P165: Expanded molecular newborn screening: Comparing results of a 256 vs 1,518 gene panel*

Conclusion: Both the depleted and reduced mtDNA content categories contained diagnoses of primary mtDNA disorder, while the depleted mtDNA category having the highest diagnosis yield, although sample size (n=8) was small.Diagnoses in the normal mtDNA content category were generally unrelated to primary mtDNA disorders.MtDNA content analysis is a valuable tool for screening MDS and has proven effective in identifying cases for further genetic work-up.Besides the individuals with confirmed genetic diagnoses, a considerable number were found to have variants of uncertain significance (VOUS) in mitochondrial genes or candidate genes.As variant classification may evolve over time, further review of these data is warranted and may enhance our standing of these conditions.