Rebecca Foulger commented on gene: EXT2: PMID:30997052. In a 14 year old girl, Gupta et al. (2019) identified compound het missense variants in the EXT2 gene (V373D and T672M), which segregated with the disorder in the family. The patient also carried a maternal heterozygous variant (R454C) in NDST1. She had developmental delay, autism and epilepsy amongst her phenotypes.