Sdha, short for succinate dehydrogenase subunit A, is a key component of the succinate dehydrogenase complex. This complex is involved in the tricarboxylic acid (TCA) cycle and mitochondrial respiratory chain, playing a crucial role in cellular energy metabolism [1,2,3,4,5,6,7].

Loss-of-function of the succinate dehydrogenase complex is seen in 20-40% of all KIT/PDGFRA-negative gastrointestinal stromal tumors (GISTs). Among SDH-deficient GISTs, SDHA mutations are the most common (30%), leading to loss of SDHA and SDHB protein expression [1]. SDHA pathogenic germline variants (PGVs) are identified in up to 10% of patients with paraganglioma and phaeochromocytoma and up to 30% with wild-type GISTs [2]. In phaeochromocytomas and paragangliomas, SDHA PVs account for up to 2.8% of cases, with tumors often presenting as single ones, commonly in the head and neck or abdomen, and a 25.5% metastasis rate [3]. In hepatocellular carcinoma, downregulation of SDHA/B is observed, promoting cancer proliferation by stabilizing YAP/TAZ [4]. In diabetic cardiomyopathy, CAV1 binds with SDHA, triggering its ubiquitination and degradation, resulting in mitochondrial dysfunction, which can be alleviated by LNT [6]. In primary antibody deficiency, SDHA gain-of-function leads to fumarate accumulation, engaging the KEAP1-Nrf2 system to drive inflammatory cytokine transcription [7].

In conclusion, Sdha is essential for normal cellular energy metabolism. Its dysregulation, as revealed through various disease-related studies rather than KO/CKO mouse models in the provided references, is associated with multiple diseases including GISTs, paraganglioma, phaeochromocytoma, hepatocellular carcinoma, diabetic cardiomyopathy, and primary antibody deficiency. Understanding Sdha's role in these conditions may provide insights for disease management and treatment.