Genes encoding HS-modifying enzymes include NDST3 implicated in schizophrenia by a genome-wide association study supported by expression profiling, NDST1 in which a compound heterozygous mutation was found in developmental delay, and HS3ST5 associated with autism (Armstrong et al., 2017, Lencz et al., 2013, Wang et al., 2009). The gene discussed is NDST1; the disease is Global developmental delay.