title: An unbalanced translocation 46,XX,+der(18)t(18;21)(q12.2;q11.2)mat,-21 associated with maternal isodisomy 18pter-->18q12.2.
abstract: We report a patient with a 46,XX,+der(18)t(18;21)(q12.2;q11.2)mat,-21 karyotype, in whom the rarely seen adjacent-2 segregation (according to the predicted pachytene diagram model) as well as two cross-overs, resulted in maternal isodisomy 18pter-->18q12.2.
authors.affiliation: Centre for Human Genetics, KULeuven, UZ Gasthuisberg, Herestraat 49, B3000, Leuven, Belgium.
authors.forename: T J
authors.initials: TJ
authors.lastname: de Ravel
authors.forename: G
authors.initials: G
authors.lastname: Matthijs
authors.forename: J
authors.initials: J
authors.lastname: Fryns
mesh_terms: D000015:Abnormalities, Multiple / Q000235:genetics*; D002503:Centromere / Q000235:genetics; D002675:Child, Preschool; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics*; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D003434:Crossing Over, Genetic / Q000235:genetics; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D010641:Phenotype; D011110:Polymorphism, Genetic / Q000235:genetics; D014178:Translocation, Genetic / Q000235:genetics*; D024182:Uniparental Disomy / Q000235:genetics*