title: Small supernumerary chromosome marker generating complete and pure trisomy 18p, characterized by molecular cytogenetic techniques and review.
abstract: Small supernumerary marker chromosomes (sSMC) have been described from all human chromosomes with different sizes and shapes. However, it is difficult to know the clinical manifestations associated with them, because such knowledge depends on the size, presence of euchromatic material, degree of mosaicism and/or uniparental disomy (UPD). Pure trisomy of the whole arm of chromosome 18 (18p), has been described in only a few cases and the general consensus is that there is a mild phenotypic effect. Here we report on a newborn male presenting with an atrial septal defect and a club foot. The high resolution G-band karyotype (550-850 bands) and the molecular cytogenetic techniques revealed in all cells the presence of an sSMC, which was a complex derivative from the short arm of a chromosome 18 (18p) and a centromere of a chromosome 13/21. His healthy mother had the same sSMC in all analyzed cells. With the present case, we support the previous suggestion that this unusual chromosome trisomy 18p has little clinical repercussions.
authors.affiliation: Estudio Colaborativo Español de Malformaciones Congénitas del Centro de Investigación sobre Anomalías Congénitas, Instituto de Salud Carlos III, Ministerio de Sanidad y Consumo, Madrid, Spain. laura@isciii.es
authors.forename: L
authors.initials: L
authors.lastname: Rodríguez
authors.forename: T
authors.initials: T
authors.lastname: Liehr
authors.forename: K
authors.initials: K
authors.lastname: Mrasek
authors.forename: E
authors.initials: E
authors.lastname: Mansilla
authors.forename: M L
authors.initials: ML
authors.lastname: Martínez-Fernández
authors.forename: A
authors.initials: A
authors.lastname: Garcia
authors.forename: M L
authors.initials: ML
authors.lastname: Martínez-Frías
mesh_terms: D002887:Chromosomes, Human, Pair 18; D020732:Cytogenetic Analysis; D005819:Genetic Markers; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D014314:Trisomy; D024182:Uniparental Disomy
chemical_list: D005819:Genetic Markers