Satellited 4q identified in amniotic fluid cells.
Extra material was identified on the distal long arm of a chromosome 4 in an amniotic fluid specimen sampled at 16.6 weeks of gestational age. There was no visible loss of material from chromosome 4, and no evidence for a balanced rearrangement. The primary counseling issue in this case was advanced maternal age. Ultrasound findings were normal, and family history was unremarkable. The identical 4qs chromosome was observed in cells from a paternal peripheral blood specimen and appeared to be an unbalanced rearrangement. This extra material was NOR positive in lymphocytes from the father, but was negative in the fetal amniocytes. Father's relatives were studied to verify the familial origin of this anomaly. In situ hybridization with both exon and intron sequences of ribosomal DNA demonstrated that ribosomal DNA is present at the terminus of the 4qs chromosome in the fetus, father, and paternal grandmother. This satellited 4q might have been derived from a translocation event that resulted in very little or no loss from the 4q and no specific phenotype. This derivative chromosome 4 has been inherited through at least 3 generations of phenotypically normal individuals.
Miller
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Molecular and Clinical Cytogenetics Laboratory, Stanford University Medical Center, California, USA.
Songster
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Fontana
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Hsieh
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CL
D000653:Amniotic Fluid / Q000166:cytology*; D002894:Chromosomes, Human, Pair 4; D004276:DNA, Satellite; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male
D004276:DNA, Satellite