ST3GAL5 and Global developmental delay: We observed that both R288X and non-R288X patients exhibited psychomotor delay, microcephaly, epilepsy, dystonia/movement disorder, sit or walk independently, developmental stagnation/failure to thrive, development delay, hearing impairment, vision impairment, abnormal pigmentation, irritability, feeding difficulties, gastrostomy feeding tube, scoliosis, and abnormal electroencephalographic These may stem from GM3 synthase deficiency, leading to a deficit in several gangliosides, including GM3, common in both R288X and non-R288X patients.