Which of the following gene mutation occurs in cleidocranial dysplasia:
**Core Concept**
Cleidocranial dysplasia is a rare genetic disorder characterized by skeletal abnormalities, including the partial or complete absence of the clavicles and delayed closure of the cranial sutures. It is a developmental disorder that affects the formation of bones and teeth.
**Why the Correct Answer is Right**
The gene mutation responsible for cleidocranial dysplasia is in the RUNX2 gene, which encodes a transcription factor essential for bone development. Mutations in RUNX2 disrupt the normal development of bones, leading to the characteristic features of cleidocranial dysplasia. The RUNX2 protein regulates the expression of other genes involved in bone formation, such as osteoblast differentiation and matrix mineralization.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the gene mutation associated with cleidocranial dysplasia is not in the RNF135 gene.
* **Option B:** This option is incorrect because the gene mutation associated with cleidocranial dysplasia is not in the GATA3 gene.
* **Option D:** This option is incorrect because the gene mutation associated with cleidocranial dysplasia is not in the FGFR2 gene.
**Clinical Pearl / High-Yield Fact**
Cleidocranial dysplasia is often associated with dental abnormalities, including supernumerary teeth, delayed tooth eruption, and impacted teeth. Patients with cleidocranial dysplasia may also have hearing loss due to the abnormal development of the middle ear bones.
**Correct Answer:** C. RUNX2.