Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2PP3_Strong
The NM_001278646.2(NDUFB9):c.-127A>T variant causes a 5 prime UTR premature start codon gain change. The variant allele was found at a frequency of 0.00000205 in 1,461,854 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.
NDUFB9 (HGNC:7704): (NADH:ubiquinone oxidoreductase subunit B9) The protein encoded by this gene is a subunit of the mitochondrial oxidative phosphorylation complex I (nicotinamide adenine dinucleotide: ubiquinone oxidoreductase). Complex I is localized to the inner mitochondrial membrane and functions to dehydrogenate nicotinamide adenine dinucleotide and to shuttle electrons to coenzyme Q. Complex I deficiency is the most common defect found in oxidative phosphorylation disorders and results in a range of conditions, including lethal neonatal disease, hypertrophic cardiomyopathy, liver disease, and adult-onset neurodegenerative disorders. Pseudogenes of this gene are found on chromosomes five, seven and eight. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2015]
TATDN1 (HGNC:24220): (TatD DNase domain containing 1) Predicted to enable 3'-5'-exodeoxyribonuclease activity. Predicted to be involved in DNA metabolic process and nucleic acid phosphodiester bond hydrolysis. Located in nucleoplasm. [provided by Alliance of Genome Resources, Apr 2022]