Paired bo, Xenopus/Amphibian, protein Pa, Xenopus/Amphibian,-2 (Pa, Xenopus/Amphibian,-2) is a transcription factor that has a role in kidney cell differentiation. Pa, Xenopus/Amphibian,-2 has a critical role in the development of the urogenital tract, the eyes, and the CNS. Defects in Pa, Xenopus/Amphibian,-2 are responsible for isolated renal hypoplasia as observed in oligomeganephronia, a rare congenital and usually sporadic anomaly characterized by bilateral renal hypoplasia, with a reduced number of enlarged nephrons and without urinary tract abnormalities.