Rare disease specialist Ultragenyx Pharmaceutical Inc. has agreed to pay $20 million for an exclusive option to acquire Genetx Biotherapeutics LLC, the developer of a University of Texas-sourced antisense oligonucleotide for the potential treatment of Angelman syndrome, GTX-102. An IND for the asset, now in late preclinical development, is expected to be filed with the FDA in the first half of 2020.