Genetics

Question 1

Osteogenesis Imperfecta

Answer 1

Mut. COL1A (collagen type 1)
Cannot form proper triple helix

Brittle bones, blue sclera, hearing loss

Question 2

Ehlers Danlos Syndrome

Answer 2

Classic: defective type 5 collagen (COL5A)
Joint hypermobility, mitral valve prolapse, hyperextensible skin

Vascular: defective type 3 (COL3A)
Berry aneurysms, intestinal perforation

Question 3

Marfan Syndrome

Answer 3

Deficient fibrillin (Mut. FBN1)

Tall, long fingers, pectus excavatum, cataracts, dislocation of lens, aortic aneurysms and dissection

Question 4

Pleiotropy

Answer 4

One gene = multiple phenotypic effects and traits

Question 5

McCune Albright Syndrome

Answer 5

GNAS mut –> continuously active adenylyl cyclase
Form of mosaicism (is NOT inherited)
Cafe au lait spots, bone fractures, precocious puberty

Question 6

Symptoms and cause of Down Syndrome

Answer 6

Meiotic non-disjunction

Flat facial profile, protruding tongue, small ears, and endocardial cushion defects