16-2071510-G-A

Position:

• chr16-2071510-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM1 PM2 PM5 PP3

The NM_000548.5(TSC2):​c.1840G>A​(p.Ala614Thr) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 2/3 splice prediction tools predicting alterations to normal splicing. 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. A614S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TSC2 NM_000548.5 missense, splice_region
• Scores: Splicing: ADA: 0.9987
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.78

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 7 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 6 benign, 14 uncertain 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 chr16-2071511-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 49721.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TSC2	NM_000548.5	c.1840G>A	p.Ala614Thr	missense_variant, splice_region_variant	18/42	ENST00000219476.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TSC2	ENST00000219476.9	c.1840G>A	p.Ala614Thr	missense_variant, splice_region_variant	18/42	5	NM_000548.5

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

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 28, 2019

The p.A614T variant (also known as c.1840G>A) is located in coding exon 17 of the TSC2 gene. The alanine at codon 614 is replaced by threonine, an amino acid with similar properties. This change occurs in the first base pair of coding exon 17. This nucleotide position is highly conserved in available vertebrate species. This amino acid position is not well conserved in available vertebrate species. Using the BDGP and ESEfinder splice site prediction tools, this alteration is predicted to weaken the efficiency of the native splice acceptor site; however, direct evidence is unavailable. 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	0.14
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.070
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.64	D;.;.;.;.;.;.;.;.;.;.;.;D;.;D
Eigen	Uncertain	0.44
Eigen_PC	Uncertain	0.54
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.93	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.34	D
MetaRNN	Uncertain	0.68	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.076	D
MutationAssessor	Benign	1.4	L;.;.;.;L;L;.;.;.;L;.;L;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D
PrimateAI	Uncertain	0.61	T
PROVEAN	Benign	-1.0	N;.;.;N;.;N;.;.;N;N;.;.;.;.;N
REVEL	Uncertain	0.57
Sift	Benign	0.064	T;.;.;T;.;T;.;.;T;T;.;.;.;.;T
Sift4G	Uncertain	0.041	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Polyphen		0.47	P;.;.;.;P;P;.;.;P;P;.;.;.;.;.
Vest4		0.59
MutPred		0.59		Loss of helix (P = 0.0237);Loss of helix (P = 0.0237);Loss of helix (P = 0.0237);.;Loss of helix (P = 0.0237);Loss of helix (P = 0.0237);Loss of helix (P = 0.0237);Loss of helix (P = 0.0237);.;Loss of helix (P = 0.0237);Loss of helix (P = 0.0237);Loss of helix (P = 0.0237);Loss of helix (P = 0.0237);Loss of helix (P = 0.0237);.;
MVP		0.76
ClinPred		0.91	D
GERP RS		5.5
Varity_R		0.20
gMVP		0.52

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.79
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: rs397515199; hg19: chr16-2121511;