Achondroplasia is a bone growth disorder characterized by a stunted body and disproportionately large limbs. This condition is one of the most common types of bone growth disorders.
Achondroplasia is characterized by the size of the arms and legs are short, causing the sufferer to have a stunted body ( dwarfism ). Achondroplasia is a rare disorder that only occurs in 1 in 15,000–40,000 births in the world.
The average height of adult patients with achondroplasia is 131 cm in men and 124 cm in women. Despite having different physical conditions, achondroplasia sufferers have a normal level of intelligence like normal people in general.
Causes of Achondroplasia
Achondroplasia is caused by a genetic mutation in the FGFR3 gene, the gene that produces the Fibroblast Growth Factor Receptor 3 protein. This protein plays an important role in the ossification process or the process of changing cartilage into hard bone.
The mutation of the FGFR3 gene causes the protein to not function properly so that it interferes with the transformation of cartilage into hard bone. As a result, the bones grow shorter with an abnormal shape, especially the bones in the arms and legs.
FGFR3 gene mutations in patients with achondroplasia can occur in two ways, namely:
Most cases of achondroplasia are caused by gene mutations that are not inherited from parents. This mutation occurs spontaneously and the cause is unknown.
About 20% of cases of achondroplasia are inherited from parents. If one parent has achondroplasia, the percentage of children suffering from the condition can be as high as 50%. However, if both parents suffer from achondroplasia, the risk for the child to also suffer from this condition is as follows:
- 25% chance that the child will be normal
- 50% chance the child has one defective gene that causes achondroplasia
- 25% chance the child will inherit two defective genes causing fatal achondroplasia ( homozygous achondroplasia a )
Symptoms of Achondroplasia
From birth, babies with achondroplasia can be recognized by their physical characteristics, such as:
- Short stature that is far below the average height of a child his age
- Short arms, legs and fingers
- Larger head size, with a prominent forehead
- Teeth that are misaligned and attached
- Spinal deformities, can be in the form of lordosis (curving forward) or kyphosis (curving back)
- Narrow spine
- Legs form the letter O
- Feet short and wide
- Weak muscle strength
When to go to the doctor
If a member of your family has a history of achondroplasia, get a genetic test before planning a pregnancy. The goal is to find out how much risk this abnormality is passed on to the fetus.
If you or your child is diagnosed with achondroplasia, it is advisable to undergo regular check-ups with the doctor to prevent complications. It should be noted that the risk of achondroplasia complications can increase over time so that early treatment is expected to prevent worsening of symptoms.
Diagnosis of Achondroplasia
Achondroplasia can be diagnosed early in the womb or when the baby is born. Here is the full explanation:
After the baby is born
As a first step, the doctor will examine the patient's physical symptoms and conduct questions and answers with parents regarding family medical history. Achondroplasia can usually be recognized by the feature of disproportionately short limbs, which can be measured by a thorough physical examination.
To confirm the diagnosis, the doctor can also perform further tests with DNA tests. This test is done by taking a DNA sample from the blood for later research in the laboratory. The DNA sample is used to detect possible abnormalities in the FGFR3 gene.
The diagnosis of achondroplasia can also be made during pregnancy, especially for parents who suffer from achondroplasia. Some tests that can be done to detect achondroplasia are:
Ultrasound of the womb
Ultrasound of the womb is used to examine the condition of the fetus in the womb and detect signs of achondroplasia, such as a larger-than-normal head size. Ultrasound can be done through the mother's abdomen (transabdominal) or through the vagina ( transvaginal ultrasound ).
Detection of FGFR3 gene mutations
Detection of gene mutations while still in the womb can be done by examining samples of amniotic fluid (amniocentesis) or samples of placental tissue (uterine), which is called chorionic villus sampling . However, this action carries the risk of causing a miscarriage.
To date, there is no method to completely treat achondroplasia. Existing treatment is limited to relieving symptoms or preventing and treating complications that arise. These handling methods include:
1. Medical check-up
Routine medical check-ups aim to monitor the patient's body growth. This examination includes measuring the ratio of the upper to lower body. Doctors will also continue to monitor the patient's weight to prevent obesity.
2. Hormone therapy
In children with achondroplasia, doctors will recommend regular hormone therapy . The goal is to increase the growth of the child's bones so that he can have a better posture as an adult.
3. Dental care
Dental treatment aims to improve the structure of the stacked teeth experienced by achondroplasia sufferers.
Antibiotics can be used to treat ear infections that are often experienced by people with achondroplasia.
5. Anti-inflammatory drugs
Anti-inflammatory drugs can be given to treat patients with achondroplasia who also have joint disorders.
Surgery can be performed to relieve symptoms or treat complications that occur. Operations that can be performed include:
Orthopedics are performed by doctors to correct the O shape of the foot .
Lumbar laminectomy is performed to treat spinal stenosis .
This operation is performed if the patient has hydrocephalus . This procedure is done by inserting a flexible tube (catheter) to remove excess fluid in the brain cavity.
Pregnant women with achondroplasia have small pelvic bones so it is advisable to give birth by caesarean section . Caesarean section is also necessary if the fetus is diagnosed with achondroplasia, in order to reduce the risk of bleeding due to the fetal head being too large for normal delivery.
Tonsillectomy and adenoidectomy
Doctors may perform surgical removal of the tonsils (tonsillectomy) and removal of the adenoids (adenoidectomy). This is because people with achondroplasia can experience deformities of the middle facial bones so that they are at risk of causing swelling of the tonsils and adenoids.
Complications of Achondroplasia
There are various complications that can be experienced by patients with achondroplasia, including:
- Overweight and obesity
- Recurrent ear infections, due to narrowing of the ear canal
- Limitations in movement, due to deformities of the arms and legs
- Spinal stenosis , which is a narrowing of the spinal column that causes the nerves in the spinal cord to be compressed
- Hydrocephalus, which is a buildup of fluid in the cavities (ventricles) in the brain
- Sleep apnea , which is a condition where the rhythm of breathing stops during sleep
Prevention of Achondroplasia
Until now, not yet known with certainty how to prevent achondroplasia. However, if you suffer from achondroplasia or have a family history of achondroplasia, it is advisable to consult a doctor to find out more about the risk of passing achondroplasia to children.