Tetraploidy: a report of three live-born infants.

We present three live-born infants with tetraploidy and compare them with two previously reported live-born infants with the same genetic defect. Common anomalies noted included microcephaly; a prominent, narrow forehead; microphthalmia/anophthalmia; cleft palate; orthopedic anomalies; genital ambiguity; and abnormalities of the central nervous system, including pituitary hypoplasia. Together these constitute a rather characteristic phenotype. An error in cytoplasmic cleavage is theorized to be a mechanism for the chromosome anomaly and is supported by the presence of parental polymorphisms in one of our cases; however, the presence of a small percentage of tetraploid cells in the leukocytes and skin fibroblasts of this patient's mother does not exclude maternal mosaicism as the basis for polyploidy in certain instances.