PDS5B is a sister chromatid cohesion protein that is crucial for faithful 
segregation of duplicated chromosomes in lower organisms. Mutations in cohesion 
proteins are associated with the developmental disorder Cornelia de Lange 
syndrome (CdLS) in humans. To delineate the physiological roles of PDS5B in 
mammals, we generated mice lacking PDS5B (APRIN). Pds5B-deficient mice died 
shortly after birth. They exhibited multiple congenital anomalies, including 
heart defects, cleft palate, fusion of the ribs, short limbs, distal colon 
aganglionosis, abnormal migration and axonal projections of sympathetic neurons, 
and germ cell depletion, many of which are similar to abnormalities found in 
humans with CdLS. Unexpectedly, we found no cohesion defects in Pds5B(-/-) cells 
and detected high PDS5B expression in post-mitotic neurons in the brain. These 
results, along with the developmental anomalies of Pds5B(-/-) mice, the presence 
of a DNA-binding domain in PDS5B in vertebrates and its nucleolar localization, 
suggest that PDS5B and the cohesin complex have important functions beyond their 
role in chromosomal dynamics.