration is located in exon 2 (coding exon 1) of the SLC52A3 gene. This alteration results from a C to A substitution at nucleotide position 374, causing the threonine (T) at amino acid position 125 to be replaced by an asparagine (N). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Brown-Vialetto-van Laere syndrome 1

Uncertain:1

May 05, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces threonine, which is neutral and polar, with asparagine, which is neutral and polar, at codon 125 of the SLC52A3 protein (p.Thr125Asn). This variant is present in population databases (rs767263985, gnomAD 0.006%). This missense change has been observed in individual(s) with Brown-Vialetto-Van Laere syndrome (PMID: 29053833). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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

Uncertain

0.53

BayesDel_addAF

Uncertain

0.075

BayesDel_noAF

Uncertain

0.0

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.32

T;T;.;T;T

Eigen

Pathogenic

0.93

Eigen_PC

Pathogenic

0.90

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.96

.;.;D;.;D

M_CAP

Uncertain

0.28

MetaRNN

Pathogenic

0.87

D;D;D;D;D

MetaSVM

Uncertain

0.79

MutationAssessor

Pathogenic

3.4

M;M;M;M;M

PhyloP100

9.9

PrimateAI

Uncertain

0.68

PROVEAN

Uncertain

-3.9

.;.;D;D;.

REVEL

Pathogenic

0.74

Sift

Uncertain

0.0070

.;.;D;D;.

Sift4G

Uncertain

0.0080

.;D;D;D;.

Polyphen

1.0

D;D;D;D;D

Vest4

0.93, 0.93

MVP

0.90

MPC

1.1

ClinPred

0.82

GERP RS

5.5

PromoterAI

0.016

Neutral

(source)

Varity_R

0.59

gMVP

0.93

Mutation Taster

=9/91

disease causing (ClinVar)

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over