3-53225857-G-A

Variant names:

• chr3-53225857-G-A
• rs370465126
• NM_001064.4:c.1771C>T

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PM2 BP4

The NM_001064.4(TKT):​c.1771C>T​(p.Arg591Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000867 in 1,613,974 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R591Q) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: TKT NM_001064.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.27
• Publications: 2 publications found

Genes affected

TKT (HGNC:11834): (transketolase) This gene encodes a thiamine-dependent enzyme which plays a role in the channeling of excess sugar phosphates to glycolysis in the pentose phosphate pathway. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene. [provided by RefSeq, Apr 2012]

TKT Gene-Disease associations (from GenCC):

• transketolase deficiency

  Inheritance: AR Classification: STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.40973467).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TKT	NM_001064.4	c.1771C>T	p.Arg591Trp	missense_variant	Exon 14 of 14	ENST00000462138.6	NP_001055.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TKT	ENST00000462138.6	c.1771C>T	p.Arg591Trp	missense_variant	Exon 14 of 14	1	NM_001064.4	ENSP00000417773.1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152134 Hom.: 0 Cov.: 32

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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000796 AC: 2 AN: 251308 AF XY: 0.00000736

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461840 Hom.: 0 Cov.: 32 AF XY: 0.00000825 AC XY: 6 AN XY: 727226

African (AFR) AF: 0.0000299 AC: 1 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44722

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

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39700

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86250

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

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 0.00000809 AC: 9 AN: 1111982

Other (OTH) AF: 0.00 AC: 0 AN: 60388

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152134 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74314

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

African (AFR) AF: 0.00 AC: 0 AN: 41420

American (AMR) AF: 0.00 AC: 0 AN: 15276

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5180

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10610

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000294 AC: 2 AN: 68028

Other (OTH) AF: 0.00 AC: 0 AN: 2090

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

TwinsUK AF: 0.00 AC: 0

ALSPAC AF: 0.000259 AC: 1

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000233 AC: 2

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Nov 10, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1771C>T (p.R591W) alteration is located in exon 14 (coding exon 14) of the TKT gene. This alteration results from a C to T substitution at nucleotide position 1771, causing the arginine (R) at amino acid position 591 to be replaced by a tryptophan (W). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.19
BayesDel_addAF	Benign	-0.15	T
BayesDel_noAF	Benign	-0.27
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.85	D;D;.;T
Eigen	Benign	-0.24
Eigen_PC	Benign	-0.39
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Pathogenic	0.98	.;D;D;D
M_CAP	Uncertain	0.11	D
MetaRNN	Benign	0.41	T;T;T;T
MetaSVM	Benign	-0.44	T
MutationAssessor	Benign	1.9	L;L;.;.
PhyloP100		3.3
PrimateAI	Benign	0.21	T
PROVEAN	Uncertain	-3.1	D;D;D;.
REVEL	Uncertain	0.33
Sift	Uncertain	0.0080	D;D;D;.
Sift4G	Uncertain	0.010	D;D;D;D
Polyphen		0.99	D;D;.;.
Vest4		0.18
MVP		0.85
MPC		0.95
ClinPred		0.83	D
GERP RS		0.16
RBP_binding_hub_radar		0.97
RBP_regulation_power_radar		2.7
Varity_R		0.33
gMVP		0.70
Mutation Taster		=69/31	polymorphism

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: rs370465126; hg19: chr3-53259873; COSMIC: COSV56246185; COSMIC: COSV56246185;