chr14-20295764-G-A

Position:

• chr14-20295764-G-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_138376.3(TTC5):​c.787C>T​(p.Arg263*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000547 in 1,461,756 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 Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000055 (0 hom.)
• Consequence: TTC5 NM_138376.3 stop_gained
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 2.85

Genes affected

TTC5 (HGNC:19274): (tetratricopeptide repeat domain 5) Predicted to enable DNA binding activity and chromatin binding activity. Predicted to be involved in DNA repair. Predicted to act upstream of or within positive regulation of transcription by RNA polymerase II. Located in nucleoplasm. [provided by Alliance of Genome Resources, Apr 2022]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 14-20295764-G-A is Pathogenic according to our data. Variant chr14-20295764-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1048623.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr14-20295764-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTC5	NM_138376.3	c.787C>T	p.Arg263*	stop_gained	7/10	ENST00000258821.8	NP_612385.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTC5	ENST00000258821.8	c.787C>T	p.Arg263*	stop_gained	7/10	1	NM_138376.3	ENSP00000258821.3
TTC5	ENST00000383029.7	n.*332C>T		non_coding_transcript_exon_variant	7/10	1		ENSP00000372496.3
TTC5	ENST00000383029.7	n.*332C>T		3_prime_UTR_variant	7/10	1		ENSP00000372496.3
TTC5	ENST00000554157.5	n.798C>T		non_coding_transcript_exon_variant	7/9	2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000797 AC: 2 AN: 251092 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135842

Gnomad AFR exome AF: 0.0000620

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000547 AC: 8 AN: 1461756 Hom.: 0 Cov.: 34 AF XY: 0.00000688 AC XY: 5 AN XY: 727204

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: 0.00000630

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neurodevelopmental disorder with cerebral atrophy and variable facial dysmorphism Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Lifecell International Pvt. Ltd	-	A Homozygote nonsense variant c.787C>T in Exon 7 of the TTC5 gene that results in the amino acid substitution p.Arg263* was identified. The observed variant has a minor allele frequency of 0.00001% in gnomAD exomes and genomes, respectively. The severity of the impact of this variant on the protein is high, based on the effect of the protein and REVEL score. Rare Exome Variant Ensemble Learner (REVEL) is an ensembl method for predicting the pathogenicity of missense variants based on a combination of scores from 13 individual tools: MutPred, FATHMM v2.3, VEST 3.0, PolyPhen-2, SIFT, PROVEAN, MutationAssessor, MutationTaster, LRT, GERP++, SiPhy, phyloP, and phastCons. The REVEL score for an individual missense variant can range from 0 to 1, with higher scores reflecting greater likelihood that the variant is disease-causing. ClinVar has also classified this variant as Pathogenic (Variation ID: 1048623). The variant has been previously reported by Rasheed A, et al., 2020 for developmental delay and intellectual disabilities. Based on the above evidence this variant has been classified as Pathogenic according to the ACMG guidelines. -
Pathogenic, no assertion criteria provided	literature only	OMIM	Apr 01, 2021	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Neuberg Centre For Genomic Medicine, NCGM	-	The stop-gained variant c.787C>T (p.Arg263Ter) in the TTC5 gene has been reported in the homozygous state in an individual affected with delayed developmental milestones and intellectual disability (Rasheed et al., 2021). This variant is reported with the allele frequency (0.0007%) in the gnomAD Exomes and absent in 1000 Genomes. It has been submitted to ClinVar as Pathogenic. However, study on multiple affected individuals and functional studies on the pathogenicity of the variant is unavailable. This variant is predicted to cause a loss of normal protein function through protein truncation. Loss of function variants has been previously reported to be disease causing. For these reasons, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.60	D
BayesDel_noAF	Pathogenic	0.62
CADD	Pathogenic	41
DANN	Uncertain	1.0
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Uncertain	0.92	D
Vest4		0.35
ClinPred		1.0	D
GERP RS		4.9

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

LitVar

Other links and lift over

dbSNP: rs199831317; hg19: chr14-20763923; COSMIC: COSV51872277; COSMIC: COSV51872277;