THANATOPHORIC DYSPLASIA, HYPOCHONDROPLASIA, AND ACHONDROPLASIA ARE CAUSED BY MUTATIONS IN WHICH GENE

• A. COMP (cartilage oligomeric matrix protein)
• B. FGFR3 (fibroblast growth factor receptor 3) ✓
• C. COL1A1
• D. MATN3 (matrilin-3)
• E. CDMP1 (cartilage-derived morphogenetic protein 1)

Thanatophoric dysplasia, hypochondroplasia, and achondroplasia are all genetic disorders that affect bone growth and development. These conditions are caused by mutations in the FGFR3 (fibroblast growth factor receptor 3) gene.

FGFR3 is a gene that provides instructions for making a protein involved in the development and maintenance of bone and brain tissue. Mutations in this gene can lead to overactivity of the FGFR3 protein, which disrupts normal bone growth and development.

Understanding the Conditions:

• Thanatophoric Dysplasia: Thanatophoric dysplasia is a severe skeletal disorder characterized by extremely short limbs, a narrow chest, and underdeveloped lungs. It is usually lethal shortly after birth due to respiratory insufficiency.
• Hypochondroplasia: Hypochondroplasia is a milder form of skeletal dysplasia that results in short stature, particularly affecting the limbs.
• Achondroplasia: Achondroplasia is the most common form of dwarfism characterized by disproportionately short stature with short arms and legs.

Genes Associated with the Conditions:

The mutations responsible for these conditions are found in the FGFR3 (fibroblast growth factor receptor 3) gene. This gene provides instructions for making a protein that plays a crucial role in bone development and growth. Mutations in FGFR3 can lead to overactivity of the protein it encodes, which disrupts normal bone growth and development, resulting in the characteristic features of these skeletal dysplasias.