SLC22A5 and systemic primary carnitine deficiency disease: However, carnitine could be used as dietary supplements to help with carnitine shuttle of FAO in conditions of “primary carnitine deficiency” (children with genetic disorder of carnitine transporter OCTN2 encoded by the SLC22A5 gene; Frigeni et al., 2017) or adults with secondary carnitine deficiencies due to chronic renal failure (Ames, 2010).