This family consists of several eukaryotic succinate dehydrogenase [ubiquinone] cytochrome B small subunit, mitochondrial precursor (CybS) proteins. SDHD encodes the small subunit (cybS) of cytochrome b in succinate-ubiquinone oxidoreductase (mitochondrial complex II). Mitochondrial complex II is involved in the Krebs cycle and in the aerobic electron transport chain. It contains four proteins. The catalytic core consists of a flavoprotein and an iron-sulfur protein; these proteins are anchored to the mitochondrial inner membrane by the large subunit of cytochrome b (cybL) and cybS, which together comprise the heme-protein cytochrome b. Mutations in the SDHD gene can lead to hereditary paraganglioma, characterised by the development of benign, vascularised tumours in the head and neck [1].

1: Mutations in SDHD, a mitochondrial complex II gene, in hereditary paraganglioma. Baysal BE, Ferrell RE, Willett-Brozick JE, Lawrence EC, Myssiorek D, Bosch A, van der Mey A, Taschner PE, Rubinstein WS, Myers EN, Richard CW 3rd, Cornelisse CJ, Devilee P, Devlin B; Science 2000;287:848-851. PMID:10657297