Chapter 50 & Marfan Syndrome

Question 1

Marfan syndrome is an inherent disorder that affects the connective tissues in the body. This is caused by:
● a. Genetic mutation in fibrillin
● b. Problem in the collagen synthesis
● c. Elastin deficiency
● d. Chromosomal aberration

Answer 1

A

Question 2

Plays a pivotal role in upholding the strength and structural integrity of connective tissue:
● a. Fibrillin-1
● b. TGf- Beta
● c. TGF-alpha
● d. Fibrillin-2

Answer 2

A

Question 3

Medications for managing Marfan Syndrome which are used to treat high blood pressure:
● a. Angiotensin receptor blockers and angiotensin converting enzymes drugs
● b. Angiotensin converting enzymes drugs and beta blockers
● c. Beta blockers and angiotensin receptor blockers
● d. Beta blockers and angiotensin converting enzymes drugs

Answer 3

C

Question 4

It is a condition characterized by excessive secretion of Growth Hormone during a child’s early years before the epiphyseal plates have been fused:
● a. Acromegaly
● b. Gigantism
● C. Marfan Syndrome
● d. Ehlers-Danlos syndrome

Answer 4

B

Question 5

The following are the functions of the proteoglycans, EXCEPT:
● а. Cell migration and adhesion
● b.Anchoring cells to matrix
● C. Organize water molecules
● d. None of the above

Answer 5

D

Question 6

These are large complexes of negatively charged heteropolysaccharide chains and bind with water, producing the gel-like matrix that forms body’s ground substance:
● a. Proteoglycan
● b. Glycosaminoglycans
● c. Fibronectin
● d. Elastin

Answer 6

B

Question 7

The extracellular matrix contains 3 classes of molecules, Fibronectins and laminins are examples of:
● a. Structural proteins
● b. Protein-polysaccharide complexes to embed the structural proteins
● c. Adhesive glycoproteins to attach cells to matrix
● d. All of the above

Answer 7

C

Question 8

Collagen is rich in proline and glycine which are both important in the formation of the triple-helix strand, Which of the following statement is TRUE?
● a. Proline is found in every third position of the polypeptide chain
● b. Proline residues are part of the repeating sequence
● C. Hydroxylation of proline residues does not require iron and Vit C
● d. Proline facilitates formation of helical conformation of each alpha chain

Answer 8

B

Question 9

A heritable connective tissue disorder or a syndrome wherein joint hyper-mobility is the most prominént symptom:
● a. Marfan
● b. Ehlers-Danlos
● c. Duchenne Dystrophy
● d. Osteogenesis imperfecta

Answer 9

B

Question 10

A glycosaminoglycan that has D-glucuronic acid as a repeating unit which is significant as a lubricant and in vitreous humor consistency:
● a. Heparin
● b. Chondroitin sulfate
● c. Hyaluronic acid
● d. Keratin sulfate

Answer 10

C

Question 11

An important glycosaminoglycan that is significant as anticoagulant:
● a. Chondroitin sulfate
● b. Dermatan sulfate
● c. Heparin
● d. Hyaluronic acid

Answer 11

C

Question 12

The enzyme that catalyzes formation of covalent links between collagen:
● a. N and C- proteinase
● b. Prolyl hydroxylase
● c. Glucosyl transferase
● d. Lysyl oxidase

Answer 12

D

Question 13

The type of collagen present in the basement membrane:
a. I
b. II
c. III
d. IV

Answer 13

D

Question 14

The following statement/s is/are TRUE about collagen:
● a. Constitutes 25% of the protein in mammals
● b. Provides an extracellular framework for all metazoan animals
● c. At least 28 types of collagen made up of over 30 distinct polypeptide chain
● d. All of the above

Answer 14

D

Question 15

What type of collagen constitutes muscle and most connective tissues?
● a. Type IV
● b Type V
● c. Type VI
● d. Type VII

Answer 15

C

Question 16

What type of collagen constitutes non cartilaginous connective tissues, bone, tendon and skin?
● a. Type I
● b. Type Il
● c. Type Ill
● d. Type IV

Answer 16

A

Question 17

Type of collagen seen in cartilage tissues:
● a. Type I
● b. Type lI
● c. Type III
● d. Type IV

Answer 17

B

Question 18

What protein confers rigidity on collagen molecule?
● a. Glycine
● b. Proline
● c. Hydroxyproline
● d. B and C

Answer 18

D

Question 19

Hydroxylation of proline and lysine residues and glycosylation of hydroxylysines in the procollagen molecule take place at this site:
● Mitochondria
● b. Golgi complex
● C. Endoplasmic Reticulum
● d. Nucleus

Answer 19

C

Question 20

It is a large glycoprotein present on cell surfaces, extracellular matrix and blood. It also binds collagen fibers during aggregation and alters the kinetics of fiber formation in the pericellular matrix.
● Fibronectin
● Fibrin
● C. Laminin
● d. Elastin

Answer 20

A

Question 21

A patient came in to your clinic complaining of bleeding gums, subcutaneous… do not heal. These signs reflect defective synthesis of collagen due to redness.
a. prolyl and lysyl hydroxylases
b. prolyl and lysyl oxidase
c. lysyl oxidase
d. proline hydroxylase

Answer 21

A

Question 22

In epidermolysis bullosa, the skin breaks and blisters as a result of the disease due to mutation in
a. COL7A1 (TYPE VII)
b. COL4A3 (TYPE IV)
c. COL3A1 (TYPE III)
d. COL1A1 (TYPE I)

Answer 22

A

Question 23

What role does fibrillin-1 play in the ECM?
A) It is primarily responsible for the hydration of tissues.
B) It provides structural support and regulates the activity of growth factors.
C) It facilitates cell adhesion to the ECM.
D) It is involved in the degradation of collagen.

Answer 23

B) It provides structural support and regulates the activity of growth factors.
Rationale: Fibrillin-1 is essential for the formation of microfibrils that contribute to the structural integrity of the ECM and regulate growth factors like TGF-β.

Question 24

Which of the following is a key diagnostic tool for Marfan syndrome?
A) Genetic testing for FBN1 mutations
B) MRI of the brain
C) Bone density scan
D) Blood glucose levels

Answer 24

A) Genetic testing for FBN1 mutations
Rationale: Genetic testing for mutations in the FBN1 gene is a definitive diagnostic tool for Marfan syndrome

Question 25

In the context of ECM, what is the significance of glycosaminoglycans (GAGs)?
A) They provide tensile strength.
B) They assist in cell signaling.
C) They maintain tissue hydration and elasticity.
D) They help in cell proliferation.

Answer 25

C) They maintain tissue hydration and elasticity.
Rationale: GAGs are polysaccharides that attract water, contributing to the ECM’s ability to maintain hydration and provide resilience.

Question 26

Which imaging modality is most useful for assessing aortic dilation in patients with Marfan syndrome?
A) X-ray
B) MRI
C) CT scan
D) Echocardiography

Answer 26

D) Echocardiography
Rationale: Echocardiography is a key tool in monitoring aortic dimensions in Marfan patients and is widely used due to its non-invasive nature.

Question 27

Which of the following mechanisms best explains the increased risk of aortic dilation and dissection in patients with Marfan syndrome?
A) Increased collagen deposition
B) Defective elastic fiber formation and altered TGF-β signaling
C) Decreased mechanical stress on the aorta
D) Reduced vascular smooth muscle cell proliferation

Answer 27

B) Defective elastic fiber formation and altered TGF-β signaling
Rationale: In Marfan syndrome, mutations in fibrillin-1 lead to abnormal elastic fiber formation and dysregulation of TGF-β signaling, contributing to vascular wall weakness and aortic complications.

Question 28

In assessing the cardiovascular risks associated with Marfan syndrome, which of the following echocardiographic findings would most likely indicate a need for surgical intervention?
A) Aortic root diameter of 3.5 cm
B) Aortic root diameter of 5.0 cm or greater
C) Aortic regurgitation without dilation
D) Mild mitral valve prolapse

Answer 28

B) Aortic root diameter of 5.0 cm or greater
Rationale: Surgical intervention is typically recommended when the aortic root diameter exceeds 5.0 cm due to the high risk of dissection at this size

Question 29

When considering the differential diagnosis of Marfan syndrome, which of the following conditions shares a similar phenotype but is genetically distinct?
A) Ehlers-Danlos syndrome
B) Osteogenesis imperfecta
C) Loeys-Dietz syndrome
D) Achondroplasia

Answer 29

C) Loeys-Dietz syndrome
Rationale: Loeys-Dietz syndrome presents with features similar to Marfan syndrome, such as cardiovascular complications and skeletal features, but is caused by mutations in different genes (e.g., TGFBR1, TGFBR2).

Question 30

What is the role of TGF-β in the pathology of Marfan syndrome, and how does its dysregulation contribute to clinical manifestations?
A) It promotes collagen synthesis, leading to stiffened arterial walls.
B) It increases vascular smooth muscle proliferation, enhancing vessel strength.
C) It mediates inflammation and tissue remodeling, exacerbating aortic dilation.
D) It inhibits elastin formation, causing joint hypermobility.

Answer 30

C) It mediates inflammation and tissue remodeling, exacerbating aortic dilation.
Rationale: Dysregulated TGF-β signaling in Marfan syndrome leads to inappropriate tissue remodeling and inflammation, contributing to the weakening of vascular structures.

Question 31

In the context of Marfan syndrome, how does the clinical manifestation of lens dislocation (ectopia lentis) occur, and what is its genetic basis?
A) Disruption of collagen synthesis leading to weakened zonules
B) Abnormal formation of the cornea due to connective tissue dysplasia
C) Impaired blood supply to the lens capsule from elastic fiber defects
D) Accumulation of hyaluronic acid within the lens fibers

Answer 31

A) Disruption of collagen synthesis leading to weakened zonules
Rationale: Ectopia lentis is caused by weakened zonular fibers, which are composed of fibrillin, due to mutations in the FBN1 gene affecting the structural integrity of the lens