Achondroplasia | Genetic disorder | Bone Growth Disorder

 

Achondroplasia is generally described as a bone development disorder which results in dwarfism because of genetic or gene mutation in the arms and legs of your body. Achondroplasia comes under the form of short stature which means adults less than 4-ft. 10-in. in height. But almost all children who are affected with achondroplasia are able to live full and healthy lives after the diagnosis of disease.

In the early stages of fetal development, most of the fetal skeleton is mainly made up of cartilage tissue, which eventually turns into bone. Achondroplasia happens when the cartilage tissues do not develop complete bone development of your arms and legs. This genetic disorder leads to short-limb dwarfism with the upper parts of arms and legs being shorter than the lower portions of those limbs which means rhizomelic shortening.

Causes

Generally, achondroplasia disorder is typically caused by a mutated gene which is in the receiver that converts cartilage tissues to bone development during fetal growth. In the early stages of fetal development, most of the fetal skeleton is mainly made up of cartilage tissues. Typically these cartilage tissues develop into bone. But in some conditions, if you have achondroplasia, a large amount of cartilage tissue does not develop into bone. This is because of mutations in the FGFR3 gene.

Usually, this FGFR3 gene instructs your body to produce a protein necessary for bone growth development and its maintenance. Mutated FGFR3 gene usually causes the protein to be overactive. This typically interferes with normal skeleton development.

Symptoms

• Bones are shortened, especially thigh, upper arm parts

• Short hands and feet

• Large distance between third and fourth fingers

• Maximum height of 4 feet

• Head larger than usual

• Prominent forehead

• Flat nose

• Delayed development in infants for sitting, crawling, and walking

Children and adults with achondroplasia may:

• have difficulty bending in their elbows

• be obese

• experience recurrent ear infections because of narrow passages in the ears

• develop bowed legs

• kyphosis or lordosis which means develop an abnormal or unusual curvature of the spine

• It creates new or more severe form of spinal stenosis

Long-term effects 

• Back and leg pain.

• Apnea which means Breathing problems

• Obesity.

• Recurring ear infections.

• Curved spine.

• Bowed legs.

• Hydrocephalus which means excess fluid in your brain.

• Obstructive sleep apnea.

Diagnosis

Healthcare providers use ultrasound which helps to detect achondroplasia before you give birth if your baby’s arms and legs appear shorter than usual and average and if your baby’s head is large. In most cases, achondroplasia is not confirmed until the baby's birth.

• X-ray.

• Physical examination.

• If one or both parents are affected, it is necessary to do an parental examination.

• Genetic testing which helps to test the FGFR3 gene.

• MRI or CT scan which helps to identify muscle weakness or spinal cord compression.

Treatment

There is no specific treatment for achondroplasia, but healthcare providers and scientists were working on medicines which help with bone growth. Gene therapies are under study.

A group of specialists who cares for people with achondroplasia which includes:

• an orthopedic surgeon: who specialized in bone problems

• a genetics doctor: they help families to understand the genetic changes and they  recommend future health care

• a pulmonologist: who treats sleep apnea

• an otolaryngologist (ENT doctor): who treats ear fluid and/or infections

• a neurosurgeon: who treats for brain and spinal cord problems

• a pediatrician: for routine baby check ups

• an occupational therapist: who help with writing, eating, and other daily activities

Treatments may include:

• Changes in daily living activities like lower chairs with feet support, light switch extenders and stools for someone who needs

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• ear tubes to drain fluid from the ears

• After 2 years of age, weight management necessary

• Give back support for babies who affected with thoracolumbar kyphosis

• Treatment for sleep apnea

• surgeries to straighten the legs, straighten the spine, or helps to ease the narrowing of the spinal canal

• In some cases, the care team will recommend avoiding activities which have a risk of neck injuries like contact sports, gymnastics, and trampolines.

Manage the symptoms of achondroplasia

Managing achondroplasia is mainly focused on taking care of severe complications which includes:

• To prevent obesity, follow weight management and encourage healthy eating habits to prevent obesity.

• Surgery -  particularly ventriculoperitoneal shunt is used helps to decrease fluid pressure on your brain or  it helps to correct a severe life risking complication known as craniocervical junction compression.

• Surgery which removes adenoids and tonsils.

• Growth hormones

• Use of CPAP - continuous positive airway pressure for nasal mask for apnea.

• Ear tubes or antibiotics which help to prevent ear infections.

• Provide support for socialization.

• More research is being done on medications which helps to increase height by a few inches.

Frequently Asked Questions

Q1. What causes achondroplasia?

Ans: Achondroplasia is caused by a change (mutation) in the fibroblast growth factor receptor 3 (FGFR3) gene. 

Q2. How is achondroplasia diagnosed?

Ans: Achondroplasia can be diagnosed before birth by fetal ultrasound or after birth by complete medical history and physical examination. 

Q3. Is achondroplasia painful?

Ans: Bowing of the lower legs can cause pain and trouble with walking in children who have achondroplasia. 

Q4. Is achondroplasia present at birth?

Ans: Achondroplasia is a birth defect that affects a baby's bone growth. 

Q5. At what age is dwarfism diagnosed?

Ans: Disproportionate dwarfism is usually apparent at birth or early in infancy.