Megaloblastic anemia is often observed in the neonatal forms of intracellular Cbl defects (cblF, cblJ, cblC, cblD-MMA/Hcy, cblD-HC, cblE, and cblG) but less frequently in the late-onset forms of these disorders (Table 2) [8,9]. This evidence concerns the gene MMADHC and megaloblastic anemia.