chr16-2058858-G-T

Position:

• chr16-2058858-G-T

Variant summary

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

The NM_000548.5(TSC2):​c.960G>T​(p.Leu320Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000687 in 1,456,144 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: 6.9e-7 (0 hom.)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2 O:1
• Conservation: PhyloP100: 1.33

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]

TSC2 (HGNC:):

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	Protein	UniProt
TSC2	NM_000548.5	c.960G>T	p.Leu320Phe	missense_variant	10/42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.960G>T	p.Leu320Phe	missense_variant	10/42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.87e-7 AC: 1 AN: 1456144 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 723642

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: 9.01e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 19, 2023

This sequence change replaces leucine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 320 of the TSC2 protein (p.Leu320Phe). This variant is not present in population databases (gnomAD no frequency). 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. 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 not expected to disrupt TSC2 protein function. ClinVar contains an entry for this variant (Variation ID: 49408). This variant has not been reported in the literature in individuals affected with TSC2-related conditions. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 03, 2017

The p.L320F variant (also known as c.960G>T), located in coding exon 9 of the TSC2 gene, results from a G to T substitution at nucleotide position 960. The leucine at codon 320 is replaced by phenylalanine, an amino acid with highly similar properties. This alteration was detected in an individual with a clinical diagnosis of tuberous sclerosis complex (TSC); however authors referred to the alteration as p.F320L (c.978T>G) (Zhang H et al. J. Hum. Genet., 1999;44:391-6). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be probably damaging and deleterious by PolyPhen and SIFT in silico analyses, respectively. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Tuberous sclerosis syndrome Other:1

not provided, no classification provided

curation

Tuberous sclerosis database (TSC2)

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.88
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.26
CADD	Benign	19
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.84	D;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Uncertain	0.27
Eigen_PC	Benign	0.15
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.89	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.57	D
MetaRNN	Uncertain	0.58	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.12	D
MutationAssessor	Uncertain	2.6	M;.;.;.;M;M;.;.;.;M;.;M;.;.;.
PrimateAI	Uncertain	0.75	T
PROVEAN	Uncertain	-3.6	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
REVEL	Uncertain	0.47
Sift	Pathogenic	0.0	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Sift4G	Pathogenic	0.0	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Polyphen		1.0	D;.;.;.;D;D;.;.;D;D;.;.;.;.;.
Vest4		0.91
MutPred		0.17		Gain of catalytic residue at L320 (P = 0.0602);Gain of catalytic residue at L320 (P = 0.0602);Gain of catalytic residue at L320 (P = 0.0602);.;Gain of catalytic residue at L320 (P = 0.0602);Gain of catalytic residue at L320 (P = 0.0602);Gain of catalytic residue at L320 (P = 0.0602);Gain of catalytic residue at L320 (P = 0.0602);.;Gain of catalytic residue at L320 (P = 0.0602);Gain of catalytic residue at L320 (P = 0.0602);Gain of catalytic residue at L320 (P = 0.0602);Gain of catalytic residue at L320 (P = 0.0602);Gain of catalytic residue at L320 (P = 0.0602);.;
MVP		0.87
ClinPred		1.0	D
GERP RS		4.2
Varity_R		0.63
gMVP		0.70

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: rs1131825; hg19: chr16-2108859;