Collagenopathies

Collagenopathies are a group of inherited disorders caused by defects in collagen genes or in the enzymes and processes that synthesize, modify, and assemble collagen fibers. These defects weaken connective tissues and can affect skin, joints, bones, blood vessels, eyes, and kidneys. The spectrum includes disorders caused by mutations in COL genes such as COL1A1 and COL1A2 (osteogenesis imperfecta and related connective tissue disorders), COL3A1 (vascular Ehlers-Danlos syndrome), COL5A1 and COL5A2 (classical Ehlers-Danlos syndrome), COL2A1 (Stickler syndrome, various chondrodysplasias), and COL4A3-5 (Alport syndrome). Some conditions involve other components of the collagen processing pathway, such as enzymes that modify hydroxylation and cross-linking of collagen chains.

Pathophysiology: Defects disrupt triple-helix formation, fibril assembly, or cross-linking, leading to reduced tensile strength and abnormal tissue architecture. The clinical features depend on which tissues express the affected collagen type and the inheritance pattern, which may be autosomal dominant, autosomal recessive, or X-linked.

Clinical features: Patients may have joint hypermobility and recurrent dislocations, skin that is unusually soft, fragile, or prone to bruising, and bone fragility with fractures. Vascular fragility and organ involvement can occur in specific subtypes, particularly vascular Ehlers-Danlos syndrome; eye and ear involvement are seen in other forms such as Stickler or COL4-related diseases.

Diagnosis and management: Diagnosis relies on clinical evaluation, family history, and targeted genetic testing, with skin biopsy or molecular analysis of collagen deposition sometimes used to support the findings. There is no cure; management focuses on reducing complications and improving quality of life through physical therapy, pain management, fracture prevention, wound care, and monitoring for organ involvement. Genetic counseling is often recommended.