Scientists at Cold Spring Harbor Laboratory (CSHL) solved the mystery of why some infants are born with cleft palate and major deformities of the skin and limbs, while other infants with the same genetic mutation bear little or no sign of the illness, called Ectodactyly, Ectodermal dysplasia, Clefting syndrome, or EEC. EEC is autosomal dominant, meaning that only one parent needs to contribute the defective copy of the gene for a child to develop the illness. When one parent carries the mutant gene, each child has a 50 percent chance of having EEC. The recent experiments reveal that the presence or absence of one variant type of the p63 protein, called TAp63, determines whether or not a child with the p63 mutation will in fact develop EEC pathology. TAp63 normally protects from the birth defects, and if it is not present, pathology is certain to occur, the team's experiments showed. This work suggests that levels of the TAp63 protein determine whether children that have inherited one copy of the EEC-causing mutation from one of their parents are born with birth defects. The authors speculate that when levels of TAp63 drop beneath a certain threshold, it is no longer protective, opening the way to pathology. “An Allelic Series of Trp63 Mutations Defines TAp63 as a Modifier of EEC Syndrome” was published in the American Journal of Medical Genetics by Emma Vernersson Lindahl, Elvin L. Garcia, and Alea A. Mills.