Achondroplasia is the most common type of dwarfism, in which the child's arms and legs are short in proportion to body length. Further, the head is often large and the trunk is normal size.
Achondroplasia is inherited by an autosomal dominant gene that causes abnormal cartilage formation.
This means that males and females are equally affected. Dominant means that only one gene is necessary to have the trait. When a parent has a dominant trait, there is a 50 percent chance that any child they have will also inherit the trait. So, in some cases, the child inherits the achondroplasia from a parent with achondroplasia. As mentioned, persons with achondroplasia have a 50 percent chance to pass the gene to a child, resulting in the condition.