SLC3A1 and hypotonia-cystinuria syndrome: Hypotonia-cystinuria syndrome has been described as a disorder with cystinuria and congenital myasthenic result from the recessive deletions in SLC3A1 and PREPL (Jaeken et al., 2006; Régal et al., 2014; Legati et al., 2016; Tucker et al., 2019).