16-2087899-C-A

Variant names:

• chr16-2087899-C-A
• rs201707249
• NM_000548.5:c.5026C>A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PM5

The NM_000548.5(TSC2):​c.5026C>A​(p.Leu1676Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. L1676P) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.77

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a domain Rap-GAP (size 227) in uniprot entity TSC2_HUMAN there are 284 pathogenic changes around while only 47 benign (86%) in NM_000548.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr16-2087900-T-C is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TSC2	NM_000548.5	c.5026C>A	p.Leu1676Met	missense_variant	Exon 39 of 42	ENST00000219476.9	NP_000539.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TSC2	ENST00000219476.9	c.5026C>A	p.Leu1676Met	missense_variant	Exon 39 of 42	5	NM_000548.5	ENSP00000219476.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1

Aug 08, 2019

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.L1676M variant (also known as c.5026C>A), located in coding exon 38 of the TSC2 gene, results from a C to A substitution at nucleotide position 5026. The leucine at codon 1676 is replaced by methionine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.29
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.11
CADD	Benign	23
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.77	D;.;.;.;.;.;.;.;.;.;.;.;D;.;D
Eigen	Benign	0.17
Eigen_PC	Benign	0.12
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Uncertain	0.95	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.43	D
MetaRNN	Uncertain	0.66	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.73	D
MutationAssessor	Benign	1.5	L;.;.;.;.;.;.;.;.;.;.;.;.;.;.
PrimateAI	Uncertain	0.68	T
PROVEAN	Benign	-1.4	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Pathogenic	0.70
Sift	Uncertain	0.0040	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Sift4G	Pathogenic	0.0	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Polyphen		1.0	D;.;.;.;D;D;.;.;D;D;.;.;.;.;.
Vest4		0.54
MutPred		0.60		Gain of sheet (P = 0.1208);.;.;.;.;.;.;.;.;.;.;.;.;.;.;
MVP		0.76
ClinPred		0.87	D
GERP RS		3.6
RBP_binding_hub_radar		0.97
RBP_regulation_power_radar		2.7
Varity_R		0.64
gMVP		0.49

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs201707249; hg19: chr16-2137900;