16-2081787-G-T

Variant summary

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

The NM_000548.5(TSC2):c.3803G>T(p.Arg1268Leu) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. 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. R1268C) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 34)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 4.67

Genes affected

TSC2 (HGNC:12363): (TSC complex subunit 2) This gene is a tumor suppressor gene that encodes the growth inhibitory protein tuberin. Tuberin interacts with hamartin to form the TSC protein complex which functions in the control of cell growth. This TSC protein complex negatively regulates mammalian target of rapamycin complex 1 (mTORC1) signaling which is a major regulator of anabolic cell growth. Mutations in this gene have been associated with tuberous sclerosis and lymphangioleiomyomatosis. [provided by RefSeq, May 2022]

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
TSC2	NM_000548.5	c.3803G>T	p.Arg1268Leu	missense_variant	31/42	ENST00000219476.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TSC2	ENST00000219476.9	c.3803G>T	p.Arg1268Leu	missense_variant	31/42	5	NM_000548.5

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 34

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 25, 2019

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. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with TSC2-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces arginine with leucine at codon 1268 of the TSC2 protein (p.Arg1268Leu). The arginine residue is moderately conserved and there is a moderate physicochemical difference between arginine and leucine. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 17, 2023

The p.R1268L variant (also known as c.3803G>T), located in coding exon 30 of the TSC2 gene, results from a G to T substitution at nucleotide position 3803. The arginine at codon 1268 is replaced by leucine, an amino acid with dissimilar properties. This amino acid position is well conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.29
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
Cadd	Pathogenic	27
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.76	D;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Benign	0.15
Eigen_PC	Benign	0.068
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Uncertain	0.95	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.46	D
MetaRNN	Uncertain	0.69	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.79	D
MutationAssessor	Uncertain	2.3	M;.;.;.;.;.;.;.;.;M;.;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D
PrimateAI	Uncertain	0.54	T
PROVEAN	Benign	-2.4	N;.;.;D;.;N;.;.;D;N;.;.;.;.;N
REVEL	Uncertain	0.61
Sift	Uncertain	0.0080	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Sift4G	Uncertain	0.040	D;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Polyphen		0.99	D;.;.;.;B;D;.;.;D;D;.;.;.;.;.
Vest4		0.79
MutPred		0.33		Loss of phosphorylation at T1271 (P = 0.0571);.;Loss of phosphorylation at T1271 (P = 0.0571);.;.;.;.;Loss of phosphorylation at T1271 (P = 0.0571);.;Loss of phosphorylation at T1271 (P = 0.0571);.;.;.;.;.;
MVP		0.96
ClinPred		0.89	D
GERP RS		4.5
Varity_R		0.18
gMVP		0.63

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs200577441; hg19: chr16-2131788;