EM: Clinical disorders due to Defective fibers

Question 1

Ehlers-Danlos IV

Answer 1

Mutation in COL3A1 gene encoding type III colagen (reticular fibers)

Varicose veins, aortic rupture, intestinal rupture

Question 2

Ehlers-Danlos VI

Answer 2

Defective hydroxylation of lysine thereby destabilizing the strength of the collagen

Hyperelasticity of skin, rupture of eyeball

Question 3

Ehlers-Danlos VII

Answer 3

Mutations in COL1A1 and COL1A2 genes encoding type I collagen

Joint dislocation and hypermobility of joints

Question 4

Scurvy

Answer 4

Tropocollagen molecules cannot aggregate into fibrils due to decreased hydroxylation of proline caused by a deficiency in vitamin C

Gum ulceration and hemorrhages

Question 5

Osteogenesis Imperfecta

Answer 5

Mutations in COL1A1 gene lead to a reduction in synthesis of type I collagen

Spontaneous fractures and cardiac insufficiency

Question 6

Strickler syndrome

Answer 6

Mutation in COL2A1 gene encoding for type II collagen

Myopia, hypoplasia of mandible, arthritis

Question 7

Marfan syndrome

Answer 7

Mutation of fibrillin 1 gene located on chrom. 15

Aortic aneurysm or rupture, myopia, detached lens, skeletal defects (long thin arms, legs, toes, and fingers) pectum excavatum, scoliosis