16-2071827-T-G

Variant names:

• chr16-2071827-T-G
• rs1555506028
• NM_000548.5:c.1990T>G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PM2

The NM_000548.5(TSC2):​c.1990T>G​(p.Ser664Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. S664S) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.43

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 4 ACMG points.

• PM1: In a modified_residue Phosphoserine (size 0) in uniprot entity TSC2_HUMAN
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC2	NM_000548.5	c.1990T>G	p.Ser664Ala	missense_variant	Exon 19 of 42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.1990T>G	p.Ser664Ala	missense_variant	Exon 19 of 42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Tuberous sclerosis 2 Uncertain:2

Nov 03, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces serine, which is neutral and polar, with alanine, which is neutral and non-polar, at codon 664 of the TSC2 protein (p.Ser664Ala). 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: 486707). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt TSC2 protein function with a negative predictive value of 95%. Experimental studies have shown that this missense change affects TSC2 function (PMID: 15851026). 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. -

Nov 07, 2021

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hereditary cancer-predisposing syndrome Uncertain:1

Oct 09, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.S664A variant (also known as c.1990T>G), located in coding exon 18 of the TSC2 gene, results from a T to G substitution at nucleotide position 1990. The serine at codon 664 is replaced by alanine, an amino acid with similar properties. The amino acid position S664 has been shown to mediate Erk-dependent phosphorylation of TSC2 in vitro (Ma L et al. Cell, 2005 Apr;121:179-93). This amino acid position is highly 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.21
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Uncertain	0.090
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.57	D;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Uncertain	0.36
Eigen_PC	Uncertain	0.26
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.88	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Uncertain	0.13	D
MetaRNN	Uncertain	0.69	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.42	D
MutationAssessor	Uncertain	2.4	M;.;.;.;M;M;.;.;.;M;.;M;.;.;.
PrimateAI	Uncertain	0.64	T
PROVEAN	Benign	-1.6	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Uncertain	0.60
Sift	Benign	0.10	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Sift4G	Pathogenic	0.0	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Polyphen		0.97	D;.;.;.;D;D;.;.;D;D;.;.;.;.;.
Vest4		0.49
MutPred		0.35		Loss of phosphorylation at S664 (P = 0.0069);Loss of phosphorylation at S664 (P = 0.0069);Loss of phosphorylation at S664 (P = 0.0069);.;Loss of phosphorylation at S664 (P = 0.0069);Loss of phosphorylation at S664 (P = 0.0069);Loss of phosphorylation at S664 (P = 0.0069);Loss of phosphorylation at S664 (P = 0.0069);.;Loss of phosphorylation at S664 (P = 0.0069);Loss of phosphorylation at S664 (P = 0.0069);Loss of phosphorylation at S664 (P = 0.0069);Loss of phosphorylation at S664 (P = 0.0069);Loss of phosphorylation at S664 (P = 0.0069);.;
MVP		0.88
ClinPred		0.83	D
GERP RS		5.5
Varity_R		0.15
gMVP		0.47

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: rs1555506028; hg19: chr16-2121828;