Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2PM4
The NM_000368.5(TSC1):c.1289_1290insGCGCGGACC(p.Pro430_Cys431insArgGlyPro) variant causes a disruptive inframe insertion change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).
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]
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This variant, c.1289_1290insGCGCGGACC, results in the insertion of 3 amino acid(s) to the TSC1 protein (p.Pro430_Cys431insArgGlyPro), but otherwise preserves the integrity of the reading frame. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with TSC1-related disease. Experimental studies and prediction algorithms are not available for this variant, and the functional significance of the duplicated amino acids is currently unknown. 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. -