Causes and risk factors
Mutations in the FGFR3 gene cause achondroplasia. The FGFR3 gene gives instructions for making a protein which is responsible for the development and maintenance of bone and brain tissue. This protein limits the formation of bone from cartilage, i.e., ossification, particularly in the long bones, i.e., the cartilage at the ends of long bones fail to convert into bones. Two specific mutations in the FGFR3 gene are responsible for achondroplasia. Risk factors include children of a parent with achondroplasia, children of normal-sized parents who carry a mutated FGFR3 gene, advanced paternal age causing spontaneous mutations, and spinal stenosis. Hydrocephalus increases the risk of achondroplasia.
Clinical presentation
The following are the most common symptoms of achondroplasia: Short arms and legs, with the upper arms and thighs shorter than the forearms and lower legs. Bowing of legs, flat feet that are short and broad are seen. Large head size with prominent forehead and a flattened nasal bridge. There is crowding or misalignment of teeth. Lordosis – curved lower spine is observed. Kyphosis – development of a small hump near the shoulders that usually goes away after the child begins walking. Small vertebral canals may lead to spinal cord compression in adolescence. Trident hand – extra space between the middle and ring fingers. Patient presents with poor muscle tone, loose joints, frequent middle ear infections which may lead to hearing loss, delayed milestones. However, intelligence remains normal. There can occur sudden death. Occasionally children with achondroplasia may die suddenly in infancy or early childhood in their sleep due to compression of the upper end of the spinal cord, which interferes with breathing.
Investigation
Medical history by the patient and clinical examination by the doctor helps in diagnosis. Achondroplasia can be diagnosed before birth by fetal ultrasound or after birth by complete medical history and physical examination. DNA testing is now available before birth to confirm fetal ultrasound findings for parents who are at increased risk for having a child with achondroplasia.
Treatment
There is currently no treatment to cure this condition. Treatment with human growth hormone effectively increases bone growth rate, at least in the first year of life. Surgery is required to correct specific skeletal deformities. Spinal fusion, laminectomy, osteotomy are common procedures that contribute further to the treatment.
Other Modes of treatment
The other modes of treatment can also be effective in treating achondroplasia. Homoeopathy is a science which deals with individualization and considers a person in a holistic way. This science can be helpful in combating the symptoms. Similarly, the Ayurvedic system of medicine, which uses herbal medicines and synthetic derivates, is also found to be effective in treating achondroplasia.
Facts and figures
It occurs among 1 in 15,000-40,000 newborn infants.
