Cytogenetic studies of normal and cleft-palate epitheliums in mice.

Cleft of the primary and secondary palate in human beings is a frequent congenital malformation occurring once in 800 live births.' In Michigan, this congenital defect is incident once in 740 live births.2 Although both genetic and environmental forces are involved in cleft formation, the genetic mechanism has not been described adequately or have specific environmental agents been identified. Research continues to seek the pathogenesis and the etiologic factors for cleft deformity. The report of Gropp, Jussen, and Odunjo3 of a near-triploid epithelial cell culture derived from the palatal mucosa of a child with cleft palate and lip aroused great interest in the possibility that other persons with cleft palate would have abnormal chromosomal patterns. Reports on the karyotypic findings in human cleft-palate tissues have been conflicting. Soukup and Warkany4 reported cytogenetic studies in cultures of palatal tissues from six patients with cleft palate, of which all but one also had cleft lip. These investigators found no chromosome abnormalities in their group of children. Similarly, Jackson5 reported a modal number of 46, with karyotype analyses of modal cells consistent with the phenotypic sex in each of eight instances of cleft-palate tissue cultures. On the other hand, Murphy and Reisman,6 in cultured