Malignant Infantile Osteopetrosis
What is malignant infantile osteopetrosis?
Osteopetrosis is a rare skeletal disorder where a person’s bones become too dense, and are easily fractured and broken. This happens when new bone grows faster than old bone can be removed. Too dense bone can negatively impact the body in serious ways. Malignant infantile osteopetrosis, also known as severe malignant osteopetrosis and marble bone disease, is a very severe form of osteopetrosis.
Patients with malignant infantile osteopetrosis are born with the condition. It is apparent at birth or in early infancy. Approximately 8 to 40 children are born in the United States with this condition per year. Males and females are affected equally.
What are the symptoms of malignant infantile osteopetrosis?
The following are some of the characteristic symptoms of malignant infantile osteopetrosis:
- Bone fractures
- Teeth and jawbone infections
- Abnormally large head
- Facial paralysis
- Atrophy of the retina, widely spaced eyes, crossed eyes, and/or blindness
- Hearing loss
- Frequent infections
- Slow growth
- Failure to thrive
- Low blood cell levels (anemia)
What causes malignant infantile osteopetrosis?
Human traits are inherited from one’s father and mother. They each contribute a gene, which interacts with the other. Malignant infantile osteopetrosis is inherited in an autosomal recessive pattern, which means that both parents need to pass down a copy of the defective gene for the condition to occur. The mutated gene responsible for this condition has been located on the long arm of chromosome 11 (more specifically, on 11q12-q13).
Bones become defective in this condition because there aren’t enough osteoblast cells being produced. Osteoblasts aid in the production of bone by maintaining the balance between formation and loss of calcium in the bone. When there isn’t enough of those cells being produced, bone growth is stunted.
How is malignant infantile osteopetrosis diagnosed?
Malignant infantile osteopetrosis is diagnosed using the following procedures:
- Clinical evaluation
- Detailed medical history
- Blood tests
- CAT scan
- Hearing tests
- Vision tests
What are the treatments for malignant infantile osteopetrosis?
Treatment for malignant infantile osteopetrosis, includes but is not limited to:
- Interferon gamma-1b, an injected drug that delays progression of the disease
- Bone marrow transplant
- Vitamin D supplements (Calcitriol) to help reduce bone density
- Medication to improve blood cell levels
- Good nutrition
- Physical therapy
- Occupational therapy
- Treatment for fractures
- Regular doctor visits to monitor hearing and vision
- Regular dentist visits
- Genetic counseling
Where can I find out more about malignant infantile osteopetrosis?