1 Genetic and Endocrine Unit Department of Pediatrics State University of New York Upstate Medical Center Syracuse, New York
Follow-up observations are reported on an infant with numerous phenotypic abnormalities who had been reported at 7 months of age to have an extra C group autosome in 17% of her peripheral leucocytes. Examination of the patient at age 2
years revealed that the physical findings were essentially unchanged, except for increased prominence of the sixth, seventh, and eighth thoracic vertebrae. The abnormal cell line was found to have disappeared from her leucocytes in cultures repeated at ages 2
and 2[unknown] years. Analysis of bone marrow metaphases showed that 7% were of the 47,XX,C+ karyotype.
Other reported examples of disappearing abnormal cell lines are reviewed. These findings may help explain those cases having the clinical appearance of a syndrome associated with chromosomal abnormality, but whose karyotypes are normal. It is possible that a mosaicism existed during fetal life, and that the cytogenetically abnormal cell line caused abnormal organogenesis prior to its later disappearance.