Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2PM5PP2PP3_Moderate
The NM_000368.5(TSC1):āc.227T>Gā(p.Ile76Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,232 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I76N) has been classified 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]
Verdict is Likely_pathogenic. Variant got 7 ACMG points.
PM2
?
PM2 - Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium
Very rare variant in population databases, with high coverage;
PM5
?
PM5 - Novel missense change at an amino acid residue where a different missense change determined to be pathogenic has been seen before
Other missense variant is known to change same aminoacid residue: Variant chr9-132925723-A-T is described in Lovd as [Pathogenic].
PP2
?
PP2 - Missense variant in a gene that has a low rate of benign missense variation and in which missense variants are a common mechanism of disease
Missense variant where missense usually causes diseases, TSC1
PP3
?
PP3 - Multiple lines of computational evidence support a deleterious effect on the gene or gene product (conservation, evolutionary, splicing impact, etc.)
MetaRNN computational evidence supports a deleterious effect, 0.922
Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);Gain of disorder (P = 0.002);