16-2496358-C-A

Position:

• chr16-2496358-C-A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PM2

The NM_001199107.2(TBC1D24):​c.210C>A​(p.Asp70Glu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,118 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: TBC1D24 NM_001199107.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -0.941

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]

ENSG00000260272 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a domain Rab-GAP TBC (size 215) in uniprot entity TBC24_HUMAN there are 17 pathogenic changes around while only 3 benign (85%) in NM_001199107.2
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TBC1D24	NM_001199107.2	c.210C>A	p.Asp70Glu	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.210C>A	p.Asp70Glu	missense_variant	2/8		NM_001199107.2	ENSP00000494678.1
ENSG00000260272	ENST00000564543.1	c.210C>A	p.Asp70Glu	missense_variant	1/3	2		ENSP00000455547.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461118 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726906

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

May 26, 2023

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

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

Nov 22, 2023

This sequence change replaces aspartic acid, which is acidic and polar, with glutamic acid, which is acidic and polar, at codon 70 of the TBC1D24 protein (p.Asp70Glu). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TBC1D24-related conditions. ClinVar contains an entry for this variant (Variation ID: 2503271). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on TBC1D24 protein function. 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	0.89
BayesDel_addAF	Benign	-0.027	T
BayesDel_noAF	Benign	-0.28
CADD	Benign	0.13
DANN	Uncertain	0.98
DEOGEN2	Benign	0.017	.;T;T;.;.;.;.
Eigen	Benign	-0.84
Eigen_PC	Benign	-1.1
FATHMM_MKL	Benign	0.39	N
LIST_S2	Uncertain	0.97	.;.;D;D;D;D;D
M_CAP	Uncertain	0.15	D
MetaRNN	Uncertain	0.65	D;D;D;D;D;D;D
MetaSVM	Benign	-0.72	T
MutationAssessor	Uncertain	2.4	M;M;M;.;.;M;.
PrimateAI	Uncertain	0.72	T
PROVEAN	Benign	-1.7	N;.;N;.;.;.;N
REVEL	Uncertain	0.36
Sift	Uncertain	0.014	D;.;T;.;.;.;T
Sift4G	Pathogenic	0.0	D;.;D;.;.;D;D
Polyphen		1.0	D;D;D;.;.;D;.
Vest4		0.84
MutPred		0.73		Gain of helix (P = 0.0696);Gain of helix (P = 0.0696);Gain of helix (P = 0.0696);Gain of helix (P = 0.0696);Gain of helix (P = 0.0696);Gain of helix (P = 0.0696);Gain of helix (P = 0.0696);
MVP		0.42
MPC		1.1, 1.3
ClinPred		0.80	D
GERP RS		-8.5
Varity_R		0.093
gMVP		0.59

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: rs373872223; hg19: chr16-2546359; COSMIC: COSV99036638; COSMIC: COSV99036638;