BBOX1 and systemic primary carnitine deficiency disease: In addition, while inhibiting the absorption of carnitine, THP simultaneously competes with γ-butyrobetaine (γ-BB) for γ-butyrobetaine hydroxylase (BBOX) binding to inhibit carnitine endogenous synthesis, thus, exacerbating the carnitine deficiency and promoting the formation of liver steatosis [18].