A recent study has shown that zebrafish consists of two orthologs, mcoln1a and mcoln1b, of MCOLN1, and mcoln1ab double-mutant zebrafish display retinal and neuromuscular defects similar to the patients with ML-IV with MCOLN1 deficiency (Folkerth et al., 1995, Li et al., 2017, Wakabayashi et al., 2011). The gene discussed is MCOLN1; the disease is mucolipidosis type IV.