Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2PM4_SupportingPP3PP5_Moderate
The NM_018486.3(HDAC8):c.839_843delCTCCAinsGT(p.Thr280_Pro281delinsSer) variant causes a missense, disruptive inframe deletion change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★).
HDAC8 (HGNC:13315): (histone deacetylase 8) Histones play a critical role in transcriptional regulation, cell cycle progression, and developmental events. Histone acetylation/deacetylation alters chromosome structure and affects transcription factor access to DNA. The protein encoded by this gene belongs to class I of the histone deacetylase family. It catalyzes the deacetylation of lysine residues in the histone N-terminal tails and represses transcription in large multiprotein complexes with transcriptional co-repressors. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2009]
Verdict is Likely_pathogenic. Variant got 6 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
PM4
Nonframeshift variant in NON repetitive region in NM_018486.3. Strenght limited to Supporting due to length of the change: 1aa.
PP3
No computational evidence supports a deleterious effect, but strongly conserved according to phyloP
PP5
Variant X-72464626-TGGAG-AC is Pathogenic according to our data. Variant chrX-72464626-TGGAG-AC is described in ClinVar as [Likely_pathogenic]. Clinvar id is 369669.Status of the report is criteria_provided_single_submitter, 1 stars.
Victorian Clinical Genetics Services, Murdoch Childrens Research Institute
Significance: Likely pathogenic
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This deletion of 5 residues and insertion of two residues is predicted to result in a substitution of threonine for a serine at position 280, and a deletion of a proline at position 281. The amino acids at these positions are highly conserved. MutationTaster predicts this deletion to be deleterirous. Both amino acids are located in teh histone deacetylase domain in close proximity to the active site. This varaint is novel, and was found to be de novo on parental testing. -