chr16-2062520-C-G

Variant names:

• chr16-2062520-C-G
• rs45478892
• NM_000548.5:c.1281C>G

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_000548.5(TSC2):​c.1281C>G​(p.Ile427Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000206 in 1,459,634 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I427V) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:4 B:1 O:1
• Conservation: PhyloP100: -0.178
• Publications: 7 publications found

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 Gene-Disease associations (from GenCC):

• tuberous sclerosis

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• tuberous sclerosis 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: PanelApp Australia, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), G2P, Genomics England PanelApp, Ambry Genetics
• lymphangioleiomyomatosis

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• tuberous sclerosis complex

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• 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.1281C>G	p.Ile427Met	missense_variant	Exon 13 of 42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.1281C>G	p.Ile427Met	missense_variant	Exon 13 of 42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000206 AC: 3 AN: 1459634 Hom.: 0 Cov.: 31 AF XY: 0.00000276 AC XY: 2 AN XY: 725796

African (AFR) AF: 0.00 AC: 0 AN: 33460

American (AMR) AF: 0.0000449 AC: 2 AN: 44500

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26048

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39688

South Asian (SAS) AF: 0.00 AC: 0 AN: 85570

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53234

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5760

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111040

Other (OTH) AF: 0.00 AC: 0 AN: 60334

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:4 Benign:1 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Tuberous sclerosis 2 Uncertain:1 Benign:1

Nov 07, 2021

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Aug 05, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Lymphangiomyomatosis;C1846385:Isolated focal cortical dysplasia type II;C1860707:Tuberous sclerosis 2 Uncertain:1

May 31, 2022

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Uncertain:1

Aug 30, 2024

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The TSC2 c.1281C>G (p.Ile427Met) variant has been reported in the published literature in an individual suspected of having TSC (PMID: 22903760 (2013)).A functional study have reported inconclusive results on the effect this variant has on protein function (PMID: 22903760 (2013)). This variant has not been reported in large, multi-ethnic general populations (Genome Aggregation Database, http://gnomad.broadinstitute.org). Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded conflicting predictions that this variant is benign or damaging. Based on the available information, we are unable to determine the clinical significance of this variant. -

Hereditary cancer-predisposing syndrome Uncertain:1

Mar 04, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.I427M variant (also known as c.1281C>G), located in coding exon 12 of the TSC2 gene, results from a C to G substitution at nucleotide position 1281. The isoleucine at codon 427 is replaced by methionine, an amino acid with highly similar properties. This alteration has been reported in at least one individual with suspected tuberous sclerosis complex (Hoogeveen-Westerveld M et al. Hum Mutat, 2013 Jan;34:167-75). In one functional study, this alteration was found to have intermediate loss of the TSC1-TSC2 dependent inhibition of TORC1. (Hoogeveen-Westerveld M et al. Hum Mutat, 2013 Jan;34:167-75). This amino acid position is well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Based on the available evidence, the clinical significance of this variant remains unclear. -

Tuberous sclerosis syndrome Other:1

-

Tuberous sclerosis database (TSC2)

Significance: not provided

Review Status: no classification provided

Collection Method: curation

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.39
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.11
CADD	Benign	14
DANN	Benign	0.76
DEOGEN2	Uncertain	0.63	D;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Benign	-0.49
Eigen_PC	Benign	-0.72
FATHMM_MKL	Benign	0.23	N
LIST_S2	Uncertain	0.89	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Uncertain	0.21	D
MetaRNN	Uncertain	0.44	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Uncertain	0.22	D
MutationAssessor	Benign	1.8	L;.;.;.;L;L;.;.;.;L;.;L;.;.;.
PhyloP100		-0.18
PrimateAI	Uncertain	0.60	T
PROVEAN	Benign	-2.2	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Uncertain	0.58
Sift	Benign	0.073	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Sift4G	Uncertain	0.0020	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Polyphen		1.0	D;.;.;.;D;D;.;.;D;P;.;.;.;.;.
Vest4		0.78
MutPred		0.45		Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);.;Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);.;Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);Gain of disorder (P = 0.051);.;
MVP		0.80
ClinPred		0.17	T
GERP RS		-2.1
PromoterAI		0.0058	Neutral
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.31
gMVP		0.58
Mutation Taster		=61/39	polymorphism

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

Other links and lift over

dbSNP: rs45478892; hg19: chr16-2112521;