Achondroplasia is a bone growth disorder characterized by dwarfism and disproportionate body. Patients with achondroplasia have normal chest size, but the size of the arms and legs short. The average height of patients with adult male achondroplasia is 131 cm, while for adult women is 124 cm. Despite his abnormal physical condition, achondroplasia sufferers have normal levels of intelligence.
Causes of Achondroplasia
The cause of achondroplasia is a genetic mutation. Genetic mutation is a permanent change that occurs in the DNA sequence that makes up the genes. In patients with achondroplasia, mutations occur 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, namely the process of cartilage changes into hard bones. Mutations in the FGFR3 gene cause proteins not to function normally, thus disrupting cartilage changes to bone. This condition causes the bones to grow shorter and has abnormal shape, especially bone in the arms and legs.
There are two causes of FGFR3 gene mutation in patients with achondroplasia, namely:
- Mutations that occur spontaneously. Approximately 80% of achondroplasia is caused by a mutation of genes that are not inherited from their parents. Mutations occur spontaneously, but the trigger is unknown.
- Inherited mutations. Approximately 20% of cases of achondroplasia are inherited from the elderly. If one parent has an achondroplasia condition, then the percentage of children suffering from achondroplasia is 50%. If both parents have an achondroplasia condition, then the possible risks are as follows:
- 25% chance of normal body.
- 50% chance of having one defective gene, causing achondroplasia.
- 25% chance of inheriting two defective genes, thus causing fatal achondroplasia.
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Physical Characteristics of Achondroplasia
Since birth, babies with achondroplasia can be identified by their physical characteristics, including:
- The size of the arms, legs and fingers are short.
- The size of the head is larger, with a prominent forehead.
- Teeth that are not parallel and attached.
- There is a space between the middle finger and the ring finger.
- Having a spinal deformity, can be in the form of lordosis (curved forward) and kyphosis (curved to the back).
- The spinal canal is narrow.
- O-shaped limbs
- The soles of the feet are short and wide.
- Tonus or weak muscle strength.
- Recurrent ear infections , due to narrowing of the canal to the ear.
- Limitations in moving, due to decreased muscle tone.
- Spinal stenosis, the narrowing of the spinal canal that results in the depression of the nerves in the spinal cord.
- Hydrocephalus, the accumulation of fluid in the cavity (ventricle) in the brain.
- Sleep apnea, a condition characterized by the cessation of breathing during sleep.
Diagnosis of Achondroplasia
As a first step, your doctor may conduct a medical history of the patient and the patient's family, as well as the overall physical examination. Patients with achondroplasia can be seen from birth with short and disproportionate limb trait. To determine the diagnosis of achondroplasia can also be done during pregnancy, especially for elderly people who suffer from achondroplasia. Some investigations that can be done to detect achondroplasia, among others:
- During pregnancy.
- USG. To check the condition of the fetus in the uterus and to detect any sign of achondroplasia, such as hydrocephalus. Ultrasound can be done through the abdominal wall of the mother (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 taking samples of amniotic fluid ( amniocentesis ) or placental or placental tissue samples, called chorionic villus sampling . However, this action risks miscarriage.
- After the baby is born.
- DNA testing The DNA test was performed to confirm the diagnosis of achondroplasia. DNA testing is done by taking DNA samples from the blood to be analyzed in the laboratory. The DNA samples were used to detect possible abnormalities in the FGFR3 gene.
Treatment of Achondroplasia
Until now, there is no cure or any treatment method that can treat achondroplasia. Treatment is only intended to treat complications that arise, such as:
- Antibotics. To treat ear infections that may suffer sufferers achondroplasia.
- Anti- inflammatory drugs . To treat achondroplasia patients with joint disorders.
- Operation. Surgery can be done to overcome the possible complications, including:
- Orthopedic procedures. The procedure performed by orthopedic doctors to improve the shape of the foot O.
- Lumbar laminectomy. Operating procedure for dealing with spinal stenosis .
- Ventriculoperitoneal shunt. The surgical procedure performed if the achondroplasia suffers from hydrocephalus . This procedure is performed by inserting a flexible tube (catheter) to drain the fluid inside the brain cavity into the abdominal cavity.
- Caesarean section. Childbirth procedures are generally passed by women suffering from achondroplasia because it has a small pelvic bone. Cesarean section is also performed if the fetus is diagnosed with achondroplasia. This is done to reduce the risk of bleeding due to the fetal head is too large to be born normally.
Prevention of Achondroplasia
Precautions against achondroplasia are not known until now. If you are a sufferer or have a family history of achondroplasia, then you can consult a geneticist to find out more about the risk of achondroplasia in the child to be born. Patients with achondroplasia can also take preventive measures by avoiding dangerous activities that are at risk of spinal damage.