Chromosomal abnormalities in the newborn period.

Chromosomal abnormalities account for a significant percentage of congenital malformations in the neonate. While some of the syndromes can be suspected on clinical grounds, the clinician will need to have a high index of suspicion based on the presence of multiple abnormalities that cannot be accounted for by other causes. Chromosome analysis should be performed promptly in these cases. Cultured lymphocytes are the standard preparation at present. However, new non-isotopic hybridization techniques are becoming available that allow analysis of interphase cells, and these may become more widely used as clinical experience with them is gained. Prognosis can usually be better defined once the chromosome analysis is complete. The information acquired may also be used to provide risk estimates for chromosomal abnormalities in future pregnancies of the parents of the affected infant and for other relatives. Empathetic counseling of the parents and family must be provided once the diagnosis is known. It must take into account the knowledge the chromosome analysis provides, be respectful of the parent's need for support, and be accurate as to prognosis of the condition diagnosed. When Down syndrome and Turner syndrome have been diagnosed, care must be taken to emphasize the positive aspects of the prognosis. When a chromosomal abnormality with an extremely poor prognosis is identified, support for withdrawal of medical intervention must be sensitively provided. The diagnosis and care of an infant with a chromosomal abnormality will challenge all of the pediatrician's diagnostic, therapeutic, and communication skills.