Incidence and significance of supernumerary marker chromosomes in prenatal diagnosis.

摘要: Abstract The finding of a supernumerary marker chromosome in amniotic fluid cells poses considerable counseling dilemma. In 6,500 cases referred to our laboratory over 4 1/2-year period, eight such were identified (0.123% all cases). five the cases, diagnosis true mosaicism between with 46 and 47 chromosomes was made. remaining three present 100% cells. determined be familial nature parents two these cases. Detailed cytogenetic findings for each case are provided. no abnormalities noted either abortuses or live borns. The high incidence seems indicate propensity lost. Familial markers may not passed on many generations, they arise as new mutations relatively frequently. There is an urgent need more information risks associated prenatal detection chromosomes. We recommend that considering implications considered at least four distinct groups: type 1--familial nonmosaic; 2--familial cells, parent, both; 3--de novo 4--de