Achondroplasia

Name: Craig Elice Date: October 3, 2008

Achondroplasia is an autosomal dominant that is a common cause of inherited dwarfism with disproportionate short stature with a normal sized torso and distal appendages. Its prevalence is 1 in 25000 births. Molecular analysis reveals a deficiciency in the fibroblast growth factor receptor. In 99% of the cases it is due to a mutation in the FGFR3 gene which indicates that there is a low risk of having another child with achondroplasia. There is an association with increased paternal age.

Diagnosis is made with a prenatal ultrasound. Infants generally have low muscle tone and slow motor development like sitting up and walking. Because of the narrow middle ear canals, these patients are susceptible to ear infections. A skeletal survey shows a large skull, with a small skull base, short ribs and a narrowing of the interpediculate distance between caudal vertebrate. A notch like sacroiliac groove is also indicative of achondroplasia. These patients have abnormal bone growth resulting in short stature and disproportionately short arms and legs. Average height is approximately 131 cm for males and 124 cm for females. They also have frontal bossing and midfacial hypoplasia.

These patients are often obese at a young age and develop sleep apnea. Adults frequently have symptomatic spinal stenosis of the lumbar vertebrae at L1-4 requiring pain medication and sometimes surgical intervention.

In terms of dental manifestations, the facial structures are listed above with midfacial hypoplasia. As a result, the patients frequently have severe crowding requiring orthodontic intervention.