16-2496267-G-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_001199107.2(TBC1D24):c.119G>T(p.Arg40Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000186 in 1,613,656 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R40C) has been classified as Pathogenic.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TBC1D24 NM_001199107.2 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3 O: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 Pathogenic. Variant got 18 ACMG points.

• PM1: In a binding_site (size 0) in uniprot entity TBC24_HUMAN there are 5 pathogenic changes around while only 0 benign (100%) in NM_001199107.2
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr16-2496266-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 91396.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.98
• PP5: Variant 16-2496267-G-T is Pathogenic according to our data. Variant chr16-2496267-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 183152.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TBC1D24	NM_001199107.2	c.119G>T	p.Arg40Leu	missense_variant	2/8	ENST00000646147.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TBC1D24	ENST00000646147.1	c.119G>T	p.Arg40Leu	missense_variant	2/8		NM_001199107.2	A1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152258 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000402 AC: 1 AN: 249018 Hom.: 0 AF XY: 0.00 AC XY: 0 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: 0.00000886

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461398 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727016

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152258 Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2 AN XY: 74380

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000151

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

DOORS syndrome Pathogenic:2 Other:1

Pathogenic, criteria provided, single submitter	research	Lupski Lab, Baylor-Hopkins CMG, Baylor College of Medicine	Jan 01, 2014	We identified 26 families with DOORS syndrome; each patient had at least 3 of the 5 well-described features of DOORS syndrome, which include deafness, onychodystrophy, osteodystrophy, intellectual disability, and seizures. A combination of whole-exome sequencing and Sanger sequencing identified homozygous or compound heterozygous pathogenic variants in TBC1D24 in 11 individuals from 9 families. -
Pathogenic, no assertion criteria provided	literature only	Division of Medical Genetics; Sainte-Justine Hospital	Dec 22, 2014	- -
not provided, no classification provided	literature only	GeneReviews	-	- -

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

Likely pathogenic, criteria provided, single submitter

clinical testing

Invitae

Mar 20, 2023

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Arg40 amino acid residue in TBC1D24. Other variant(s) that disrupt this residue have been observed in individuals with TBC1D24-related conditions (PMID: 24291220; Invitae), which suggests that this may be a clinically significant amino acid residue. Experimental studies are conflicting or provide insufficient evidence to determine the effect of this variant on TBC1D24 function (PMID: 27281533, 30335140). 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. ClinVar contains an entry for this variant (Variation ID: 183152). This missense change has been observed in individual(s) with autosomal recessive DOORS syndrome (PMID: 24291220). This variant is present in population databases (no rsID available, gnomAD 0.0009%). This sequence change replaces arginine, which is basic and polar, with leucine, which is neutral and non-polar, at codon 40 of the TBC1D24 protein (p.Arg40Leu). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.29
Cadd	Pathogenic	29
Dann	Uncertain	1.0
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Pathogenic	0.62	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D;D;D
MetaSVM	Uncertain	-0.19	T
MutationAssessor	Uncertain	2.5	M;M;M;.;.;M;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.64	T
PROVEAN	Pathogenic	-6.2	D;.;D;D;.;.;D
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		0.97
MutPred		0.87		Loss of MoRF binding (P = 0.0103);Loss of MoRF binding (P = 0.0103);Loss of MoRF binding (P = 0.0103);Loss of MoRF binding (P = 0.0103);Loss of MoRF binding (P = 0.0103);Loss of MoRF binding (P = 0.0103);Loss of MoRF binding (P = 0.0103);
MVP		0.89
MPC		1.2, 1.6
ClinPred		0.99	D
GERP RS		5.6
Varity_R		0.83
gMVP		0.90

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;