Whole-exome sequencing in a female fetus detected a USP9X variant. This X-linked gene was recently associated with intellectual disability and distinct pattern of malformation in females. Isolated agenesis of the corpus callosum has not been reported in association with USP9X. Identifying this variant impacted management of the subsequent pregnancy.

Whole exome sequencing (WES) was used to determine the etiology of recurrent hydrops fetalis in this case of Hennekam lymphangiectasia-lymphedema syndrome-1. WES is a useful approach for diagnosing rare single-gene conditions with nonspecific phenotypes and should be considered early in the diagnostic process of investigating fetal abnormalities.