13-75299455-T-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_014832.5(TBC1D4):c.3031A>T(p.Ile1011Phe) variant causes a missense change. The variant allele was found at a frequency of 0.000013 in 1,461,878 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000013 (0 hom.)
• Consequence: TBC1D4 NM_014832.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.88

Genes affected

TBC1D4 (HGNC:19165): (TBC1 domain family member 4) This gene is a member of the Tre-2/BUB2/CDC16 domain family. The protein encoded by this gene is a Rab-GTPase-activating protein, and contains two phopshotyrosine-binding domains (PTB1 and PTB2), a calmodulin-binding domain (CBD), a Rab-GTPase domain, and multiple AKT phosphomotifs. This protein is thought to play an important role in glucose homeostasis by regulating the insulin-dependent trafficking of the glucose transporter 4 (GLUT4), important for removing glucose from the bloodstream into skeletal muscle and fat tissues. Reduced expression of this gene results in an increase in GLUT4 levels at the plasma membrane, suggesting that this protein is important in intracellular retention of GLUT4 under basal conditions. When exposed to insulin, this protein is phosphorylated, dissociates from GLUT4 vesicles, resulting in increased GLUT4 at the cell surface, and enhanced glucose transport. Phosphorylation of this protein by AKT is required for proper translocation of GLUT4 to the cell surface. Individuals homozygous for a mutation in this gene are at higher risk for type 2 diabetes and have higher levels of circulating glucose and insulin levels after glucose ingestion. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Aug 2015]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TBC1D4	NM_014832.5	c.3031A>T	p.Ile1011Phe	missense_variant	17/21	ENST00000377636.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TBC1D4	ENST00000377636.8	c.3031A>T	p.Ile1011Phe	missense_variant	17/21	2	NM_014832.5	A1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.0000130 AC: 19 AN: 1461878 Hom.: 0 Cov.: 32 AF XY: 0.0000165 AC XY: 12 AN XY: 727240

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000479

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

Alfa AF: 0.0000312 Hom.: 0

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 29, 2023

The c.3031A>T (p.I1011F) alteration is located in exon 17 (coding exon 17) of the TBC1D4 gene. This alteration results from a A to T substitution at nucleotide position 3031, causing the isoleucine (I) at amino acid position 1011 to be replaced by a phenylalanine (F). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.77
BayesDel_addAF	Pathogenic	0.18	D
BayesDel_noAF	Uncertain	0.020
Cadd	Pathogenic	27
Dann	Uncertain	0.99
Eigen	Uncertain	0.47
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.96	D;D;D;D
M_CAP	Benign	0.028	D
MetaRNN	Uncertain	0.54	D;D;D;D
MetaSVM	Benign	-1.0	T
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.90	D
Polyphen		0.99, 1.0, 1.0	.;D;D;D
Vest4		0.91, 0.90, 0.88
MutPred		0.61		.;.;.;Gain of catalytic residue at S1012 (P = 0);
MVP		0.84
MPC		1.4
ClinPred		0.95	D
GERP RS		5.6
Varity_R		0.60
gMVP		0.73

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: rs1876291637; hg19: chr13-75873591;