title: Maternal uniparental isodisomy 20 in a foetus with trisomy 20 mosaicism: clinical, cytogenetic and molecular analysis.
abstract: The clinical significance of trisomy 20 mosaicism detected prenatally remains uncertain due to the rarity of liveborn cases with inconsistent clinical findings, and lack of long-term follow-up and outcome. We describe a case of true trisomy 20 mosaicism in a liveborn girl with maternal uniparental isodisomy of chromosome 20 in the diploid blood cells. Trisomy 20 mosaicism was originally detected in amniotic fluid (98%) and was confirmed in the term placenta (100%), as well as in the blood (10%) and urine sediment (100%) of the neonate. There was intrauterine and postnatal growth retardation, but otherwise the newborn manifested no gross abnormalities. At 9 months of age moderate psychomotor retardation, central hypotonia with peripheral hypertonia, numerous minor morphogenetic variants, marked kyphosis, and extensive Mongolian spot were observed. To our knowledge this represents the first case of trisomy 20 mosaicism detected prenatally and confirmed in different tissues of the newborn, where uniparental disomy was demonstrated in the diploid cell line. The clinical and laboratory findings in our patient are compared with those of five previously reported cases of UPD20, suggesting that maternal UPD20 might be associated with a characteristic phenotype.
authors.affiliation: Cytogenetics Laboratory, Department of Genetics and Molecular Biology, Mitera Maternity and Surgical Center, Athens, Greece.
authors.forename: Voula
authors.initials: V
authors.lastname: Velissariou
authors.forename: Thalia
authors.initials: T
authors.lastname: Antoniadi
authors.forename: Jolanda
authors.initials: J
authors.lastname: Gyftodimou
authors.forename: Katerina
authors.initials: K
authors.lastname: Bakou
authors.forename: Maria
authors.initials: M
authors.lastname: Grigoriadou
authors.forename: Stavroula
authors.initials: S
authors.lastname: Christopoulou
authors.forename: Athina
authors.initials: A
authors.lastname: Hatzipouliou
authors.forename: Jackie
authors.initials: J
authors.lastname: Donoghue
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Karatzis
authors.forename: Efstathia
authors.initials: E
authors.lastname: Katsarou
authors.forename: Michael B
authors.initials: MB
authors.lastname: Petersen
mesh_terms: D002890:Chromosomes, Human, Pair 20; D005260:Female; D005819:Genetic Markers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007231:Infant, Newborn; D009030:Mosaicism; D011596:Psychomotor Disorders / Q000209:etiology / Q000235:genetics; D014314:Trisomy; D024182:Uniparental Disomy
chemical_list: D005819:Genetic Markers