What is Achondroplasia?

What is Achondroplasia?

Achondroplasia is a genetic disease of the bone dysplasia type that is 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.

Content Summary

  • Causes of achondroplasia
  • Symptoms besides dwarfism
  • How is it diagnosed?
  • Do you have treatment?

When one of both parents is already affected by achondroplasia, the Achondroplasia is a disease characterized by the presence of dwarfism or short stature associated with a series of additional malformations as a result of an interruption in the development of the cartilage of the epiphyses (ends ) Of bones. It mainly affects the long bones, which grow faster, 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 average. Therefore, schooling can be carried out in standard centers and a special school is not necessary.

Causes of achondroplasia

Achondroplasia is the most common cause of non-fatal 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 of the FGFR3 gene located on the short arm of chromosome 4. In most cases (over 95%) the parents are healthy (they do not have the disease) and spontaneous mutations appear in the child on said chromosome, leading to disease expression.
  • Because genetic inheritance: probability that the child suffers from it is 50%. If both parents are affected, then the probability rises to 75% of the total.

Inheritance is autosomal dominant , that is, with the only affectation of only 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 chromosome 4 affected) is lethal.


Symptoms besides dwarfism

The phenotype (physical appearance) is very characteristic. These people have:

  •  Short stature or dwarfism . At birth, the newborn’s size is within normal standards, but final height will be affected.
  • Short limbs, especially the femur and humerus. In the upper extremity the forearm is longer than the upper 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 varo’ , or bowed legs and ligamentous laxity in the knees. The feet are small, flat and wide).
  • Smaller hands , with characteristic separation between the fingers causing the so-called “ trident hand ”. Long and narrow trunk (of normal length).
  • Dorsal kyphosis (hunchback in the mid-vertebral area)
  • Lumbar hyperlordosis (abnormal curve, forward, in the lowest part of the spine) and, sometimes, stenosis -narrowing- of the spinal cord canal, which compresses the spinal cord.
  • Macrocephaly (increased head diameter) with brachycephaly (wide and short skull), prominent forehead, midfacial hypoplasia (small face) and nose with a characteristic “saddle” shape (flattened back of the nose).
  • Tooth malocclusion.

How is it diagnosed?

Prenatal diagnosis through the use of 3D and 4D ultrasound allows greater accuracy when diagnosing skeletal bone dysplasias, in which the length of the femur is routinely measured in relation to the fetal cranial biparietal diameter. Also, bone X -ray is useful to confirm the diagnosis.

Confirmation of the disease is done by genetic study of cell samples obtained by amniocentesis or chorion biopsy .

Do you have treatment?

There are currently no curative treatments available for this disease. However, it should be noted that surgical treatment of bone lengthening at the level of the limbs has been used in some cases, obtaining disparate results.

Treatment is aimed at alleviating difficulties . Medical care must be multidisciplinary, made up of various specialists in different fields:

  • geneticists
  • Pediatricians
  • Traumatologists
  • Psychologists-psychiatrists
  • Nutritionists
  • occupational therapy
  • Social care

In addition, it is a comprehensive treatment 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 added 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.
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