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Achondroplasia
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Achondroplasia is the most common form of skeletal dysplasia, meaning abnormal growth of the skeleton, and the most common genetic cause of dwarfism, with severe, disproportionate short stature: some parts of the body end up shorter than others.
It all starts in a gene. A point mutation, a change in a single letter of DNA, affects fibroblast growth factor receptor 3, a piece of the cell surface that receives growth signals. That gene sits on chromosome 4.
Bone has two ways of forming. One is endochondral ossification, which means first making cartilage and then turning it into bone; this is the one that lengthens the long bones. The other is intramembranous ossification, which forms bone directly and builds the flat bones, such as those of the face and the skull except its base. In achondroplasia the first one slows down and the second is generally spared. The body's blueprint is the same; only the stretch of bone that grows from cartilage got shorter.
In brief
Achondroplasia is the most common skeletal dysplasia and the most common genetic cause of dwarfism, with severe, disproportionate short stature.
It arises from a point mutation in fibroblast growth factor receptor 3, on chromosome 4.
That mutation slows endochondral ossification and the lengthwise growth of bone, while intramembranous ossification of the flat bones is generally spared.
The body's blueprint is the same; only the stretch of bone that grows from cartilage got shorter.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingAchondroplasia, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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