Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM2PM5PP3_StrongPP5_Moderate
The NM_000368.5(TSC1):c.913G>C(p.Gly305Arg) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely pathogenic in Lovd. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G305W) has been classified as Pathogenic.
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]
Verdict is Pathogenic. Variant got 10 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
PM5
Other missense variant is known to change same aminoacid residue: Variant chr9-132912282-C-A is described in Lovd as [Pathogenic].
PP3
Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
PP5
Variant 9-132912282-C-G is Pathogenic according to our data. Variant chr9-132912282-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2636244.Status of the report is criteria_provided_single_submitter, 1 stars.
Review Status: criteria provided, single submitter
Collection Method: clinical testing
The TSC1 c.913G>C variant is predicted to result in the amino acid substitution p.Gly305Arg. This variant occurs at the last nucleotide of exon 9 and is predicted to alter splicing based on available splicing prediction programs (Alamut Visual v2.11). However, the use of computer prediction programs is not equivalent to functional evidence. To our knowledge, this variant has not been reported in the literature or in a large population database (http://gnomad.broadinstitute.org), indicating this variant is rare. This variant has been confirmed de novo in an individual undergoing tuberous sclerosis panel testing (Internal Data, PreventionGenetics). This variant is interpreted as likely pathogenic. -