In the case of the 14-year-old girl with hearing loss and elevated lactic acid levels, which genetic mutation is most likely present?

The scenario presents a 14-year-old girl with hearing loss and elevated lactic acid levels, suggesting a mitochondrial disorder, as hearing loss can be associated with mitochondrial dysfunction due to the high energy demand of the auditory system. Elevated lactic acid indicates an issue with aerobic metabolism, which aligns with mitochondrial dysfunction since these organelles are crucial for ATP production through oxidative phosphorylation.

The mutation in mitochondrial tRNA Leu is associated with various mitochondrial diseases, which can present with symptoms such as hearing loss, lactic acidosis, and myopathies. Mutations affecting mitochondrial tRNA can disrupt protein synthesis within the mitochondria, leading to impaired function of the respiratory chain complexes and subsequently increased lactate production. This aligns well with the clinical presentation of the girl.

Other mutations listed involve different biochemical pathways and organelles. Endoplasmic reticulum glycosyltransferase mutations typically lead to disorders affecting glycosylation, which may not directly present with the characteristics noted in this case. Lysosomal a-glucosidase deficiency is related to Pompe disease, primarily affecting muscle function rather than directly causing hearing loss or lactic acidosis unless in more severe cases. The nuclear proteasome activator is involved in protein degradation and thus does not directly correlate with mitochondrial