NM_144628.4:c.1060C>T

Variant names:

• chr20-438738-G-A
• NM_144628.4:c.1060C>T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PVS1_Strong PM2

The NM_144628.4(TBC1D20):​c.1060C>T​(p.Arg354*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,894 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: TBC1D20 NM_144628.4 stop_gained
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.69

Genes affected

TBC1D20 (HGNC:16133): (TBC1 domain family member 20) This gene encodes a protein that belongs to a family of GTPase activator proteins of Rab-like small GTPases. The encoded protein and its cognate GTPase, Rab1, bind the nonstructural protein 5A (NS5A) of the hepatitis C virus (HCV) to mediate viral replication. Depletion of this protein inhibits replication of the virus and HCV infection. Mutations in this gene are associated with Warburg micro syndrome 4. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Mar 2014]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.125 CDS is truncated, and there are 0 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TBC1D20	NM_144628.4	c.1060C>T	p.Arg354*	stop_gained	Exon 8 of 8	ENST00000354200.5	NP_653229.1
TBC1D20	NR_111901.2	n.1188C>T		non_coding_transcript_exon_variant	Exon 8 of 10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TBC1D20	ENST00000354200.5	c.1060C>T	p.Arg354*	stop_gained	Exon 8 of 8	1	NM_144628.4	ENSP00000346139.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461894 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727248

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	36
DANN	Uncertain	1.0
Eigen	Uncertain	0.47
Eigen_PC	Uncertain	0.33
FATHMM_MKL	Uncertain	0.80	D
Vest4		0.18
GERP RS		5.2

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr20-419382;