All you need to know about: Cleidocranial Dysplasia (CCD)

Actor Gaten Matarazzo, who plays Dustin Henderson in the global hit series Stranger Things , has spoken openly about living with Cleidocranial Dysplasia (CCD), a rare genetic disorder that affects bone and dental development. His visibility has helped bring public attention to a condition that is uncommon, lifelong and frequently misunderstood and, in many cases, diagnosed late. For clinicians, CCD can be one of those rare genetic disorders that can slip through routine health systems, particularly when symptoms are mild or fragmented across specialties. What is Cleidocranial Dysplasia? Cleidocranial Dysplasia is a congenital genetic disorder that interferes with the normal formation of bones and teeth. It is most commonly caused by mutations in the RUNX2 gene, a key regulator of osteoblast differentiation -- the cells responsible for bone formation. The gene is especially important for intramembranous ossification, the process by which flat bones such as the skull, face and collarbones develop directly from connective tissue rather than through a cartilage stage. When this pathway is disrupted, bones that rely on it develop incompletely or abnormally. As a result, CCD primarily affects the skull, clavicles (collarbones) and dentition. The condition is present from birth and persists throughout life, but its severity varies widely. Some individuals have subtle features that go unnoticed for years, while others experience significant skeletal and dental challenges requiring long-term medical care. How common is CCD globally and in India? CCD is considered a rare disease worldwide. International rare-disease registries estimate its prevalence at approximately 1-9 cases per million people, with many medical references citing an average of around one in a million. Global agencies such as the World Health Organization do not maintain disease-specific prevalence figures for CCD, and studies also emphasise its rarity and the broader difficulty of tracking uncommon genetic conditions across populations. In India, there is no population-level prevalence data for CCD. Most available information comes from isolated case reports and small clinical series published in orthopaedic, dental and genetic journals.. However, clinicians note that underdiagnosis is likely, particularly in regions with limited access to genetic testing, specialised dental care and multidisciplinary clinics. Mild cases may never be formally identified, while others are diagnosed only after years of unexplained dental or skeletal issues. What are the main clinical features? CCD mainly affects bones that develop directly, without first forming cartilage. A key feature is missing or underdeveloped collarbones (clavicles), which lets some people bring their shoulders unusually close together in front of the chest. Another common sign is delayed closure of the skull bones. The soft gaps between skull bones may stay open longer than usual, sometimes into adulthood, leading to a broad forehead or changes in head shape. Dental abnormalities are among the most consistent and clinically significant features. These include delayed loss of baby teeth, delayed or failed eruption of permanent teeth, the presence of extra (supernumerary) teeth, crowding, misalignment and bite problems. Many individuals require complex, staged dental interventions over several years. Other features may include short stature, reduced bone density,...

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