16-2496267-G-C

Position:

• chr16-2496267-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM5 PP3_Strong

The NM_001199107.2(TBC1D24):​c.119G>C​(p.Arg40Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000411 in 1,461,396 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R40H) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: TBC1D24 NM_001199107.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.59

Genes affected

TBC1D24 (HGNC:29203): (TBC1 domain family member 24) This gene encodes a protein with a conserved domain, referred to as the TBC domain, characteristic of proteins which interact with GTPases. TBC domain proteins may serve as GTPase-activating proteins for a particular group of GTPases, the Rab (Ras-related proteins in brain) small GTPases which are involved in the regulation of membrane trafficking. Mutations in this gene are associated with familial infantile myoclonic epilepsy. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Feb 2011]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM5: Other missense variant is known to change same aminoacid residue: Variant chr16-2496267-G-A is described in Lovd as [Likely_pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.973

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TBC1D24	NM_001199107.2	c.119G>C	p.Arg40Pro	missense_variant	2/8	ENST00000646147.1	NP_001186036.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TBC1D24	ENST00000646147.1	c.119G>C	p.Arg40Pro	missense_variant	2/8		NM_001199107.2	ENSP00000494678	A1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000201 AC: 5 AN: 249018 Hom.: 0 AF XY: 0.0000222 AC XY: 3 AN XY: 135266

Gnomad AFR exome AF: 0.00

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: 0.0000443

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000411 AC: 6 AN: 1461396 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 727014

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000450

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

ExAC AF: 0.0000330 AC: 4

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Developmental and epileptic encephalopathy, 1;C3892048:Autosomal dominant nonsyndromic hearing loss 65;CN236805:Caused by mutation in the TBC1 domain family, member 24 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 16, 2023

This sequence change replaces arginine, which is basic and polar, with proline, which is neutral and non-polar, at codon 40 of the TBC1D24 protein (p.Arg40Pro). This variant is present in population databases (rs760474458, gnomAD 0.004%). This variant has not been reported in the literature in individuals affected with TBC1D24-related conditions. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt TBC1D24 protein function. This variant disrupts the p.Arg40 amino acid residue in TBC1D24. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 24291220; Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.33
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Benign	0.33	.;T;T;.;.;.;.
Eigen	Pathogenic	0.87
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	.;.;D;D;D;D;D
M_CAP	Pathogenic	0.67	D
MetaRNN	Pathogenic	0.97	D;D;D;D;D;D;D
MetaSVM	Uncertain	-0.15	T
MutationAssessor	Uncertain	2.5	M;M;M;.;.;M;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.65	T
PROVEAN	Pathogenic	-6.2	D;.;D;D;.;.;D
REVEL	Pathogenic	0.87
Sift	Pathogenic	0.0	D;.;D;D;.;.;D
Sift4G	Pathogenic	0.0	D;.;D;D;.;D;D
Polyphen		1.0	D;D;D;.;.;D;.
Vest4		0.95
MutPred		0.83		Loss of MoRF binding (P = 0.0034);Loss of MoRF binding (P = 0.0034);Loss of MoRF binding (P = 0.0034);Loss of MoRF binding (P = 0.0034);Loss of MoRF binding (P = 0.0034);Loss of MoRF binding (P = 0.0034);Loss of MoRF binding (P = 0.0034);
MVP		0.94
MPC		1.3, 1.7
ClinPred		0.96	D
GERP RS		5.6
Varity_R		0.96
gMVP		0.95

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: rs760474458; hg19: chr16-2546268;