Achondroplasia

Achondroplasia is known as congenital chondrodystrophy, Parra-Marie disease, or diaphyseal aplasia. It is a congenital disease that interferes with the bone growth process. The disease affects the skeleton and the skull base. The cause of achondroplasia is the FGFR3 gene mutation (Trotter & Hall, 2005). In some cases, achondroplasia is inherited. In other, it is the result of the new-onset mutations developing. A part of the fetus with this pathology dies in utero. After birth, the signs are apparent in the first days of life: an increased head, short arms, and legs. Subsequently, there is a pronounced lag in the growth of limbs while the trunk is of the normal size. There are valgus and varus deformities of the limbs as well as a spinal deformity. Because of the skeletal pathology, the secondary disorders of the internal organs may develop. Achondroplasia treatment is symptomatic and aimed at the prevention and elimination of gross deformations. Therefore, the paper discusses the etiology, symptoms, and prognosis of achondroplasia as well as treatment plans and organizations and resources for the families suffering from the disease’s impact.

Etiology

The deformation of the bones as a result of genetically determined dystrophy of epiphyseal cartilage is the gist of achondroplasia (Laederich & Horton, 2010, p. 516). Due to the chaotic arrangement of the cells of growing zone, there is a disturbance of the normal process of ossification. As a result, the growth of the bones becomes slower (Trotter & Hall, 2005). It affects only the bone of the enchondral type: tubular bones, the bones of the skull base. The calvarial bones growing from the connective tissue lead to a mismatch between the proportions of the head and the body and also cause characteristic changes in the shape of the skull.

According to Kivi (2015), only about 20% of achondroplasia is inherited. The mutation results from the autosomal predominant inheritance pattern. Thus, only one of the parents needs to transmit the FGFR3 gene that causes achondroplasia. The sporadic form of the disease differs from case to case. Heredity is not relevant in this case. Such mutations can occur under the influence of radiation, extreme temperatures, the formation of chemical compounds, metabolites that cause mutagenic effect, in the human body.

Symptoms

The variation of anatomical proportions is noticeable at birth. A child with achondroplasia has a relatively large head and short arms and legs. Cerebral part of the skull is increased. Occipital and parietal bumps protrude. In some cases, hydrocephalus is possible. The changes of the structure of the facial skeleton result from the improper development of the bones of the skull base (Trotter & Hall, 2005). The eyes of the patients with achondroplasia are located deep in the orbits. There are additional wrinkles near the inner corners of the eyes. Patients have flattened nose with a wide top. The upper jaw also significantly protrudes above the lower one. The lower and upper limbs of patients with achondroplasia are uniformly shortened, mainly due to the proximal segment (hips and shoulders) (Boston Children’s Hospital, n.d.). All segments of the limbs are twisted. Feet are wide and short. In the first months of life of the patients with achondroplasia, fat pads and skin folds are visible. The body is normally developed. The chest is not changed. The belly is jutting forward while the pelvis is tilted backward.

Prognosis

The prognosis depends on the severity of the disease. Most people with one mutated copy of the gene have a normal life expectancy. Cognitive functions are normal as well, although some children may exhibit a mild deficit in terms of the performance of visual-spatial tasks. In the first year of life, death may occur due to the increased pressure on the spinal cord, the craniocervical junction anomalies. The patients who have two defective copies, one copy from each parent, usually die few weeks or months after birth.

Infants with achondroplasia are more likely to suffer from sudden death during sleep than their peers. “In individuals aged 5-24 years, central nervous system (CNS) and respiratory abnormalities are the common causes of death. In persons aged 25-54 years, cardiovascular problems are the most frequent causes of death” (Parikh, 2016). It is assumed that the cause of death in these cases is the compression of the medulla oblongata and upper spinal cord because of the shape and size anomalies of the foramen.

There are a number of characteristics of achondroplasia. Hip bones are bent, and the upper limbs are also distorted, particularly in the area of ​​the forearm. In addition, there are pronounced changes in the head and the facial skeleton: increased cerebral part of the skull, projecting and overhanging forehead, deep nasal bridge, and visible malocclusion. There is also a possibility of strabismus development. Moreover, the patients with achondroplasia are prone to obesity. Due to the dissolution of the nasal passages, otitis and conductive hearing loss are developed. Because of the obstruction of the upper airway, the signs of respiratory distress can be detected (Boston Children’s Hospital, n.d.). The narrowing of the spinal canal is often observed in the patients suffering from achondroplasia. It usually occurs in the lumbar region, and the least, in the cervical or thoracic spine. Sensitivity disorders, paresthesias, and pain in legs may be developed. In more severe cases, the patients may experience the dysfunction of the pelvic organs, paresis, and paralysis.

Treatment Plan

The complete recovery of patients with achondroplasia is impossible even considering the possibilities of modern orthopedics. Attempts have been made to administer treatment with growth hormone. However, the reliable evidence of the effectiveness of this technique could not be obtained in the case of achondroplasia. At an early age, conservative therapy that is aimed at strengthening the muscles and preventing limb deformity is given. Physical therapy and massage are prescribed for the patients with achondroplasia (Stöppler, 2015). The patients are also recommended to wear special orthopedic shoes. Moreover, the obesity prevention strategies are developed.

Surgical intervention in the case of achondroplasia is done when the deformation of limbs and narrowing of the spinal canal are expressed (Stöppler, 2015). To correct the deformation, osteotomy is performed. Laminectomy is performed to correct spinal stenosis. In some cases, surgeries are also undergone to increase the growth. Limb lengthening in achondroplasia is usually conducted in two stages. First, the thigh is elongated with one hand and the shin, with the other. Then, a surgery in the remaining segments is performed.

There are many researchers in the world who pay attention to studying the problems of achondroplasia. BioMarin is one of such research companies in California (Okenfuss, 2012). Its key mission is to develop drug treatment for genetic conditions: “BioMarin has developed a drug and they believe it will increase bone growth in individuals with achondroplasia” (Okenfuss, 2012). There are a number of other resources and organizations that provide help and assistance to the patients with achondroplasia. They are the European Skeletal Dysplasia Network, the Genetic and Rare Diseases Information Center, the Human Growth Foundation, Little People of America, the MAGIC Foundation, the March of Dimes, the NIH of Arthritis and Musculoskeletal and Skin Diseases, and the Restricted Growth Association (National Organization for Rare Disorders, n.d.).

Conclusion

To conclude, achondroplasia is a genetic disease that is associated with the shortening of the limbs whereas the trunk is of normal size. Characteristic features are short stature, curved spine, saddle nose, and a relatively large head with prominent frontal tubercles. There are no ways to completely cure achondroplasia and restore the growth and proportions of the body. Nevertheless, the existing treatment is aimed at minimizing the negative effects of the disease.