Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PS1PM2PM5PP3_StrongPP5_Moderate
The ENST00000403810.6(TSC1):c.1030G>C(p.Val344Leu) variant causes a missense change. 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 Pathogenic (★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Pathogenic in Lovd. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V344I) has been classified as Likely 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 14 ACMG points.
PS1
Transcript ENST00000403810.6 (TSC1) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in Lovd
PM2
Very rare variant in population databases, with high coverage;
PM5
Other missense variant is known to change same aminoacid residue: Variant chr9-132911452-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 48729.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
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 9-132911452-C-G is Pathogenic according to our data. Variant chr9-132911452-C-G is described in ClinVar as [Pathogenic]. Clinvar id is 1409199.Status of the report is criteria_provided_single_submitter, 1 stars.
Review Status: criteria provided, single submitter
Collection Method: clinical testing
For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. This sequence change affects a donor splice site in intron 10 of the TSC1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in TSC1 are known to be pathogenic (PMID: 10227394, 17304050). This variant is not present in population databases (ExAC no frequency). Disruption of this splice site has been observed in individual(s) with tuberous sclerosis complex (PMID: 32211034, 9328481). In at least one individual the variant was observed to be de novo. -