NM_000548.5:c.149T>G

Variant names:

• chr16-2050410-T-G
• rs1060500955
• NM_000548.5:c.149T>G

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_000548.5(TSC2):​c.149T>G​(p.Met50Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,640 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/22 in silico tools predict 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. M50V) has been classified as Benign.

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.74
• Publications: 0 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.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 8 benign, 31 uncertain in NM_000548.5
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.10912722).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC2	NM_000548.5	c.149T>G	p.Met50Arg	missense_variant	Exon 3 of 42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.149T>G	p.Met50Arg	missense_variant	Exon 3 of 42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461640 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727126

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33474

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53322

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111902

Other (OTH) AF: 0.00 AC: 0 AN: 60374

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 30

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1

Sep 09, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.M50R variant (also known as c.149T>G), located in coding exon 2 of the TSC2 gene, results from a T to G substitution at nucleotide position 149. The methionine at codon 50 is replaced by arginine, an amino acid with similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be tolerated by in silico analysis. 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	0.081
BayesDel_addAF	Uncertain	0.017	T
BayesDel_noAF	Benign	-0.21
CADD	Benign	21
DANN	Benign	0.94
DEOGEN2	Benign	0.38	T;.;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Benign	-0.75
Eigen_PC	Benign	-0.66
FATHMM_MKL	Benign	0.29	N
LIST_S2	Uncertain	0.88	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Uncertain	0.15	D
MetaRNN	Benign	0.043	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.64	T
MutationAssessor	Benign	0.0	N;.;.;.;N;N;.;.;N;N;.;.;N;.;.;.
PhyloP100		2.7
PrimateAI	Benign	0.36	T
PROVEAN	Benign	-0.71	N;.;.;N;.;N;.;.;N;N;.;.;.;.;.;N
REVEL	Benign	0.14
Sift	Benign	0.40	T;.;.;D;.;T;.;.;T;T;.;.;.;.;.;T
Sift4G	Benign	0.71	T;.;.;D;.;T;.;.;T;T;.;.;.;.;.;T
Polyphen		0.046	B;.;.;.;.;B;.;.;B;B;.;.;.;.;.;.
Vest4		0.32
MutPred		0.51		Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);.;Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);Gain of solvent accessibility (P = 0.0055);.;
MVP		0.28
ClinPred		0.054	T
GERP RS		3.6
Varity_R		0.13
gMVP		0.21
Mutation Taster		=14/186	disease causing

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: rs1060500955; hg19: chr16-2100411;