UNIPARENTAL DISOMY (UPD)

Uniparental disomy is the inheritance of both chromosomes of a set from one parent.

It is now well recognized as a non-Mendelian cause of genetic abnormalities.

It has been well established for chromosomes 6, 7, 11, 14, and 15.

Paternal UPD 6	Transient neonatal diabetes
Maternal UPD 7	Russell Silver syndrome
Paternal UPD 11p15.5	Beckwith-Wiedermann syndrome
Maternal UPD 14 Paternal UPD 14	Fetal and post-natal growth restriction; minor dysmorphic features; postnatal hypotonia with motor delay; precocious puberty. Small thorax; larygomalacia; ventral wall hernia; short limbs; joint contractures; craniofacial dysmorphia; mental retardation; increased nuchal translucency.
Maternal UPD 15 Paternal UPD 15	Prader-Willi syndrome Angelman syndrome

REFERENCES

1. Kotzot D. Abnormal phenotypes in uniparental disomy (UPD): Fundamental aspects and critical review with bibliography of UPD other than 15. Am J Med Genet 1999;82:265-274.
2. Robinson WP. Mechanisms leading to uniparental disomy and other clinical consequences. Bioessays 2000;22:452-454.
3. Healy S, Powell F, Battersby M et.al. Distinct phenotype in maternal uniparental disomy of chromosome 14. Am J Med Genet 1994;51:147-149.
4. Sutton VR, Shaffer LG. Search for imprinted regions on chromosome 14; Comparison of maternal and paternal UPD cases with cases with case of chromosome 14 deetion. Am J Med Genet 2000;93:381-387.
5. Schaffer LG, McCaskill C, Adkins K et.al. Systematic search for uniparental disomy in early fetal loss: The results and a review of the literature. Am J Med Genet 1998;79:366-372.
6. Towner D, Yang SP, Shaffer LG. Prenatal ultrasound findings in a fetus with paternal uniparental disomy 14q12-qter. Ultrasound Obstet Gynecol 2001;18:268-271.