16-2076075-C-G

Position:

• chr16-2076075-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_000548.5(TSC2):​c.2647C>G​(p.Gln883Glu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,654 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. Q883Q) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.84

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 5 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 5 benign, 13 uncertain in NM_000548.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.777

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TSC2	NM_000548.5	c.2647C>G	p.Gln883Glu	missense_variant	24/42	ENST00000219476.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TSC2	ENST00000219476.9	c.2647C>G	p.Gln883Glu	missense_variant	24/42	5	NM_000548.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461654 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727122

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.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Tuberous sclerosis 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Mar 12, 2020

In summary, this is a novel missense change that is not predicted to affect protein function or cause disease. However, the evidence is insufficient at this time to prove that conclusively. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a TSC2-related disease. This sequence change replaces glutamine with glutamic acid at codon 883 of the TSC2 protein (p.Gln883Glu). The glutamine residue is highly conserved and there is a small physicochemical difference between glutamine and glutamic acid. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.16
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.25
CADD	Pathogenic	26
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.62	D;.;.;.;.;.;.;.;.;.;.;.;D;.;D
Eigen	Uncertain	0.67
Eigen_PC	Pathogenic	0.67
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.93	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Uncertain	0.23	D
MetaRNN	Pathogenic	0.78	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.47	D
MutationAssessor	Uncertain	2.3	M;.;.;.;M;M;.;.;.;M;.;M;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.85	D
PROVEAN	Benign	-1.2	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Pathogenic	0.76
Sift	Uncertain	0.026	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Sift4G	Benign	0.085	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Polyphen		0.93	P;.;.;.;P;D;.;.;P;P;.;.;.;.;.
Vest4		0.87
MutPred		0.56		Gain of ubiquitination at K880 (P = 0.0737);Gain of ubiquitination at K880 (P = 0.0737);Gain of ubiquitination at K880 (P = 0.0737);.;Gain of ubiquitination at K880 (P = 0.0737);Gain of ubiquitination at K880 (P = 0.0737);Gain of ubiquitination at K880 (P = 0.0737);Gain of ubiquitination at K880 (P = 0.0737);.;Gain of ubiquitination at K880 (P = 0.0737);Gain of ubiquitination at K880 (P = 0.0737);Gain of ubiquitination at K880 (P = 0.0737);Gain of ubiquitination at K880 (P = 0.0737);Gain of ubiquitination at K880 (P = 0.0737);.;
MVP		0.95
ClinPred		0.89	D
GERP RS		5.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.40
gMVP		0.60

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: rs45476100; hg19: chr16-2126076; COSMIC: COSV54766714; COSMIC: COSV54766714;