TISSUE-SPECIFIC MOSAICISM AMONG FETUSES WITH PRENATALLY DIAGNOSED DIAPHRAGMATIC-HERNIA

OBJECTIVE: Our purpose was to determine if cytogenetic discrepancies b etween fetal blood and amniotic fluid are present in fetuses with pren atally diagnosed diaphragmatic hernia STUDY DESIGN: Chromosome analysi s was performed on 15 fetuses with prenatally diagnosed diaphragmatic hernia. Fourteen had both amniotic fluid and fetal blood studies One f etus had an amniocentesis followed by postnatal skin and peripheral ly mphocyte chromosome analysis. RESULTS: In one fetus with a normal kary otype on fetal blood, amniotic fluid mosaicism for a supernumerary iso chromosome 12p was identified, Another fetus had normal amniotic fluid chromosome analysis but was diagnosed with mosaic isochromosome 12p o n skin biopsy after birth. Concordant aneuploidy in both fetal blood a nd amniocytes was found in five pregnancies (three with trisomy 18, on e with an unbalanced translocation, and one with mosaic supernumerary isochromosome 12p). Eight fetuses had normal karyotypes, CONCLUSION: B ecause diaphragmatic hernia is a common component of mosaic isochromos ome 12p syndrome and this chromosome abnormality is predominantly foun d in fibroblasts but not lymphocytes, an amniocentesis may be more acc urate than fetal blood sampling in defining the true fetal chromosome status when diaphragmatic hernia is detected prenatally.