Van Buchem&;s syndrome is characterized by all except:
**Core Concept**
Van Buchem's syndrome is a rare condition characterized by an abnormality in the calcification of the mandible, leading to a distinctive radiographic appearance. This condition is often associated with a specific genetic mutation affecting the gene responsible for the regulation of mineralization.
**Why the Correct Answer is Right**
Van Buchem's syndrome typically presents with the following features: a characteristic "salt and pepper" appearance on radiographs, due to the irregular calcification of the mandible; the presence of a normal or even low serum calcium level; and an elevated alkaline phosphatase level, indicating an increase in bone turnover. The condition is often diagnosed in early childhood and may be associated with other systemic abnormalities.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as Van Buchem's syndrome typically does not present with an elevated serum calcium level, which is more characteristic of hyperparathyroidism or other conditions affecting calcium homeostasis.
**Option B:** This option is incorrect as the "salt and pepper" appearance on radiographs is a hallmark of Van Buchem's syndrome, not a feature of normal bone development or other conditions.
**Option C:** This option is incorrect as the genetic mutation affecting the gene responsible for mineralization regulation is a key factor in the pathogenesis of Van Buchem's syndrome, not a feature of normal bone development or other conditions.
**Clinical Pearl / High-Yield Fact**
Van Buchem's syndrome is a rare genetic disorder that highlights the importance of considering systemic abnormalities when evaluating radiographic findings in children. It is essential to recognize the characteristic "salt and pepper" appearance on radiographs and to investigate for associated systemic abnormalities.
**Correct Answer: D.**