16-2053371-C-T

Position:

• chr16-2053371-C-T

Variant summary

Our verdict is Benign. Variant got -17 ACMG points: 0P and 17B. BP4_Strong BP6_Very_Strong BP7 BS2

The NM_000548.5(TSC2):​c.255C>T​(p.Val85=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00124 in 1,590,176 control chromosomes in the GnomAD database, including 4 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.00081 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0013 (4 hom.)
• Consequence: TSC2 NM_000548.5 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:20 O:1
• Conservation: PhyloP100: -1.30

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 Benign. Variant got -17 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.75).
• BP6: Variant 16-2053371-C-T is Benign according to our data. Variant chr16-2053371-C-T is described in ClinVar as [Likely_benign]. Clinvar id is 49572.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-2053371-C-T is described in Lovd as [Likely_benign]. Variant chr16-2053371-C-T is described in Lovd as [Benign].
• BP7: Synonymous conserved (PhyloP=-1.3 with no splicing effect.
• BS2: High AC in GnomAd4 at 123 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TSC2	NM_000548.5	c.255C>T	p.Val85=	synonymous_variant	4/42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.255C>T	p.Val85=	synonymous_variant	4/42	5	NM_000548.5	ENSP00000219476

Frequencies

GnomAD3 genomes AF: 0.000808 AC: 123 AN: 152222 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.000314

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000851

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000414

Gnomad FIN AF: 0.000941

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00123

Gnomad OTH AF: 0.000478

GnomAD3 exomes AF: 0.00118 AC: 248 AN: 209850 Hom.: 0 AF XY: 0.00110 AC XY: 125 AN XY: 113228

Gnomad AFR exome AF: 0.000634

Gnomad AMR exome AF: 0.000980

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.000459

Gnomad FIN exome AF: 0.00159

Gnomad NFE exome AF: 0.00177

Gnomad OTH exome AF: 0.00114

GnomAD4 exome AF: 0.00129 AC: 1853 AN: 1437836 Hom.: 4 Cov.: 31 AF XY: 0.00124 AC XY: 886 AN XY: 713026

Gnomad4 AFR exome AF: 0.000363

Gnomad4 AMR exome AF: 0.000988

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.000353

Gnomad4 FIN exome AF: 0.00112

Gnomad4 NFE exome AF: 0.00146

Gnomad4 OTH exome AF: 0.00168

GnomAD4 genome AF: 0.000807 AC: 123 AN: 152340 Hom.: 0 Cov.: 33 AF XY: 0.000765 AC XY: 57 AN XY: 74490

Gnomad4 AFR AF: 0.000313

Gnomad4 AMR AF: 0.000849

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000414

Gnomad4 FIN AF: 0.000941

Gnomad4 NFE AF: 0.00123

Gnomad4 OTH AF: 0.000473

Alfa AF: 0.00137 Hom.: 0

Bravo AF: 0.000865

Asia WGS AF: 0.000577 AC: 2 AN: 3478

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:20 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:7

Likely benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Feb 21, 2013	Val85Val in exon 4 of TSC2: This variant is not expected to have clinical significance because it does not alter an amino acid residue and is not located within the splice consensus sequence. It has been identified in 0.2% (16/8582) of European American chromosomes from a broad population by the NHLBI Exome Sequencing Project (http://evs.gs.washington.edu/EVS; dbSNP rs45517098). -
Benign, criteria provided, single submitter	clinical testing	PreventionGenetics, part of Exact Sciences	-	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Apr 01, 2013	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Benign, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Feb 12, 2016	- -
Benign, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Aug 14, 2021	- -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Oct 08, 2018	Variant summary: TSC2 c.255C>T alters a non-conserved nucleotide resulting in a synonymous change. 5/5 computational tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.0011 in 235020 control chromosomes (gnomAD). The observed variant frequency is approximately 16-folds higher than the estimated maximal expected allele frequency for a pathogenic variant in TSC2 causing Tuberous Sclerosis Complex phenotype (6.9e-05), strongly suggesting that the variant is benign. To our knowledge, no occurrence of c.255C>T in individuals affected with Tuberous Sclerosis Complex and no experimental evidence demonstrating its impact on protein function have been reported. Four ClinVar submissions from clinical diagnostic laboratories (evaluation after 2014) cites the variant as likely benign/benign. Based on the evidence outlined above, the variant was classified as benign. -

Tuberous sclerosis 2 Benign:5

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Benign, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Feb 01, 2024	- -
Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	May 30, 2017	- -
Benign, criteria provided, single submitter	clinical testing	KCCC/NGS Laboratory, Kuwait Cancer Control Center	Jul 07, 2023	- -
Benign, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Sep 16, 2022	- -

not provided Benign:4

Likely benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Aug 01, 2024	TSC2: BP4, BP7 -
Likely benign, no assertion criteria provided	clinical testing	Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)	-	- -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Likely benign, criteria provided, single submitter	not provided	Breakthrough Genomics, Breakthrough Genomics	-	- -

Tuberous sclerosis syndrome Benign:2 Other:1

not provided, no classification provided	curation	Tuberous sclerosis database (TSC2)	-	- -
Benign, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Feb 05, 2024	- -
Benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 13, 2018	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Hereditary cancer-predisposing syndrome Benign:2

Likely benign, criteria provided, single submitter	clinical testing	Ambry Genetics	Oct 07, 2014	This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -
Benign, criteria provided, single submitter	curation	Sema4, Sema4	Oct 30, 2020	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.75
CADD	Benign	0.29
DANN	Benign	0.55
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs45517098; hg19: chr16-2103372;