Achondroplasia: symptoms, causes and treatments

There are a large number of elements in which different human beings can differentiate ourselves. When it comes to physique, some of the clearest and most obvious examples are the color or properties of the eyes, hair or skin, or weight or height.

Unlike what happens with aspects such as personality or different cognitive abilities, these characteristics are determined mainly at the genetic level, as in the case of the propensity to suffer from some diseases. In fact, it is not uncommon for some genetic conditions to give rise to unusual phenotypes or body shapes.

An example of this is achondroplasia, one of the main causes of the appearance of the condition known as dwarfism. And it is about this genetic alteration and its different effects that we are going to talk about throughout this article.

• Related article: "Fragile X syndrome: causes, symptoms and treatment"

What is achondroplasia?

It is called achondroplasia a a disease of genetic origin which is one of the main causes of dwarfism worldwide.

Although it is relatively well known among the population, the truth is that it is an alteration considered rare, occurring only in around 2.5 out of every 100,000 births in Spain and 1 in every 25,000 births worldwide. It is a chondrodysplasia, a type of alteration that involves irregularities or delays in the formation of cartilage.

Symptoms

In the case of achondroplasia, throughout the development of the subject a problem is generated in the cells that allow bone growth and the transformation of cartilage to bone. This causes an accelerated calcification of the bones to appear that prevents these, and especially those of the extremities, from developing up to the usual measures.

This means that achondroplasia generates rhizomelic dwarfism (in the bones of the forearm and thigh), in which the trunk has normative measures while the limbs stop growing along.

Another symptom of achondroplasia is macrocephaly, with frontal prominence and hypoplasia of the middle third of the face. This means that generally people who suffer from this alteration have a relatively large head compared to the rest of the body, as well as a more prominent forehead or front of the face.

Brachydactyly also occurs, so that the fingers and toes and their bones are much shorter than usual (although general and except in some cases it does not have to affect the functionality of the hand), and hyperlordosis or extreme curvature of the spine vertebral.

Far from being a condition that affects only visually or aesthetically, the truth is that achondroplasia is an alteration that can lead to a host of health problems and complications. Although at the intellectual level there is usually no type of alteration (achondroplasia per se does not generate cognitive level alterations), the truth is that there is usually a certain delay in the development of motor skills.

There is also usually hypotonia and greater ease to fatigue. Likewise, it is not uncommon for problems such as obstructive sleep apneas to appear, as well as otitis that can affect auditory perception. Also there is an increased risk of neurological and cardiovascular problemss, in addition to a tendency to obesity. Lastly, those with achondroplasia are often at higher risk of respiratory infections and conditions.

More serious but also less frequent are alterations such as compression of the cord and the increased possibility of suffering hydrocephalus (An excess or accumulation of fluid in the brain that could threaten the life of the subject or that could generate intellectual disability). In fact, there is a relevant risk of mortality during childhood due to this type of complications, as well as due to airway obstruction. In homozygous cases, achondroplasia is usually fatal as early as the fetal period.

However, if complications do not occur, the life expectancy and intellectual capacity of people with achondroplasia are not different from those of the rest of the population without this alteration.

Difficulties in other vital areas

The affectation of achondroplasia does not only occur at the health level, but can also involve the appearance of different difficulties in the day to day, damaging the quality of life of the person affected.

For example, most infrastructures or even furniture are usually designed for people with a much higher stature, so the simple act of sitting in a chair or driving a car represents a difficulty unless you have the right support.

It is also common for people with achondroplasia to tend to fatigue more easily, something that can make it difficult to carry out various work and leisure activities.

The quality of sleep for these people may decrease if they suffer from obstructive apnea. In case of pregnancy, women with achondroplasia usually need to resort to caesarean section, due to the small size of their pelvic bones.

In addition to this and especially during child development and adolescence, people with this disorder may encounter difficulties at the social level and suffer isolation, harassment, ridicule, humiliation or simply unwanted attention from others. Likewise and as a consequence of this, in some cases problems of anxiety or depression also tend to appear.

Causes of this alteration

Achondroplasia is, as we have seen previously, a medical condition of genetic origin. Specifically, it has been observed the presence of mutations in the FGFR3 gene (on the short arm of chromosome 4), which is fibroblast growth factor receptor 3.

This gene participates in the growth of bones and the transformation of cartilage into bone, being its mutation the one that generates the mentioned accelerated calcification of the bones and a blockage of their growth due to insufficient differentiation of the tissue.

Although it can be hereditary, and generally in parents with achondroplasia there is a 50% risk of transmitting it and having autosomal dominant inheritance, in general the vast majority of cases are usually new-onset mutations of de novo. I mean, usually appears as a spontaneous mutation in the subject's genome, without the parents having to suffer from the same problem.

Do you have treatment?

Achondroplasia is a genetic and congenital medical condition and as such it does not have a curative treatment. However, it is possible and may be necessary treatment from a multidisciplinary approach in order to correct possible complications and prevent the appearance of disabilities or difficulties in daily life, both in children and in Adults.

To begin with, in the event of hydrocephalus or spinal cord compression, it is essential to act as quickly as possible in order to correct the problem and avoid complications or serious dysfunctions, employing surgical interventions if necessary to it. The goal would be to reduce intracranial pressure and / or drain excess fluid in case of hydrocephalus or decompress and correct spinal problems. Growth hormone treatment has occasionally been used, as well as interventions to correct the curvature of the extremities.

Beyond the treatment so far described, it will be very important the inclusion of physical therapy and the performance of exercises and practices to stimulate mobility and allow to adjust and strengthen posture and muscles. It may also be necessary to work on fine and gross motor skills, in order to facilitate the development of basic skills on a day-to-day basis.

In some cases speech therapy work may be necessary, especially if there are hearing or speech problems. Nutrition should also be worked on in order to prevent possible cardiovascular or respiratory problems that could appear in the event of obesity or poor diet.

Finally also at a psychological level, professional intervention may be necessary, especially when there are anxiety or depressive symptoms.

You can work on self-esteem and self-concept, cognitive restructuring to modify dysfunctional beliefs, management of stress and anger or the presence of difficulties in the day to day derived from both physical problems and possible problems at the Social. Boosting self-esteem and autonomy is also of great help.

At an educational level, the aids that these people may need should be offered, so as to allow their performance and integration in these areas. The provision of adjusted aids may include the use of support material or the adaptation of the person's curriculum. Also at work level, people with achondroplasia may require adaptations, mainly related to ergonomics and physical difficulties of these people.

Bibliographic references:

• Krakow, D. (2018). FGFR3 disorders: thanatophoric dysplasia, achondroplasia, and hypochondroplasia. In: Copel JA, D'Alton ME, Feltovich H, et al, eds. Obstetric Imaging: Fetal Diagnosis and Care. 2nd ed. Philadelphia, PA: Elsevier: chap 50.
• NIH (2017). Achondroplasia. Medline Plus. [On-line]. Available in: https://medlineplus.gov/spanish/ency/article/001577.htm.
• Orphanet Inserm (2017). Achondroplasia. Orphanet Encyclopedia of Disability. [On-line]. Available in: https://www.orpha.net/data/patho/Han/Int/es/Acondroplasia_Es_es_HAN_ORPHA15.pdf.