Ganglioside GM3 synthase is a key enzyme involved in the biosynthesis of gangliosides. GM3 synthase deficiency (GM3D) causes an absence of GM3 and all downstream biosynthetic derivatives. The affected individuals manifest with severe irritability, intractable seizures, and profound intellectual disability. The current study is to assess the effects of an oral ganglioside supplement to patients with GM3D, particularly on their growth and development during early childhood. A total of 13 young children, 11 of them under 40 months old, received oral ganglioside supplement through a dairy product enriched in gangliosides, for an average of 34 months. Clinical improvements were observed in most children soon after the supplement was initiated. Significantly improved growth and development were documented in these subjects as average percentiles for weight, height, and occipitofrontal circumference increased in 1-2 months. Three children with initial microcephaly demonstrated significant catch-up head growth and became normocephalic. We also illustrated brief improvements in developmental and cognitive scores, particularly in communication and socialization domains through Vineland-II. However, all improvements seemed transient and gradually phased out after 12 months of supplementation. Gangliosides GM1 and GM3, although measureable in plasma during the study, were not significantly changed with ganglioside supplementation for up to 30 months. We speculate that the downstream metabolism of ganglioside biosynthesis is fairly active and the potential need for gangliosides in the human body is likely substantial. As we search for new effective therapies for GM3D, approaches to reestablish endogenous ganglioside supplies in the affected individuals should be considered.
Keywords: Ganglioside GM3 synthase deficiency; ST3GAL5; Treatment.