22-50529325-C-T

Position:

• chr22-50529325-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_001953.5(TYMP):​c.228G>A​(p.Met76Ile) variant causes a missense change. The variant allele was found at a frequency of 0.00000479 in 1,460,972 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 Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: TYMP NM_001953.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts P:1 U:2
• Conservation: PhyloP100: 5.58

Genes affected

TYMP (HGNC:3148): (thymidine phosphorylase) This gene encodes an angiogenic factor which promotes angiogenesis in vivo and stimulates the in vitro growth of a variety of endothelial cells. It has a highly restricted target cell specificity acting only on endothelial cells. Mutations in this gene have been associated with mitochondrial neurogastrointestinal encephalomyopathy. Multiple alternatively spliced transcript variants have been identified. [provided by RefSeq, Apr 2012]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.981

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TYMP	NM_001953.5	c.228G>A	p.Met76Ile	missense_variant	3/10	ENST00000252029.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TYMP	ENST00000252029.8	c.228G>A	p.Met76Ile	missense_variant	3/10	1	NM_001953.5	P2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000401 AC: 1 AN: 249660 Hom.: 0 AF XY: 0.00000738 AC XY: 1 AN XY: 135458

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000545

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1460972 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 726820

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000450

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mitochondrial DNA depletion syndrome 1 Pathogenic:1 Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Jan 29, 2020	- -
Pathogenic, no assertion criteria provided	literature only	GeneReviews	Jan 14, 2016	- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Nov 16, 2023

Variant summary: TYMP c.228G>A (p.Met76Ile) results in a conservative amino acid change located in the Glycosyl transferase family 3, N-terminal domain (IPR017459) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 249660 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.228G>A has been reported in the literature in individuals affected with Mitochondrial DNA Depletion Syndrome 1 (MNGIE type) (Martin_2004). These data do not allow any conclusion about variant significance. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication have been ascertained in the context of this evaluation (PMID: 15505189). Two submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. One submitter classified the variant as pathogenic, and one submitter classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.40
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.77	D;.;D;D;D
Eigen	Uncertain	0.53
Eigen_PC	Uncertain	0.47
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.91	.;D;.;D;D
M_CAP	Uncertain	0.28	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D
MetaSVM	Pathogenic	0.89	D
MutationAssessor	Pathogenic	4.1	H;H;H;H;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Benign	0.46	T
PROVEAN	Uncertain	-3.5	D;D;D;D;D
REVEL	Pathogenic	0.87
Sift	Uncertain	0.019	D;D;D;D;D
Sift4G	Uncertain	0.011	D;D;D;D;D
Polyphen		0.98	D;.;D;D;.
Vest4		0.69
MutPred		0.95		Loss of MoRF binding (P = 0.0932);Loss of MoRF binding (P = 0.0932);Loss of MoRF binding (P = 0.0932);Loss of MoRF binding (P = 0.0932);Loss of MoRF binding (P = 0.0932);
MVP		0.78
MPC		1.3
ClinPred		0.92	D
GERP RS		5.0
Varity_R		0.88
gMVP		0.94

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.11		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1064792859; hg19: chr22-50967754;