Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM2PM5BP6
The NM_000548.5(TSC2):āc.991A>Gā(p.Asn331Asp) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,774 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N331K) has been classified 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 Uncertain_significance. Variant got 3 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
PM5
Other missense variant is known to change same aminoacid residue: Variant chr16-2060687-C-A is described in Lovd as [Pathogenic].
BP6
Variant 16-2060685-A-G is Benign according to our data. Variant chr16-2060685-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 406128.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=1, Benign=1}.
Uncertain significance, criteria provided, single submitter
clinical testing
Ambry Genetics
Nov 21, 2024
The p.N331D variant (also known as c.991A>G), located in coding exon 10 of the TSC2 gene, results from an A to G substitution at nucleotide position 991. The asparagine at codon 331 is replaced by aspartic acid, an amino acid with highly similar properties. This amino acid position is conserved. In addition, the in silico prediction for this alteration is inconclusive. Based on the available evidence, the clinical significance of this variant remains unclear. -
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