NANS and skeletal dysplasia: Confirmation of high levels of this enzymatic substrate of NANS suggested that the clinical phenotype was likely caused by an enzymatic deficiency in NANS. Normalization of skeletal dysplasia in a zebrafish model with knocked-out nansa and nansb (zebrafish orthologs for human NANS) occurred after supplementation with sialic acid, shedding light on a possible treatment.