Achondroplasia is a type of dwarfism characterized by small limbs. The word means “lack of cartilage formation.” Cartilage is a tough but flexible tissue that accounts for a large portion of the skeleton during early growth stages. The issue with achondroplasia, however, is not the poor development of this connective tissue but rather the ossification of it into bone, particularly in the arms and legs. This genetic disorder is similar to hypochondroplasia, but the symptoms are more severe.

Causes
During the early fetal stage, cartilage forms the majority of the skeleton. A large portion of this tissue ultimately converts to the bone. However, in achondroplasia, a significant portion of the cartilage does not get transformed. Mutations in the FGFR3 gene cause this disorder.

This gene encodes a protein that is involved in the growth and maintenance of bone and brain tissue. Almost all instances of achondroplasia are caused by two specific mutations in the FGFR3 gene. Researchers think that these changes cause the FGFR3 protein to become overly active, interfering with skeletal development and resulting in bone growth problems seen in this disorder.

Inheritance
One altered gene copy in each cell is sufficient to produce achondroplasia because it is inherited in an autosomal dominant manner. About 80% of individuals with this genetic disorder are born to average-sized parents. The remaining instances of achondroplasia have one or both parents with the disordered FGFR3 gene. A severe form of the disorder with extreme bone shortening and an underdeveloped rib cage comes from the normal inheritance of two altered copies of this gene. Usually, these babies are stillborn or pass away due to respiratory failure soon after delivery.

Symptoms
A child with this condition is prone to have the following features at birth:

• A short stature that is considerably shorter than average for the age and gender
• Short legs and arms relative to body height, particularly the upper arms and thighs
• Short fingers, with the ring and middle fingers pointing away from each other
• An abnormally large, prominent forehead
• A region of the face between the top jaw and forehead that is underdeveloped

Symptoms in adults include:

• Back and limb aches
• Breathing difficulties (apnea)
• Recurring ear diseases
• The vertebrae get curved
• Brain fluid accumulation (hydrocephalus)
• Obstructive sleep apnea

Diagnosis
Ultrasound scans can identify achondroplasia before birth, but a majority of the cases are not discovered until after delivery. A genetic examination may be performed if your doctor suspects this disorder in the fetus. This test can detect any alteration in the FGFR3 gene, if present. For this, cells are collected from the amniotic fluid.

After birth, the doctor can diagnose a child based on his or her appearance. X-ray examination may also be suggested by the doctor to determine the length of your infant’s bones. This can aid in the prognosis. Blood tests to check for any mutation in the FGFR3 gene may also be recommended.

Treatment options
Aside from symptom management, there is no treatment for achondroplasia.

Spinal fusion
Some people with achondroplasia acquire spinal curvature. Not every instance of spinal deformation causes symptoms, and not every case requires treatment. Spinal fusion is a surgical procedure that includes joining together several vertebrae in the spine. The treatment aids in the reduction of excessive curvature and may help in the stabilization of the spine.

There are two primary reasons why someone with achondroplasia may need spinal fusion:

• Treating lumbar spinal stenosis (LSS)
• Achondroplasia patients may experience lumbar spinal stenosis (LSS), a narrowing of the canal through which the spinal nerve travels. This is the most frequent reason for the impairment seen in achondroplasia cases.
• Treatment for thoracolumbar kyphosis (TLK)
• There is a greater possibility that achondroplasia patients have TLK, an upper spinal curvature. Only in severe cases of TLK, where braces and other therapeutic measures have failed, do doctors usually recommend spinal fusion.

Guided growth and osteotomy
Leg bowing is a frequent achondroplasia symptom. There are two primary surgeries for treating bowed legs:

• Guided growth procedure (GGP)
• This technique is only appropriate for growing children. In the GGP procedure, one-half of a deformed bone is attached to a special growth plate. The tethered side grows slower than the untethered side, enabling the bone to straighten gradually.
• Osteotomy
• This procedure includes cutting the tibia and fibula in the lower legs and realigning them with pins, plates, and screws or an external frame that is attached to the bones. There is compelling evidence that osteotomy can assist individuals with achondroplasia in reducing leg bowing.

Helpful tips
Children with achondroplasia can enjoy normal, active lives. After attending to your child’s health requirements, concentrate on creating a welcoming environment where your kid can thrive. This can be done by:

• Removing physical obstacles to encourage independence (use of a step stool, extending light switches)
• Providing emotional support
• Supporting academic and non-academic activities
• Engaging with dwarfism-related clubs and organizations