Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1PM2PM5PP3_Strong
The NM_000548.5(TSC2):c.4949A>C(p.Tyr1650Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic 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. Y1650N) has been classified as Uncertain significance.
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]
Verdict is Pathogenic. Variant got 10 ACMG points.
PM1
In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 8 benign, 15 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 chr16-2086831-A-G is described in Lovd as [Pathogenic].
PP3
MetaRNN computational evidence supports a deleterious effect, 0.992
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change replaces tyrosine, which is neutral and polar, with serine, which is neutral and polar, at codon 1650 of the TSC2 protein (p.Tyr1650Ser). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TSC2-related conditions. 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 expected to disrupt TSC2 protein function. 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. -