Achondroplasia is a disease that is caused by a single gene mutation. In patients with this unit, the main thing that draws attention is shortage of growth, but there are definitely more symptoms of achondroplasia - they include, among others, shortening the length of the limbs and reducing the length of the fingers. Currently, there is no cure for achondroplasia, but it is reassuring that patients suffering from this disease have a life expectancy comparable to the general population.

Achondroplasiais a genetically determined rare disease. Data as to the frequency of this unit's occurrence vary between sources, but one thing can be sure: achondroplasia is not a common disease, as it occurs in 1 in 40,000 to 1 in 15,000 live births[1 ] . As for the gender of people suffering from achondroplasia, there is no noticeable tendency for this unit to occur more often depending on gender - in women and men achondroplasia is found with a similar frequency.

Achondroplasia: causes

Achondroplasia occurs as a result of genetic mutations. This disease is caused by mutations related to the FGFR3 gene (abbreviation for fibroblast growth factor receptor 3), i.e. the gene for the receptor of the fibroblast growth factor. The product of this gene is involved in the processes related to the reconstruction of cartilage and bone tissue - genetic abnormalities occurring in the course of achondroplasia lead to disorders of endochondral ossification, and this is the essence of the symptoms of achondroplasia.

In the vast majority of cases, even in as many as 90% of all cases of achondroplasia, the disease is caused by a spontaneous mutation in a child[2] . This means that the genetic error occurs in the patient himself, and his parents, in turn, are of completely normal height and do not suffer from achondroplasia themselves. It is not fully known what leads to the appearance of spontaneous mutations leading to achondroplasia, one of the factors that may contribute to their occurrence is the advanced age of the father (over 35 years).

In the remainder of achondroplasia cases, the disease is brought about by inheriting the mutant gene from the parent (or parents) with achondroplasia. In such a situationthe disease is inherited autosomal dominantly. This means that if one parent suffers from achondroplasia, the risk of developing the disease in his offspring is 50%. If a couple becomes pregnant and both partners have achondroplasia, then they have a 50% chance of having a child with achondroplasia, a 25% chance that their child will be he althy, and a 25% risk that their child will become a carrier. both copies of the mutated gene (and such a situation in the case of achondroplasia is lethal, which means that it leads to the death of the fetus).

Achondroplasia: symptoms

The first disorders related to a child suffering from achondroplasia are visible from the moment of his birth (and often even earlier, because the first changes can be observed in patients even during intrauterine life). The most common symptoms of achondroplasia include:

  • disproportionate (in relation to the body) limbs, in addition, within the limbs there is noticeable shortening of their proximal parts (closer to the body)
  • increased head circumference (macrocephaly) accompanied by an excessively bulging forehead
  • nasal collapse
  • very short fingers
  • narrowing of the chest
  • small hands (micromelia) with a specific position of the fingers, so that the hand of patients with achondroplasia may resemble a trident

The abovementioned disorders, observed immediately after birth, in the case of achondroplasia, may also be accompanied by a reduction in muscle tone (hypotonia). In addition, children with this unit are more likely to develop hydrocephalus - this condition may require treatment, therefore, in newborns with achondroplasia, imaging tests are performed to confirm or rule out the accumulation of excessive fluid in the skull.

As a child with achondroplasia grows older, further symptoms of this disease may become more and more evident. Characteristic for achondroplasia is a shortage of growth - this unit is one of the causes of dwarfism and in its course men achieve an average height of about 131 centimeters, while women with achondroplasia measure about 124 centimeters[3] .

The symptoms of achondroplasia described so far are, unfortunately, not the only problems associated with this individual. Well, patients with achondroplasia tend to have excessively deepened spine curves, and they also have an increased risk of spinal stenosis. Due to defects in the construction of the cageIn addition, due to anatomical differences in the structure of the head structures, patients with achondroplasia are more likely to suffer from laryngological diseases, such as recurrent infections of the middle ear. Obesity is another problem that is more frequently reported in the achondroplasia population.

One aspect needs to be emphasized - just as achondroplasia is associated with many different disorders, so typically they do not concern the functioning of the nervous system - in patients with achondroplasia their intellect is usually not abnormal.

Achondroplasia: diagnosis

Achondroplasia can be suspected on the basis of the characteristic symptoms of this individual after the birth of a child. Suspicion that the child may suffer from achondroplasia, but it is also possible during pregnancy - the doctor may suggest that there is such a possibility by performing an ultrasound during pregnancy, during which abnormalities suggesting achondroplasia are detected (e.g. unusually large in relation to the gestational age) , dimensions of the baby's head).

The above, however, only describes how achondroplasia can be suspected. The final diagnosis of the disease can be made after genetic tests are carried out, in which mutations characteristic for this individual will be detected.

Achondroplasia: treatment

Currently, there is no method of causal treatment of achondroplasia, i.e. one where it would be possible to eliminate the mutation associated with this disease and remove its effects. In patients with achondroplasia, therapy is implemented primarily when they develop some complications of this unit, such as, for example, significant narrowing of the spinal canal leading to pressure on the spinal cord (where surgical treatment may be performed) or frequent infections of the middle ear (in which patients may be recommended antibiotics).

In some patients with achondroplasia - in order to increase their growth - attempts are made to administer growth hormone preparations to them. At present, however, such a procedure seems controversial because, according to some researchers, the results obtained in this way are hardly satisfactory.

Achondroplasia: prognosis

Achondroplasia can certainly have a significant impact on the lives of patients suffering from it, however, at least one piece of information related to this individual is comforting. The good news in this case is that it is the most common life expectancy of peoplepeople suffering from achondroplasia is not shorter than the life expectancy of people in the general population.

Sources:

[1]National Human Genome Research Institute resources, on-line access: https://www.genome.gov/19517823/learning-about -achondroplasia /[2]National Organization for Rare disorders materials, on-line access: https://rarediseases.org/rare-diseases/ achondroplasia /[3]Materials U.S. National Library of Medicine, on-line access: https://ghr.nlm.nih.gov/condition/achondroplasiadiagnosis

About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

Category:

Genetic diseases