title: Mosaic trisomy (8)(p22 --> pter) in a fetus caused by a supernumerary marker chromosome without alphoid sequences.
abstract: OBJECTIVE
  Our objective was to characterise a marker chromosome in cultured amniocytes of a fetus with a mos 47,XX,+mar[3]/46,XX[14] karyotype.
  
  
  METHODS
  The indication for prenatal cytogenetic analysis of cultured amniocytes was advanced maternal age. Classic banding techniques (GTG- and C-banding) were performed. Microdissection combined with reverse painting was used to disclose the exact origin of the marker; the result was confirmed by chromosome painting and FISH with band-specific probes.
  
  
  RESULTS
  Analysis of GTG-banded chromosomes showed a small marker chromosome in 3 of the 17 colonies analysed. Subsequently, C-banding showed no alphoid sequences, suggesting the presence of a neocentromere. The parent's karyotypes were normal. After normal ultrasound findings, the parents decided to continue the pregnancy. Chromosome analysis in peripheral blood after birth demonstrated that the marker chromosome was present in 50% of the lymphocytes. Using microFISH, the marker was further characterised and appeared to be derived from chromosome region (8)(p22 --> pter).
  
  
  CONCLUSIONS
  Accurate identification of the marker chromosome was very important for prenatal counselling. Combining the results of GTG- and C-banding analysis with the results of the (micro)FISH, we concluded that the patient's karyotype is: mos 47,XX,+mar.rev ish der(8)(p22 --> pter)[50]/46,XX[50].
authors.affiliation: Department of Biomedical Genetics, University Medical Centre, Utrecht, The Netherlands.
authors.forename: J M
authors.initials: JM
authors.lastname: de Pater
authors.forename: H Y
authors.initials: HY
authors.lastname: Kroes
authors.forename: M
authors.initials: M
authors.lastname: Verschuren
authors.forename: A C C
authors.initials: AC
authors.lastname: van Oppen
authors.forename: J C M
authors.initials: JC
authors.lastname: Albrechts
authors.forename: J J M
authors.initials: JJ
authors.lastname: Engelen
mesh_terms: D000328:Adult; D002898:Chromosomes, Human, Pair 8; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007231:Infant, Newborn; D008423:Maternal Age; D010375:Pedigree; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis; D014314:Trisomy / Q000175:diagnosis*