Achondroplasia is a genetic disease of the bone dysplasia type characterized by the presence of dwarfism. There is no cure but there is treatment that is aimed at alleviating the difficulties of those who suffer from it.
When there is already one of both parents affected by achondroplasia, Achondroplasia is a disease characterized by the presence of dwarfism or short stature associated with a series of added malformations as a result of an interruption in the development of the cartilage of the epiphyses (extreme ) Of bones. It mainly affects the long, faster-growing bones, such as the femur (in the thigh) and the humerus (in the arm).
The IQ of these patients is normal , even higher than the population mean. Therefore, schooling can be carried out in standard centers and a school with a special characteristic is not necessary.
Causes of achondroplasia
Achondroplasia is the most common non-fatal cause of chondrodysplasia . It appears in all human races and affects both sexes equally. The cause of the appearance of these mutations is not entirely well established.
- Due to mutations in the FGFR3 gene located on the short arm of chromosome 4. In most cases (greater than 95%) the parents are healthy (they do not have the disease) and spontaneous mutations appear in the child on said chromosome. that give rise to the expression of the disease.
- Because the genetic inheritance probability that the child suffers it is 50%. If both parents are affected, then the probability is 75% of the total.
Inheritance is autosomal dominant , that is, with the only involvement of one of the two chromosomes 4 that we have in all our cells (one from our father and one from our mother), the disease is already suffered. The homozygous form (both chromosomes 4 affected) is lethal.
Symptoms in addition to dwarfism
The phenotype (physical appearance) is very characteristic. These people present:
- Short stature or dwarfism . At birth, the newborn’s height is within normal standards, but final height will be affected.
- Short limbs, especially the femur and humerus. In the upper limb the forearm is longer than the arm. In addition, they are unable to fully extend the elbow joint, always remaining in half flexion. In the lower extremities there is usually the ‘ genu varus’ , or bowed legs and ligamentous laxity in the knees. The feet are small, flat and wide).
- Smaller hands , with a characteristic separation between the fingers causing the so-called “ trident hand ”. Long and narrow trunk (of normal length).
- Dorsal kyphosis (hump in the mid-vertebral area)
- Lumbar hyperlordosis (abnormal curve, forward, in the lower part of the spine) and, sometimes, stenosis – narrowing – of the vertebral medullary canal, which compresses the spinal cord.
- Macrocephaly (head of increased diameter) with brachycephaly (wide and short skull), prominent forehead, midface hypoplasia (small face) and nose with a characteristic “saddle” shape (flat back of the nose).
- Dental malocclusion.
How is it diagnosed?
Prenatal diagnosis using 3D and 4D ultrasound allows for greater accuracy in diagnosing skeletal bone dysplasias, in which the length of the femur is routinely measured in relation to the fetal cranial biparietal diameter. Also, the bone X-ray is useful to confirm the diagnosis.
The confirmation of the condition of the disease is carried out by means of the genetic study of cellular samples obtained by amniocentesis or chorion biopsy .
Do you have treatment?
There are currently no curative treatments for this disease. However, it should be noted that surgical treatment of bone lengthening at the limb level has been used in some cases, obtaining mixed results.
Treatment is aimed at alleviating difficulties . Medical care must be multidisciplinary, made up of various specialists in different fields:
- Occupational therapy
- Social care
In addition, it is a comprehensive treatment that is offered to both the patient and their families)
What you should know…
- Androplasia is a disease characterized by the presence of dwarfism associated with a series of additional malformations.
- In most cases the parents are healthy and spontaneous mutations in a chromosome appear in the child.
- There is no curative treatment, but rather aimed at alleviating difficulties.