X-linked recessive connective tissue disease caused by impaired copper absorption and transport due to defective Menkes protein (ATP7A).- Leads to ↓ activity of lysyl oxidase (copper is a necessary cofactor) → defective collagen (cross-linking).

- Brittle, "kinky" hair, growth retardation, hypotonia, tortuosity of major arteries.- Low serum ceruloplasmin, decreased serum copper levels.