Ehlers-Danlos Syndrome Hyperextensible Skin

A 22-year-old woman with lifelong joint hypermobility, recurrent spontaneous dislocations, and chronic musculoskeletal pain presents to the dermatology clinic. On examination, the structure marked **A** in the diagram—marked hyperextensibility of the dorsal hand and forearm skin stretched >4 cm with immediate elastic recoil—is noted. She also has thin translucent skin with visible subcutaneous veins and atrophic cigarette-paper scars. Family history reveals similar findings in her mother and maternal grandmother. Genetic testing confirms a COL5A1 mutation. Which of the following best explains the pathophysiology underlying the clinical findings in this patient?