Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_ModeratePM2PP5_Very_Strong
The NM_000548.5(TSC2):c.1257+1G>A variant causes a splice donor, intron 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. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).
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 12 ACMG points.
PVS1
Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.025442477 fraction of the gene. Cryptic splice site detected, with MaxEntScore 3.4, offset of 40, new splice context is: ctgGTgggg. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
PM2
Very rare variant in population databases, with high coverage;
PP5
Variant 16-2062009-G-A is Pathogenic according to our data. Variant chr16-2062009-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 65089.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-2062009-G-A is described in Lovd as [Pathogenic]. Variant chr16-2062009-G-A is described in Lovd as [Pathogenic].
Center for Human Genetics, Inc, Center for Human Genetics, Inc
Significance: Pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing
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Nov 07, 2021
Genome-Nilou Lab
Significance: Pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing
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Feb 01, 2020
Molecular Biology Laboratory, Fundació Puigvert
Significance: Pathogenic
Review Status: criteria provided, single submitter
Collection Method: research
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May 05, 2023
Labcorp Genetics (formerly Invitae), Labcorp
Significance: Pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change affects a donor splice site in intron 12 of the TSC2 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 TSC2 are known to be pathogenic (PMID: 10205261, 17304050). This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individual(s) with tuberous sclerosis complex (PMID: 28623545). ClinVar contains an entry for this variant (Variation ID: 65089). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -