chr16-2088457-A-C

Position:

• chr16-2088457-A-C

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_000548.5(TSC2):​c.5271A>C​(p.Glu1757Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,544 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 Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -0.147

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.

• PM1: In a domain Rap-GAP (size 227) in uniprot entity TSC2_HUMAN there are 284 pathogenic changes around while only 47 benign (86%) in NM_000548.5
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.17520618).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TSC2	NM_000548.5	c.5271A>C	p.Glu1757Asp	missense_variant	42/42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.5271A>C	p.Glu1757Asp	missense_variant	42/42	5	NM_000548.5	ENSP00000219476

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460544 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 726568

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: 8.99e-7

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

Aug 30, 2021

This sequence change replaces glutamic acid with aspartic acid at codon 1757 of the TSC2 protein (p.Glu1757Asp). The glutamic acid residue is moderately conserved and there is a small physicochemical difference between glutamic acid and aspartic acid. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with TSC2-related conditions. 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. 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

Feb 02, 2024

The p.E1757D variant (also known as c.5271A>C), located in coding exon 41 of the TSC2 gene, results from an A to C substitution at nucleotide position 5271. The glutamic acid at codon 1757 is replaced by aspartic acid, an amino acid with highly similar properties. This amino acid position is conserved. In addition, the in silico prediction for this alteration is inconclusive. Based on the available evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.078
BayesDel_addAF	Pathogenic	0.19	D
BayesDel_noAF	Uncertain	0.030
CADD	Benign	10
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.45	T;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Benign	-0.92
Eigen_PC	Benign	-1.1
FATHMM_MKL	Benign	0.17	N
LIST_S2	Uncertain	0.92	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Uncertain	0.096	D
MetaRNN	Benign	0.18	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Uncertain	0.27	D
MutationAssessor	Benign	1.8	L;.;.;.;.;.;.;.;.;.;.;.;.;.;.
MutationTaster	Benign	0.99	N;N;N;N;N;N;N
PrimateAI	Benign	0.41	T
PROVEAN	Benign	-1.2	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Uncertain	0.60
Sift	Benign	0.065	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Sift4G	Benign	0.16	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Polyphen		0.33	B;.;.;.;B;B;.;.;D;B;.;.;.;.;.
Vest4		0.38
MutPred		0.17		Gain of MoRF binding (P = 0.1055);.;.;.;.;.;.;.;.;.;.;.;.;.;.;
MVP		0.91
ClinPred		0.27	T
GERP RS		-5.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.070
gMVP		0.38

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: rs1060500967; hg19: chr16-2138458;