Malformation syndrome associated with small extra chromosome.

We report an infant with a previously apparently unreported lethal malformation syndrome concentrated primarily on the left half of the body, but including midline defects such as meningomyelocele, cleft lip and cleft palate, and imperforate anus. The infant also had a small extra metacentric chromosome in 60% of lymphocytes. It is postulated that the small extra chromosome (whose origin remains unknown) caused the infant's condition, and that its asymmetry is compatible with an uneven distribution of the normal and aneuploid cell lines in the two halves of the body during critical phases of prenatal development.