13S+. Giant satellites or de novo rearrangement?

A seven-year-old Japanese girl with mental retardation, epileptic seizures controllable by anticonvulsants, short stature, and multiple minor malformations was found to have apparent giant satellites on chromosome No.13. The karyotypes of her parents and elder brother were normal. Banding studies revealed that the apparent giant satellites consist of four G-bands, and are thus a de novo rearrangement product. The origin of the aberrant No. 13 was traced to a paternal meiotic error, using Q-banding and silver staining heteromorphisms as markers. Thus, the patient represents an unbalanced, de novo chromosomal rearrangement masquerading as giant satellites, with the origin of the extra chromosomal material unknown, a hitherto undescribed situation.