16-2080324-A-T

Variant names:

• chr16-2080324-A-T
• rs137854421
• NM_000548.5:c.3557A>T

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM2 BP4_Moderate BP6

The NM_000548.5(TSC2):​c.3557A>T​(p.Tyr1186Phe) 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 1,460,432 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/22 in silico tools predict a benign outcome for this variant. 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. Y1186S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:1
• Conservation: PhyloP100: 1.79
• Publications: 10 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: Likely_benign. The variant received -1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.12841856).
• BP6: Variant 16-2080324-A-T is Benign according to our data. Variant chr16-2080324-A-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 663289.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC2	NM_000548.5	c.3557A>T	p.Tyr1186Phe	missense_variant	Exon 30 of 42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.3557A>T	p.Tyr1186Phe	missense_variant	Exon 30 of 42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00000400 AC: 1 AN: 249786 AF XY: 0.00000737

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000890

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460432 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 726514

⚠️ 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: 33468

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86248

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52130

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5684

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111980

Other (OTH) AF: 0.00 AC: 0 AN: 60364

⚠️ 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.: 33

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Tuberous sclerosis syndrome Uncertain:1

Feb 22, 2024

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces tyrosine with phenylalanine at codon 1186 of the TSC2 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with TSC2-related disorders in the literature. This variant has been identified in 1/249786 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance.

not provided Uncertain:1

Feb 09, 2024

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In silico analysis supports that this missense variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge

Hereditary cancer-predisposing syndrome Uncertain:1

Apr 03, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Y1186F variant (also known as c.3557A>T), located in coding exon 29 of the TSC2 gene, results from an A to T substitution at nucleotide position 3557. The tyrosine at codon 1186 is replaced by phenylalanine, an amino acid with highly similar properties. This amino acid position is not 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 2 Benign:1

Nov 05, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.10
BayesDel_addAF	Uncertain	0.046	T
BayesDel_noAF	Benign	-0.17
CADD	Benign	19
DANN	Benign	0.44
DEOGEN2	Benign	0.42	T;.;.;.;.;.;.;.;.;.;.;.;T;.;T
Eigen	Benign	-0.69
Eigen_PC	Benign	-0.62
FATHMM_MKL	Benign	0.54	D
LIST_S2	Uncertain	0.92	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Uncertain	0.12	D
MetaRNN	Benign	0.13	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Uncertain	-0.097	T
MutationAssessor	Benign	1.2	L;.;.;.;.;.;.;.;.;L;.;.;.;.;.
PhyloP100		1.8
PrimateAI	Benign	0.47	T
PROVEAN	Benign	-0.74	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Uncertain	0.35
Sift	Benign	0.29	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Sift4G	Benign	0.84	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Vest4		0.47
ClinPred		0.044	T
GERP RS		2.4
Varity_R		0.065
gMVP		0.33
Mutation Taster		=89/11	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: rs137854421; hg19: chr16-2130325;