Ganglioside GM3 synthase deficiency is a rare autosomal recessive infantile-onset symptomatic epilepsy syndrome associated with developmental stagnation and cortical blindness. A homozygous nonsense variant, c.862C>T (p.Arg288*), was identified in the ST3GAL5 gene of a large Old Order Amish family. Affected children completely lack GM3 and its downstream biosynthetic derivatives but have increased levels of the immediate precursor to GM3, lactosylceramide. This targeted test will specifically analyze the c.862C>T pathogenic variant in the Old Order Amish population.
1 - 2 weeks