16-2064421-C-G

Position:

• chr16-2064421-C-G

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 2P and 3B. PM2 BP4_Moderate BP6

The NM_001406698.1(TSC2):​c.-10C>G variant causes a 5 prime UTR premature start codon gain change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,154 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: TSC2 NM_001406698.1 5_prime_UTR_premature_start_codon_gain
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:2
• Conservation: PhyloP100: -4.10

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 Likely_benign. Variant got -1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.2502142).
• BP6: Variant 16-2064421-C-G is Benign according to our data. Variant chr16-2064421-C-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 421682.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=2, Uncertain_significance=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TSC2	NM_000548.5	c.1593C>G	p.Ile531Met	missense_variant	15/42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.1593C>G	p.Ile531Met	missense_variant	15/42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461154 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 726856

Gnomad4 AFR exome AF: 0.0000299

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: 0.0000189

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2 Benign:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Tuberous sclerosis 2 Uncertain:1 Benign:1

Likely benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 16, 2024	This sequence change replaces isoleucine, which is neutral and non-polar, with methionine, which is neutral and non-polar, at codon 531 of the TSC2 protein (p.Ile531Met). 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: 421682). 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

Oct 12, 2023

The p.I531M variant (also known as c.1593C>G), located in coding exon 14 of the TSC2 gene, results from a C to G substitution at nucleotide position 1593. The isoleucine at codon 531 is replaced by methionine, an amino acid with highly similar properties. This amino acid position is well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

not provided Benign:1

Likely benign, criteria provided, single submitter

clinical testing

GeneDx

May 22, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.17
BayesDel_addAF	Uncertain	0.078	D
BayesDel_noAF	Benign	-0.13
CADD	Benign	0.27
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.59	D;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Benign	-0.78
Eigen_PC	Benign	-0.97
FATHMM_MKL	Benign	0.048	N
LIST_S2	Uncertain	0.87	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Uncertain	0.085	D
MetaRNN	Benign	0.25	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.30	T
MutationAssessor	Uncertain	2.3	M;.;.;.;M;M;.;.;.;M;.;M;.;.;.
PrimateAI	Benign	0.46	T
PROVEAN	Benign	-1.6	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Uncertain	0.49
Sift	Benign	0.24	T;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Sift4G	Uncertain	0.0090	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Polyphen		1.0	D;.;.;.;P;P;.;.;P;B;.;.;.;.;.
Vest4		0.73
MutPred		0.58		Gain of catalytic residue at M535 (P = 0.028);Gain of catalytic residue at M535 (P = 0.028);Gain of catalytic residue at M535 (P = 0.028);.;Gain of catalytic residue at M535 (P = 0.028);Gain of catalytic residue at M535 (P = 0.028);Gain of catalytic residue at M535 (P = 0.028);Gain of catalytic residue at M535 (P = 0.028);.;Gain of catalytic residue at M535 (P = 0.028);Gain of catalytic residue at M535 (P = 0.028);Gain of catalytic residue at M535 (P = 0.028);Gain of catalytic residue at M535 (P = 0.028);Gain of catalytic residue at M535 (P = 0.028);.;
MVP		0.83
ClinPred		0.34	T
GERP RS		-6.9
Varity_R		0.11
gMVP		0.38

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: rs45517180; hg19: chr16-2114422;