CBS and homocystinuria: Besides, from cblC type MMA, there are many genetic disorders with a high incidence and hotspot mutations in specific population, such as c.1006C > T mutation in CBS gene mutation of homocystinuria in Qatar (El-Said et al., 2006; Al-Dewik et al., 2019), and c.394C > T mutation in MMACHC gene cobalamin C defect in North India (Kaur et al., 2021).