16-2062543-A-T

Position:

• chr16-2062543-A-T

Variant summary

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

The NM_000548.5(TSC2):​c.1304A>T​(p.His435Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,460,226 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. H435Y) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 8.95

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.1304A>T	p.His435Leu	missense_variant	13/42	ENST00000219476.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TSC2	ENST00000219476.9	c.1304A>T	p.His435Leu	missense_variant	13/42	5	NM_000548.5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1460226 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726168

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

Tuberous sclerosis 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 06, 2023

This sequence change replaces histidine, which is basic and polar, with leucine, which is neutral and non-polar, at codon 435 of the TSC2 protein (p.His435Leu). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TSC2-related conditions. ClinVar contains an entry for this variant (Variation ID: 535964). 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 with a negative predictive value of 95%. 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. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 11, 2022

The p.H435L variant (also known as c.1304A>T), located in coding exon 12 of the TSC2 gene, results from an A to T substitution at nucleotide position 1304. The histidine at codon 435 is replaced by leucine, an amino acid with similar properties. This amino acid position is conserved. 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	0.24
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
CADD	Benign	22
DANN	Benign	0.96
DEOGEN2	Uncertain	0.79	D;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Benign	0.017
Eigen_PC	Benign	0.13
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.81	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
M_CAP	Uncertain	0.20	D
MetaRNN	Uncertain	0.65	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Benign	-0.36	T
MutationAssessor	Uncertain	2.2	M;.;.;.;M;M;.;.;.;M;.;M;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D
PrimateAI	Uncertain	0.60	T
PROVEAN	Uncertain	-4.2	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
REVEL	Uncertain	0.62
Sift	Benign	0.48	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Sift4G	Benign	0.13	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Polyphen		0.23	B;.;.;.;B;B;.;.;B;B;.;.;.;.;.
Vest4		0.80
MutPred		0.39		Loss of methylation at K438 (P = 0.0955);Loss of methylation at K438 (P = 0.0955);Loss of methylation at K438 (P = 0.0955);.;Loss of methylation at K438 (P = 0.0955);Loss of methylation at K438 (P = 0.0955);Loss of methylation at K438 (P = 0.0955);Loss of methylation at K438 (P = 0.0955);.;Loss of methylation at K438 (P = 0.0955);Loss of methylation at K438 (P = 0.0955);Loss of methylation at K438 (P = 0.0955);Loss of methylation at K438 (P = 0.0955);Loss of methylation at K438 (P = 0.0955);.;
MVP		0.98
ClinPred		0.95	D
GERP RS		5.2
Varity_R		0.36
gMVP		0.65

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: rs1555501389; hg19: chr16-2112544;