Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2
The NM_012123.4(MTO1):c.1291C>T(p.Arg431Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,888 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R431Q) has been classified as Uncertain significance.
MTO1 (HGNC:19261): (mitochondrial tRNA translation optimization 1) This gene encodes a mitochondrial protein thought to be involved in mitochondrial tRNA modification. The encoded protein may also play a role in the expression of the non-syndromic and aminoglycoside-induced deafness phenotypes associated with a specific mutation in the mitochondrial 12S rRNA gene. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]
Mitochondrial hypertrophic cardiomyopathy with lactic acidosis due to MTO1 deficiency Uncertain:1
Sep 01, 2021
Labcorp Genetics (formerly Invitae), Labcorp
Significance: Uncertain significance
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change replaces arginine with tryptophan at codon 431 of the MTO1 protein (p.Arg431Trp). The arginine residue is moderately conserved and there is a moderate physicochemical difference between arginine and tryptophan. This variant has not been reported in the literature in individuals affected with MTO1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0"). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -