Abstract
An estimate is derived of the mutation rate of achondroplasia, based upon recent newborn studies. In a total of 242,257 births, 7 infants had mutant achondroplasia, the diagnosis being confirmed radiologically in all but one. From this, the rate of mutation of the normal to the achondroplasia allele is calculated to be 1.4 .times. 10-5 .+-. SE 0.5 .times. 10-5. Certain shortcomings of this estimate are discussed.