Objective: Branched-chain organic acidemias (OAs) are inherited metabolic disorders resulting from enzyme deficiencies in the catabolic pathway of branched-chain amino acids, which could lead to mitochondrial dysfunction and oxidative stress. This study aimed to evaluate oxidative stress in OA patients using thiol-disulfide homeostasis (TDH) parameters.

Methods: 21 OA patients [methylmalonic acidemia (MMA), propionic acidemia (PA), and isovaleric acidemia] and 12 healthy controls participated in this study. TDH parameters such as native thiol, total thiol, and disulfide levels, in addition to Oxidative Stress Index, Total Antioxidant Status, and Total Oxidant Status were analyzed using spectrophotometry.

Results: The OA group had significantly lower native (p=0.004) and total thiol (p=0.006) levels compared to controls. When analyzing subgroups, native thiols were found to be lower in MMA (p=0.012) and in PA (p=0.008) with elevated disulfides in MMA (p=0.003) in comparison to both PA and controls. As compared to abnormal neurodevelopmental status, there was a statistically significant relationship with lower native thiols and a shift towards oxidative stress (p=0.004).

Conclusions: The parameters of the TDH are altered in patients with OA, especially in those with MMA and PA, indicating a significant level of oxidative stress. The neurodevelopmental outcome in OA may be exacerbated by this oxidative imbalance. The utilization of TDH as a biomarker may be a potential provider of oxidative status in OA patients and facilitate informing therapeutic strategies.