rs377132822

Positions:

• chr9-132897550-G-A
• chr9-132897550-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 3P and 1B. PM2 PP2 BP4

The NM_000368.5(TSC1):​c.2686C>T​(p.Leu896Phe) variant causes a missense change. The variant allele was found at a frequency of 0.000000727 in 1,376,034 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts 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. L896I) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 7.3e-7 (0 hom.)
• Consequence: TSC1 NM_000368.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.63

Genes affected

TSC1 (HGNC:12362): (TSC complex subunit 1) This gene is a tumor suppressor gene that encodes the growth inhibitory protein hamartin. The encoded protein interacts with and stabilizes the GTPase activating protein tuberin. This hamartin-tuberin complex negatively regulates mammalian target of rapamycin complex 1 (mTORC1) signaling which is a major regulator of anabolic cell growth. This protein also functions as a co-chaperone for Hsp90 that inhibits its ATPase activity. This protein functions as a facilitator of Hsp90-mediated folding of kinase and non-kinase clients, including TSC2 and thereby preventing their ubiquitination and proteasomal degradation. Mutations in this gene have been associated with tuberous sclerosis and lymphangioleiomyomatosis. [provided by RefSeq, May 2022]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, TSC1
• BP4: Computational evidence support a benign effect (MetaRNN=0.26802254).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TSC1	NM_000368.5	c.2686C>T	p.Leu896Phe	missense_variant	21/23	ENST00000298552.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TSC1	ENST00000298552.9	c.2686C>T	p.Leu896Phe	missense_variant	21/23	1	NM_000368.5	P4

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 7.27e-7 AC: 1 AN: 1376034 Hom.: 0 Cov.: 37 AF XY: 0.00000146 AC XY: 1 AN XY: 682952

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000118

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Tuberous sclerosis 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 28, 2023

This sequence change replaces leucine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 896 of the TSC1 protein (p.Leu896Phe). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TSC1-related conditions. ClinVar contains an entry for this variant (Variation ID: 578105). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt TSC1 protein function with a negative predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Uncertain	0.014	T
BayesDel_noAF	Benign	-0.22
CADD	Benign	23
DANN	Uncertain	0.99
DEOGEN2	Benign	0.41	T;.;T;.;.;T;.;T;.;.;.
Eigen	Uncertain	0.32
Eigen_PC	Uncertain	0.33
FATHMM_MKL	Pathogenic	0.98	D
M_CAP	Uncertain	0.11	D
MetaRNN	Benign	0.27	T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Uncertain	0.27	D
MutationAssessor	Benign	1.7	L;.;L;.;.;L;.;L;.;.;.
MutationTaster	Benign	0.99	D;D;D;D
PrimateAI	Benign	0.45	T
PROVEAN	Benign	-0.83	N;N;N;.;.;.;.;.;.;.;.
REVEL	Uncertain	0.39
Sift	Benign	0.36	T;T;T;.;.;.;.;.;.;.;.
Sift4G	Uncertain	0.023	D;D;D;.;.;.;.;.;.;.;.
Polyphen		0.82	P;.;P;.;.;P;.;P;.;.;.
Vest4		0.48
MutPred		0.16		Loss of MoRF binding (P = 0.1886);.;Loss of MoRF binding (P = 0.1886);.;.;Loss of MoRF binding (P = 0.1886);.;Loss of MoRF binding (P = 0.1886);.;.;.;
MVP		0.49
MPC		0.61
ClinPred		0.66	D
GERP RS		4.7
Varity_R		0.22
gMVP		0.057

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: rs377132822; hg19: chr9-135772937;