Achondroplasia occurs from a mutation in the FGFR3 gene, which is responsible for the development and maintenance of bone and brain tissue. It occurs in one out of every 26,000 to 40,000 live births. It is an autosomal dominant trait. Autosomal meaning it occurs on one of the non- sex linked chromosomes and dominant meaning only one gene is needed to inherit the trait. Therefore a parent with Achondroplasia has a 50% chance of passing it down to their children. However 80% of Achondroplasia cases occur from a new mutation, where the parents do not carry the gene. In these cases the mutation occurs at conception.