X-linked dominant chondrodysplasia punctata

X-linked dominant chondrodysplasia punctata (CDPX2), also known as Conradi-Hünermann-Happle syndrome, is a rare genetic skeletal disorder caused by mutations in the EBP (emopamil-binding protein) gene located on the X chromosome. This gene encodes an enzyme involved in cholesterol biosynthesis (3-beta-hydroxysteroid-delta-8, delta-7-isomerase). The condition predominantly affects females, as it is typically lethal in affected males before birth. CDPX2 is characterized by stippled calcifications (chondrodysplasia punctata) of the cartilage, particularly visible on X-rays in infancy, along with skeletal abnormalities including asymmetric shortening of the limbs, scoliosis, and short stature. The disease affects multiple body systems beyond the skeleton. Skin manifestations are prominent and follow the lines of Blaschko, including ichthyosis (thick, scaly skin) present at birth or in early infancy, follicular atrophoderma (pore-like depressions in the skin), and patchy areas of hair loss (cicatricial alopecia). Ocular involvement, particularly cataracts, is common and may be present at birth or develop in early childhood. Facial features may include a flat facial profile and a depressed nasal bridge. The severity of the condition is highly variable, even among affected individuals within the same family, likely due to differences in X-inactivation patterns. There is no cure for CDPX2, and treatment is supportive and symptom-based. Orthopedic interventions may be needed for scoliosis and limb length discrepancies. Cataracts may require surgical removal to preserve vision. Dermatologic care is important for managing ichthyosis and other skin manifestations. Regular monitoring by a multidisciplinary team including geneticists, orthopedists, ophthalmologists, and dermatologists is recommended. Early intervention and physical therapy can help optimize developmental outcomes and mobility.

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