chr16-2082461-G-C

Position:

• chr16-2082461-G-C

Variant summary

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

The NM_000548.5(TSC2):​c.3840G>C​(p.Gln1280His) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 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. Q1280L) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 34)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 3.81

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.3840G>C	p.Gln1280His	missense_variant	32/42	ENST00000219476.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TSC2	ENST00000219476.9	c.3840G>C	p.Gln1280His	missense_variant	32/42	5	NM_000548.5

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 34

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

Nov 24, 2020

In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). 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 histidine at codon 1280 of the TSC2 protein (p.Gln1280His). The glutamine residue is moderately conserved and there is a small physicochemical difference between glutamine and histidine. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 18, 2024

The p.Q1280H variant (also known as c.3840G>C), located in coding exon 31 of the TSC2 gene, results from a G to C substitution at nucleotide position 3840. The glutamine at codon 1280 is replaced by histidine, 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 variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Pathogenic	0.19	D
BayesDel_noAF	Uncertain	0.030
CADD	Pathogenic	26
DANN	Uncertain	0.98
DEOGEN2	Uncertain	0.42	T;.;.;.;.
Eigen	Benign	0.080
Eigen_PC	Benign	0.19
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.86	D;D;D;D;D
M_CAP	Uncertain	0.10	D
MetaRNN	Benign	0.30	T;T;T;T;T
MetaSVM	Uncertain	0.18	D
MutationAssessor	Benign	1.4	L;.;.;.;.
MutationTaster	Benign	0.96	D;D;D;D;D;D;D
PrimateAI	Benign	0.36	T
PROVEAN	Benign	-0.74	N;.;.;.;.
REVEL	Uncertain	0.49
Sift	Uncertain	0.0080	D;.;.;.;.
Sift4G	Benign	0.20	T;.;.;.;.
Polyphen		0.88	P;B;.;.;.
Vest4		0.54
MutPred		0.24		Gain of catalytic residue at Q1280 (P = 0.0091);.;Gain of catalytic residue at Q1280 (P = 0.0091);.;.;
MVP		0.90
ClinPred		0.67	D
GERP RS		4.3
Varity_R		0.16
gMVP		0.46

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.24		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.24		Position offset: 6

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1060500941; hg19: chr16-2132462;