Achondroplasia is a disorder affecting the growth of bone and people with this disorder will have abnormally short stature with short limbs. It can cause some complications in the brain and spinal cord but people with achondroplasia will have normal intelligence. Gene mutation is the main cause of this disorder and it can be diagnosed well before birth. The average height of affected person will be below 4 feet or 120-130 cm.
The term “achondroplasia” means without cartilage but the defective person will have cartilages that cannot convert into bone. Hence this disorder is marked by short bone structure. On average, one out of every 20,000 children will have this disorder.
Causes :
Achondroplasia occurs due to gene mutation. The gene responsible for mutation is the FGFR3 gene that encodes with a protein of fibroblast growth factor receptor 3. It undergoes gene mutation forming new set of genes. This particular protein is vital for the maintenance of bone and tissues. Due to mutation there may not be sufficient growth of bone from the cartilages causing stunted growth with short structure.
Signs and Symptoms :
The child with achondroplasia can be diagnosed shortly after birth. The baby will have a long trunk marked with short arms and legs. The characteristic disproportion of shortening of extremities can be very well observed in the development of arms and thighs. The infant will have large head with marked forehead, an underdeveloped midface region, underdeveloped cheekbones and lower nasal bridge with narrow passage.
The fingers of the child will be very short and on close observation the middle fingers will be seen diverging thus giving triangle like appearance. Most of the joints will extend beyond normal level. Knee joints will often extend further in children affected with achondroplasia. However the elbow joints are limited in size.