Cases of maternal UPD of chromosome 21 have been reported in healthy individuals. This suggests no phenotypically
important imprinted genes are located on maternal chromosome 21 (Mansuet-Lupo A et al 2009; Rogan PK et al 1999).
One case of maternal UPD of chromosome 21 leading to a recessive disorder has been reported. In this case the UPD
lead to Bartsocas-Papas syndrome (BPS), a severe form of popliteal pterygia, characterised by cutaneous webbing
across joints, cleft lip and/or palate, syndactyly and genital malformations (Leslie EJ et al 2015).
A case of paternal UPD of chromosome 21 has been identified in a healthy individual (Blouin JL et al 1993).