18-669174-G-A

Position:

• chr18-669174-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_001071.4(TYMS):​c.556+1G>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,514 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TYMS NM_001071.4 splice_donor, intron
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.44

Genes affected

TYMS (HGNC:12441): (thymidylate synthetase) Thymidylate synthase catalyzes the methylation of deoxyuridylate to deoxythymidylate using, 10-methylenetetrahydrofolate (methylene-THF) as a cofactor. This function maintains the dTMP (thymidine-5-prime monophosphate) pool critical for DNA replication and repair. The enzyme has been of interest as a target for cancer chemotherapeutic agents. It is considered to be the primary site of action for 5-fluorouracil, 5-fluoro-2-prime-deoxyuridine, and some folate analogs. Expression of this gene and that of a naturally occurring antisense transcript, mitochondrial enolase superfamily member 1 (GeneID:55556), vary inversely when cell-growth progresses from late-log to plateau phase. Polymorphisms in this gene may be associated with etiology of neoplasia, including breast cancer, and response to chemotherapy. [provided by RefSeq, Aug 2017]

ENOSF1 (HGNC:30365): (enolase superfamily member 1) This gene can encode a mitochondrial enzyme that is thought to convert L-fuconate to 2-keto-3-deoxy-L-fuconate. This locus was originally identified as the source of antisense RNAs of the adjacent thymidylate synthase gene. Splice variants at this locus may contain an alternate 3' exon that is complementary to the 3'UTR and terminal intron of the thymidylate synthase (TS) RNA and may downregulate TS expression. [provided by RefSeq, Aug 2017]

TYMS (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.10721868 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 18-669174-G-A is Pathogenic according to our data. Variant chr18-669174-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 1693539.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr18-669174-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TYMS	NM_001071.4	c.556+1G>A		splice_donor_variant, intron_variant		ENST00000323274.15	NP_001062.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TYMS	ENST00000323274.15	c.556+1G>A		splice_donor_variant, intron_variant		1	NM_001071.4	ENSP00000315644.10

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461514 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727094

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Dyskeratosis congenita Pathogenic:1

Pathogenic, criteria provided, single submitter

research

Bone Marrow Failure laboratory, Queen Mary University London

Jun 22, 2022

This heterozygous splice-donor variant of TYMS was identified in a 4-year old male with dyskeratosis congenita. The following ACMG/AMP criteria were used: PVS1, PM2_supporting, PP3 -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.29	D
BayesDel_noAF	Pathogenic	0.17
CADD	Pathogenic	27
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.93
FATHMM_MKL	Pathogenic	0.99	D
GERP RS		5.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Benign	0.17
SpliceAI score (max)		0.78		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.78		Position offset: -1

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr18-669174;