What is Hypochondroplasia / Achondroplasia?
Hypochondroplasia is a genetic skeletal disorder that affects the normal conversion of cartilage into bone. The disorder is characterized by small stature, stocky build, enlarged head, and disproportionately short limbs and extremities. The condition generally becomes evident during early to mid-childhood or early adulthood. Men and women are equally affected by this disorder.
Achondroplasia, also known as achondroplastic dwarfism, is also a genetic skeletal condition similar to hypochondroplasia; however, the clinical features of achondroplasia are more severe and can be noted at birth.
Signs and Symptoms of Hypochondroplasia / Achondroplasia
The signs and symptoms of hypochondroplasia / achondroplasia may include:
Head and Face Abnormalities:
- Slight macrocephaly (enlargement of the head)
- Prominence of the forehead
Trunk Abnormalities:
- Long trunk in comparison to the limbs
- Protuberant abdomen
- Spinal stenosis
- Lumbar lordosis (forward bending of the lumbar spine)
- Limb Abnormalities
Limb Abnormalities:
- Short and stocky limbs
- Outward bowing of knees
- Limited elbow extension and rotation
- Prominent aching of knee, elbows, and ankles
- Mild joint laxity
- Inversion of feet
Mental Abnormalities:
- Intellectual disability
- Learning difficulty
The signs and symptoms of achondroplasia are more pronounced as compared to hypochondroplasia with severe malformations in the spine, pelvis, hands, skull, and facial regions, and neurological impairment.
Causes of Hypochondroplasia/ Achondroplasia
Hypochondroplasia / achondroplasia is usually caused due to a mutation of the fibroblast growth factor receptor-3 gene. The disease is inherited as an autosomal dominant trait, which means a child has a 50% chance of inheriting the condition if one of the parents has the mutated gene. However, the condition may also occur in patients without this specific type of genetic mutation. In such instances, the underlying cause is unclear.
Diagnosis of Hypochondroplasia / Achondroplasia
Diagnosis of hypochondroplasia / achondroplasia is made based on clinical examination to identify characteristic physical features and X-ray studies to assess bone abnormalities.
Treatment of Hypochondroplasia / Achondroplasia
Treatment of hypochondroplasia / achondroplasia depends on the specific symptoms. A multidisciplinary approach may be required involving pediatricians, orthopedists, physical therapists, and other health professionals. The various options may include:
- Genetic counseling
- Growth hormone therapy
- Limb lengthening procedure
- Orthopedic surgery to correct bone and joint abnormalities
- Decompression surgery to create space for brain and spine structures
- Physical therapy
- Occupational therapy
