OTC and Alexander disease: For instance, between 2014 to 2015, the following diseases had more than one reported case in China: isovaleric acidemia [16–18], ornithine transcarbamylase deficiency [19, 20], glutaric acidemia type I [21, 22], leukoencephalopathy with calcifications and cysts [23, 24], Alexander disease [25–28], myoclonic epilepsy with ragged red fibers [29, 30], and Pelizaeus–Merzbacher disease [31].