chr17-82924958-C-A

Position:

• chr17-82924958-C-A

Variant summary

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

The NM_005993.5(TBCD):​c.2280C>A​(p.Tyr760Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000706 in 1,416,022 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 Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 7.1e-7 (0 hom.)
• Consequence: TBCD NM_005993.5 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: -1.01

Genes affected

TBCD (HGNC:11581): (tubulin folding cofactor D) Cofactor D is one of four proteins (cofactors A, D, E, and C) involved in the pathway leading to correctly folded beta-tubulin from folding intermediates. Cofactors A and D are believed to play a role in capturing and stabilizing beta-tubulin intermediates in a quasi-native confirmation. Cofactor E binds to the cofactor D/beta-tubulin complex; interaction with cofactor C then causes the release of beta-tubulin polypeptides that are committed to the native state. [provided by RefSeq, Jul 2008]

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 17-82924958-C-A is Pathogenic according to our data. Variant chr17-82924958-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 268170.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TBCD	NM_005993.5	c.2280C>A	p.Tyr760Ter	stop_gained	27/39	ENST00000355528.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TBCD	ENST00000355528.9	c.2280C>A	p.Tyr760Ter	stop_gained	27/39	1	NM_005993.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 7.06e-7 AC: 1 AN: 1416022 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 700146

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000268

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.: 33

ExAC AF: 0.00000842 AC: 1

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jun 20, 2023	For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 268170). This premature translational stop signal has been observed in individual(s) with early-onset neurodegenerative encephalopathy (PMID: 27666374). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Tyr760*) in the TBCD gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in TBCD are known to be pathogenic (PMID: 27666370, 27666374). -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Jul 18, 2017	The Y760X variant in the TBCD gene has been reported previously in the compound heterozygous state with a second TBCD variant in association with early-onset neurodegenerative encephalopathy (Miyake et al., 2016). This variant is predicted to cause loss of normal protein function either through protein truncation or nonsense-mediated mRNA decay. The Y760X variant is not observed in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). We interpret Y760X as a pathogenic variant. -

Early-onset progressive diffuse brain atrophy-microcephaly-muscle weakness-optic atrophy syndrome Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Nov 16, 2016

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	0.070
CADD	Pathogenic	26
DANN	Benign	0.97
Eigen	Benign	-0.36
Eigen_PC	Benign	-0.80
FATHMM_MKL	Benign	0.16	N
MutationTaster	Benign	1.0	A;A
Vest4		0.95
GERP RS		-5.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8

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: rs754750539; hg19: chr17-80882834;