Maternal heterodisomy and isodisomy (>28 cases in literature) is associated with a characteristic phenotype similar to that of Prader-Willi syndrome (hypotonia, motor developmental delay, mild dysmorphic facial features, low birth weight, growth abnormalities (precocious puberty) (Kamnasaran D et al. 2001; Ledbetter DH et al. 1995; Hurst LD et al. 1997; Tomkins DJ et al. 1996; Kotzot D, 2007; Kagami M et al, 2008; Ogata T et al, 2008; Aretz S et al, 2005; Hosoki K et al, 2009).

Paternal isodisomy or heterodisomy of chromosome 14 (at least 17 cases) is associated with severe mental and musculoskeletal phenotype (Stevenson DA et al, 2004; Kurosawa K et al. 2002; Kamnasaran D et al. 2001; Walter CA et al. 1996; Cotter PD et al. 1997; Ogata T et al, 2008) which is recapitulated in paternal UPD of mouse chromosome 12.
Analysis of UPD14 cases suggests that imprinted genes on 14q32 are responsible for the phenotypes, but also that other imprinted regions on chr14 may exist (Kotzot D et al. 2001 for a review see Kotzot et al 2004; Sutton VR et al. 2000).

A patient with clinical features of maternal UPD14, including growth retardation, hypotonia, scoliosis, small hands and feet, and advanced puberty, had loss of methylation of the IG-DMR but no evidence of maternal UPD14 (Temple IK et al, 2007). This case suggests that the maternal UPD14 phenotype is due to aberrant gene expression within the imprinted domain at 14q32.
Quantitative real-time PCR showed that RTL1 expression level was about five times higher in the placental samples of two patients with paternal uniparental disomy 14 compared to controls, consistent with paternal expression (Kagami M et al, 2012).


Disomy (UPD)



Last Modified 10/27/2012


*To look at further records use the Back button on your browser to return to the Summary Table

New Search