It’s known as dwarfism more commonly.  But technically, it’s called achondroplasia.  Dwarfism appears in one out of every 25,000 births, and it spreads itself equally across races and sexes in general.  Dwarfism has been seen and recorded as far back as Ancient Egypt.  It is genetic, so it can be passed on through generations in general, but it’s usually not.  Average sized parents can have children with dwarfism as dwarves can have children of normal stature.  Achondroplasia is a mutation in the egg or sperm cell in the embryo.  It is unusual for parents to have more than 1 child with it, but it is more likely for a dwarf to pass on this gene to their own children, especially if they are with another dwarf.  If a child inherits this gene from both parents however, it actually becomes fatal.  It is a failure of the cartilage of the bone to form correctly and makes limbs shorter.  Now there have been some who have driven metal screws into joints damaging them and letting them heal, making limbs longer over time.  But this cannot combat a susceptibility to breathing problems among other things like water in the brain.  Many have to wear a shunt all their lives.  Some are suggesting that they may also be deficient in HGH and therefore are supplementing it in to at least induce greater growth.  This is a popular alternative to the other painful surgery.  But they still need to do more research.