Achondroplasia is the most common form of disproportionate dwarfism, a genetic condition impacting bone development, especially in the long bones of the limbs. It results from a specific change in the FGFR3 gene, which regulates bone growth. While there is no cure, various treatments and interventions manage symptoms, enhance quality of life, and address health challenges.
Pharmacological Therapies
Drug-based treatments influence bone growth directly. Vosoritide (Voxzogo) is a notable advancement. This medication targets the overactive FGFR3 pathway, a result of the genetic mutation in achondroplasia. By inhibiting this overactivity, vosoritide helps restore a more balanced rate of bone growth.
The medication mimics C-type natriuretic peptide (CNP), a natural human peptide that promotes endochondral ossification, the process of cartilage converting into bone. Clinical studies show vosoritide increases growth velocity in children with achondroplasia. It received approval in the United States and Europe for use in children, typically from around 2 years of age until growth plates close, which occurs around late adolescence.
Growth hormone has been explored as a treatment for achondroplasia in the past. While it can increase height in some conditions, its effectiveness in achondroplasia has been limited. It does not address the underlying genetic mechanism affecting bone development in the same targeted way as newer therapies like vosoritide, and has not shown the same significant impact on growth velocity or proportionality.
Surgical Interventions
Surgical procedures play a significant role in managing the physical aspects of achondroplasia and addressing specific complications. Limb lengthening surgery increases overall height and improves limb proportionality. This involves cutting the bone and gradually separating segments using external fixators or internal rods, stimulating new bone formation. The process requires a substantial commitment from the individual and their family, often spanning several months to years for completion. Potential risks include infection, nerve damage, joint stiffness, and non-union of bone segments.
Spinal decompression and fusion surgeries address spinal cord compression. Infants may experience compression at the foramen magnum, the opening at the base of the skull, affecting breathing and neurological function. In older individuals, lumbar spinal stenosis, a narrowing of the spinal canal, can compress nerves, causing pain or weakness. These surgeries relieve pressure on the spinal cord or nerves, preventing further neurological damage.
Ventricular shunting procedures are performed for hydrocephalus, an accumulation of cerebrospinal fluid in the brain. A shunt is a thin tube inserted to drain excess fluid from the brain to another body part, typically the abdomen, where it is absorbed. Other orthopedic surgeries may correct skeletal issues like bowed legs through osteotomies, realigning bones to improve gait and joint mechanics.
Managing Associated Health Issues
Individuals with achondroplasia often face several associated medical complications that require ongoing management, distinct from primary skeletal treatments. Ear, nose, and throat issues are common, particularly recurrent ear infections, or otitis media. The structure of the Eustachian tubes can predispose individuals to fluid buildup, leading to frequent infections. Management often involves close monitoring, antibiotic treatment, or the insertion of ear tubes to facilitate drainage and prevent hearing loss.
Sleep apnea is another concern, potentially caused by upper airway obstruction or central neurological factors. Assessment involves a sleep study to determine apnea type and severity. Treatment options range from continuous positive airway pressure (CPAP) therapy to surgical interventions like adenoidectomy or tonsillectomy, which clear airway passages. Ongoing monitoring for hydrocephalus and spinal cord compression is important throughout life, with regular imaging and neurological assessments.
Weight management is also a significant aspect of care. Due to shorter stature and altered body proportions, individuals with achondroplasia have an increased risk of obesity. Maintaining a healthy weight reduces excessive strain on joints, particularly in the hips, knees, and spine, which are prone to complications. Dietary guidance and regular physical activity support a healthy weight.
Supportive Care
Supportive care encompasses non-medical and non-surgical approaches designed to enhance quality of life and promote functional independence. Physical therapy and occupational therapy are integral, beginning in infancy to support motor skill development. Physical therapists help improve strength, flexibility, balance, and coordination, assisting children in reaching developmental milestones. Occupational therapists focus on adapting daily activities and environments to foster independence in tasks like dressing, eating, and schoolwork.
Adaptive strategies and equipment are used to navigate a world designed for average height individuals. This includes modified furniture (e.g., lower tables and chairs) and specialized tools to reach items or operate controls. Environmental adaptations at home, school, and work, such as step stools, extended light switches, and customized vehicle controls, help individuals participate fully.
Psychosocial support addresses the emotional and social well-being of individuals and their families. Connecting with peer support groups or advocacy organizations provides a sense of community and shared experience. Addressing self-esteem, promoting positive body image, and facilitating social integration are important for overall mental health. Regular medical check-ups and consultations with a multidisciplinary team of specialists (including geneticists, orthopedists, neurologists, and audiologists) are necessary throughout life to monitor health and address emerging issues.