title: Replication error, a new hypothesis to explain the origin of a supernumerary marker chromosome in a mentally retarded boy.
abstract: A marker chromosome present in all the lymphocytes of a mentally retarded boy (47,XY,+mar) was identified. The karyotype of all fibroblasts was normal, 46,XY. His parents had normal karyotypes. The supernumerary marker chromosome was interpreted as a dicentric palindromic chromosome iso(9) (pter----q12, q12----pter). The marker chromosome may have originated through a ligation error in a replication fork during the S-phase followed by a new replication (endoreduplication).
authors.forename: A
authors.initials: A
authors.lastname: Wik Sjöstedt
authors.forename: M
authors.initials: M
authors.lastname: Alatalo
authors.forename: J
authors.initials: J
authors.lastname: Wahlström
authors.forename: U
authors.initials: U
authors.lastname: von Döbeln
authors.forename: R
authors.initials: R
authors.lastname: Olegård
mesh_terms: D002675:Child, Preschool; D002869:Chromosome Aberrations / Q000235:genetics*; D002899:Chromosomes, Human, Pair 9 / Q000648:ultrastructure; D004261:DNA Replication / Q000502:physiology; D005819:Genetic Markers; D006801:Humans; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000235:genetics*; D007621:Karyotyping; D008297:Male
chemical_list: D005819:Genetic Markers