Hello and welcome to the Zero to Finals podcast. My name is Tom, and in this episode,

I'm going to be talking to you about acondroplasia. And you can find written notes on this topic

at zero definals.com slash acondroplasia or in the orthopedic section of the Zero Definals

Pediatrics book. So let's get straight into it.

Acondroplasia is the most common cause of disproportionate short stature,

which is sometimes referred to as dwarfism.

It's a type of skeletal dysplasia.

Let's start by talking about the genetics of acondroplasia. The acondroplasia gene,

which is fibroblast growth factor receptor 3, FGFR3, is on chromosome 4. Aconraplasia results from

either a sporadic mutation in this gene or inheritance of an abnormal

copy of the gene. The condition is inherited in an autosomal dominant pattern. Being homozygous

for the gene mutation, meaning that you have two abnormal gene copies of the acondroplasia gene is fatal in the neonatal period.

Therefore, patients with acondroplasia have one normal gene and one abnormal gene.

Mutations in the fibroblast growth factor receptor 3 gene cause abnormal function of the epiphyseal

plates or the growth plates.

This restricts the bone growth in length leading to short bones and short stature.

So let's talk more about the features.

Patients with acondroplasia have disproportionate short stature.

The average height is around four feet. The limbs are

most affected by the reduced bone length. The femur and the humerus in the proximal limbs

are affected more than the bones of the forearm and the lower leg in the distal limbs. The spine

length is less affected and patients have a normal trunk length.

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