Introduction
In an autosomal recessive disease, a person inherits two altered genes, sometimes called mutations. A person receives one from each parent. Since only one gene is altered, it rarely affects the health of the parents in their case. Two carriers have a 25 percent chance of having an unaffected child with two genes that are unaffected. There is a 50 percent chance of having an unaffected child who is also a carrier. There is a 25 percent chance of having an affected child with two gene alterations. Hence two copies of the gene must be available in order for the trait to develop. SOST (Sclerostin) gene - Van Buchem's disease is a disorder of bone development characterized by excessive bone formation (hyperostosis).
As a result of hyperostosis, bones throughout the body are denser and wider than normal, particularly the bones of the skull. Affected individuals typically have an enlarged jaw with misaligned teeth. People with this condition may also have a sunken appearance in the middle of the face (midface hypoplasia), bulging eyes with shallow eye sockets (ocular proptosis), and a prominent forehead. People with this condition often experience headaches because the increased thickness of the skull bones increases pressure on the brain. The excessive bone formation seen in this condition seems to occur throughout a person's life, so the skeletal features become more pronounced over time. However, excessive bone growth may only occur in certain areas.
What Is Van Buchem Disease?
Van Buchem disease (VBD) is a very rare hereditary bone condition, also known as hyperostosis corticalis generalisata. The disease is mainly characterized by an enlarged mandible and thickening of the skull. It is a very rare condition, with less than thirty cases of this condition having been reported so far, and most of those conditions have been from Dutch ancestry. In this condition, abnormal bone growth can pinch (compress) cranial nerves that exit the brain and go to various areas of the head and neck, can cause loss of vision, decreased sense of smell (hyposmia), or loss of smell (anosmia). Abnormal bone growth can cause life-threatening complications when it presses on the part of the brain that connects to the spinal cord (brain stem). People with Van Buchem’s disease are usually of average height and do not have nail abnormalities. Affected individuals tend to have mild compression of cranial nerves, resulting in mild neurological features. People with Van Buchem’s disease usually present with skeletal features during childhood or adolescence.
What Are the Causes of Van Buchem Disease?
Van Buchem’s disease is a homozygous recessive disease. Deletions and mutations affecting the SOST gene alter expression in osteoblasts (bone-forming cells), resulting in an inability to stop osteoblastic bone formation. Patients with Van Buchem’s disease have elevated serum alkaline phosphatase levels (protein enzyme related to the bone) in 50 percent of cases.
What Are the Symptoms of Van Buchem Disease?
The signs and symptoms of Van Buchem’s disease include the following:
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Paralysis of the face.
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Neuralgic pain.
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Hearing loss.
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Visual problems.
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Increased thickness of jaw and skull.
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Fusion of long bone.
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Decreased sense of smell.
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The sunken appearance of the middle face.
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Bulging eyes due to shallow eye sockets.
How Is Van Buchem Disease Diagnosed?
The diagnosis of Van Buchem’s disease is based primarily on abnormalities of the skull and mandible, facial nerve involvement, and skeletal radiography.
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X-Ray - The first clue to Paget's disease (a chronic bone disorder of excessive breakdown and regrowth) of bone is often an abnormality he finds on X-rays for other reasons. X-rays of your bones can show areas of bone loss, bone hypertrophy (increased bone thickness due to an injury or disorder), and deformities characteristic of diseases such as the bending of long bones.
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Bone Scan - During a bone scan, radioactive material is injected into the body. This material migrates to the most affected areas of the bone, and these appear brighter in scanned images.
What Is the Treatment of Van Buchem Disease?
If there are no symptoms, no treatment is needed. However, when the disease is active (indicated by elevated levels of alkaline phosphatase), it affects high-risk areas in the body, such as the skull, ribs, and jaw. If a person is having a problem with their skull or spine, even if the patient does not have any symptoms, the doctor may recommend treatment to prevent complications.
What Are the Complications of Van Buchem Disease?
Complications of Van Buchem’s disease include the following:
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Deafness.
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Visual problem.
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Severe headaches.
Conclusion
Van Buchem’s disease (VBD) is a rare osteosclerotic dysplasia (congenital disorder of bone sclerosis) caused by a lack of regulatory elements in the SOST gene, which encodes sclerostin, which causes dysregulation of bone formation. The main features of this condition are enlarged and excessively thickened bones of the mandible, skull, ribs, and fused long bones. Since it is a hereditary condition, there is no way to prevent it. It can only be managed with the help of specialists. Early diagnosis in life helps in better outcomes of the condition.
