What is Skeletal Dysplasia?
Skeletal dysplasia literally means “bad skeletal growth”. The condition is also known as dwarfism or in layman’s terms; little people or short stature. A person is suffering from skeletal dysplasia when your height is below the 2.5th percentile of what your mean age group and sex normally have. A height drop of 2 or more percentiles stipulated from the growth chart indicates growth deceleration, which is the main presentation of the disease.
According to epidemiological reports, about 2% of all children in the United States have short stature. However, it doesn’t implicate that they are suffering from skeletal dysplasia because among all the reported children with short stature in the US have no organic cause or is pointed out to be related to growth delays and familial inheritance. In addition, skeletal dysplasia can be diagnosed early while others during their childhood. However, the condition is found related to a specific gender which is the male population. Study shows that men are mostly affected because most types of skeletal dysplasia are due to X-linked recessive inheritance.
Picture : Skeletal Dysplasia
Skeletal Dysplasia in Fetus
Skeletal dysplasia in fetus can be diagnosed through a sonogram examination. With this disease, fetal development is greatly affected resulting to bone and cartilage problems. It is observed that the fetus is suffering from abnormal limb growths, absence of some limb/s, and other forms of deformities. There are cases where skeletal dysplasia is not diagnosed before birth as statistics shows only 65% of all cases were precisely diagnosed prenatally.
It’s therefore essential that pregnant women attend their routine prenatal checkups. When skeletal dysplasia suspected, the obstetrician shall perform a more sophisticated form of ultrasound examination which is the 3D ultrasound. This can help view presence of abnormal limb lengths and missing bones. When these are identified through the 3D ultrasound, another test will be performed. Fetal MRI will aid in identifying which type of dysplasia the fetus is suffering from. Genetic testing is also performed to confirm the diagnosis of fetal skeletal dysplasia.
The abnormalities noted are the following:
- Short arms and trunk
- Skull malformation (large head)
- Anomalies found on the hands and feet such as development of extra fingers
Skeletal Dysplasia Causes
The following are the said causes of skeletal dysplasia:
- Genetic profile. The condition is related to a genetic mutation. With the child’s genetic profile, we can easily find out the cause and type of disorder the child is suffering from (discussed below).
- Familial short stature. Some cases of skeletal dysplasia are identified after birth, some during infancy while others during their childhood age. But it becomes prominent when there is a significant decrease in the growth velocity of the child between 6 to 18 months of life.
- Pregnancy complications. The condition is said to be related with the mothers’ history of pregnancy. When the mother suffered from maternal hydramnios, the unborn child becomes at risk for skeletal dysplasia.
Skeletal Dysplasia Types
The following are considered the most common types of the disease:
- Achondroplasia. This is reported as the most common type and form of skeletal dysplasia. The said type is basically caused by a mutated gene and is inherited through an autosomal dominant manner. The person affected of this condition has an average height of 131 centimeters or 4.3 feet. The abnormality arises when changes of the DNA fibroblast growth factor receptor 3 (FGFR3) has occurred.
- Pseudoachondroplasia. The condition was associated with achondroplasia back then. Now, pseudoachondroplasia has become a separate disorder because of its different cause. There are mutations of the COMP gene that results to short limbs, waddling gait, and osteoarthritis. Basically, the cartilage is the main affectation of the disorder by initiating early death of the cartilage-forming cells (chondrocytes).
- Spondyloepiphyseal dysplasia. The condition is conveniently identified as SED which is a rare cause of dwarfism. The condition can be fatal as this also affects the child’s vision and hearing senses. It directly affects a child’s spine leading to a short stature and very short trunk and limbs. A genetic mutation from the COL2A1 gene is the main cause of the skeletal disease.
- Metaphyseal chondrodysplasia. This has 3 different types as different genetic mutations cause the problem. Mutations of the adenosine deaminase gene and procollagen X gene cause two of the three types of metaphyseal dysplasia. While a mutation of the gene responsible in the production of parathyroid hormone also results to metaphyseal chondrodysplasia.
Diagnosis For Skeletal Dysplasia
The condition is diagnosed through the following tests:
- Physical examination. This includes measuring the child’s growth, by sizing up the body and limbs proportion. It is ideal that monthly measurement is done to the child in the first year of life to properly monitor the disorder’s progression.
- Series of X-rays and CT scans. This can help identify skeletal underdevelopment or abnormalities.
- MRI. This is done when the child is more than six months of age. This shall include getting images of the child’s brain and spinal cord. This is done when a surgical intervention is planned.
- Chromosome analysis. This test is performed in order to identify the exact cause and type of skeletal dysplasia.
Management of Skeletal Dysplasia
Management for skeletal dysplasia shall include the following.
We need supportive care with skeletal dysplasia. When a newborn child is diagnosed with skeletal dysplasia, we need to assist their respiratory system. Newborns have a tendency to suffer from a respiratory distress because of skeletal dysplasia. Monitoring the child’s height, weight and head circumference is essential in order to assess the progress of the condition.
This depends on the severity of the condition. Most cases would indicate surgical intervention and assistive devices. When the child is suffering from thoracolumbar kyphosis, the use of a (1) Milwaukee brace is provided in order to avoid progression of the medical problem. (2) Surgical decompression is done to avoid spinal cord decompression or to find relief from it. This can also remove the developing spinal edema which is likely a cause of spinal cord decompression. When scoliosis becomes progressive and a source of pain and discomfort, (3) spinal fusion is performed.
Progress of the disease may lead to physical limitations which is why the child tends to become inactive and awkward. Presenting a wider variety of activities that does not place harm to the child should be done. We need to also support the child, especially as they grow, for they need that to feel socially accepted. Emotional support is very essential in the treatment process.