Osteogenesis Imperfecta Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Osteogenesis Imperfecta. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Osteogenesis Imperfecta Indian Medical PG Question 1: Blue sclera is seen in all of the following conditions except:
- A. Marfan's syndrome
- B. Osteogenesis imperfecta
- C. Keratoconus (Correct Answer)
- D. Rheumatoid arthritis
Osteogenesis Imperfecta Explanation: ***Keratoconus***
- Keratoconus is a progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape, leading to **vision distortion**.
- Blue sclera is **not a feature** of keratoconus. This is a **corneal condition** that does not affect the sclera.
- Blue sclera, seen in the other conditions listed, occurs due to thinning of the sclera, making the underlying choroidal pigment visible.
*Marfan's syndrome*
- Patients with Marfan's syndrome can have blue sclera due to the **thinning of collagen** in the scleral tissue, allowing the underlying choroid to show through.
- This connective tissue disorder affects multiple body systems, including the skeletal, cardiovascular, and ocular systems, with features like **arachnodactyly** and **aortic root dilation**.
*Osteogenesis imperfecta*
- Often referred to as **brittle bone disease**, osteogenesis imperfecta is characterized by defective **type I collagen synthesis**, which also affects the sclera.
- The sclera becomes thin and translucent, revealing the underlying choroidal pigment, thus appearing **blue**.
*Rheumatoid arthritis*
- In rheumatoid arthritis, particularly with severe or long-standing disease, the sclera can become thinned due to **scleritis** or **scleromalacia perforans**.
- This thinning can lead to a **blue discoloration** of the sclera, making the underlying choroid visible.
Osteogenesis Imperfecta Indian Medical PG Question 2: Which of the following is not typically associated with osteogenesis imperfecta?
- A. Blue sclera
- B. Lax ligament
- C. Bilateral Hip dislocation (Correct Answer)
- D. Osteoporosis
Osteogenesis Imperfecta Explanation: ***Bilateral Hip dislocation***
- While hip dislocations can occur in severe cases due to bone fragility, **bilateral hip dislocation** is not a characteristic or typical primary association with osteogenesis imperfecta.
- The underlying issue is primarily **bone fragility** leading to fractures, not inherent joint instability or malformation causing bilateral dislocation.
*Blue sclera*
- **Blue sclera** is a classic sign of osteogenesis imperfecta, caused by the thinness of the sclera allowing the underlying choroid vessels to show through.
- This is due to a defect in **Type I collagen** synthesis, which affects not only bones but also other connective tissues including the sclera.
*Lax ligament*
- **Lax ligaments** are common in osteogenesis imperfecta due to the generalized **connective tissue defect**, particularly involving Type I collagen.
- This can contribute to joint instability, *hypermobility*, and an increased risk of sprains.
*Osteoporosis*
- **Osteoporosis** with reduced bone mineral density is a hallmark feature of osteogenesis imperfecta, leading to **fragile bones** and recurrent fractures.
- The genetic defect in **Type I collagen** impairs bone matrix formation, resulting in weak and brittle bones.
Osteogenesis Imperfecta Indian Medical PG Question 3: Mutations in type I collagen fibres results in:
- A. Osteogenesis imperfecta (Correct Answer)
- B. Osteosclerosis
- C. Osteopetrosis
- D. Marfan's syndrome
Osteogenesis Imperfecta Explanation: ***Osteogenesis imperfecta***
- This condition is primarily caused by **genetic defects** in the genes encoding **Type I collagen**, particularly *COL1A1* and *COL1A2*.
- It leads to **fragile bones** that fracture easily, **blue sclera**, **hearing loss**, and **dentinogenesis imperfecta**, due to the impaired formation of collagen, a major component of bone and connective tissues.
*Osteosclerosis*
- This refers to a general term for **increased bone density** and hardening of bone, which can be a symptom of various conditions.
- It is not caused by a specific mutation in Type I collagen but rather points to an **imbalance in bone remodeling** where bone formation outpaces resorption.
*Osteopetrosis*
- Also known as **Albers-Schönberg disease** or **marble bone disease**, this condition is characterized by **abnormally dense bones** due to a defect in **osteoclast function**, which impairs bone resorption [1].
- It is primarily caused by mutations in genes involved in osteoclast development and acidification, such as *CLCN7*, not Type I collagen genes [1].
*Marfan's syndrome*
- This is a **connective tissue disorder** caused by a mutation in the *FBN1 gene* encoding **fibrillin-1**, a protein essential for the formation of elastic fibers.
- It affects the **skeleton, eyes, heart, and blood vessels**, leading to features like tall stature, long limbs, and cardiovascular abnormalities, distinct from collagen defects causing bone fragility.
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1188.
Osteogenesis Imperfecta Indian Medical PG Question 4: Not seen in osteogenesis imperfecta
- A. Thick cortical bone (Correct Answer)
- B. Wormian bones
- C. Coxa vara
- D. Saber shin
Osteogenesis Imperfecta Explanation: ***Thick cortical bone***
- Osteogenesis imperfecta (OI) is characterized by **fragile bones** due to defects in **Type I collagen** synthesis, leading to abnormally **thin cortical bone**.
- **Thick cortical bone** would indicate increased bone density or strength, which is the opposite of the fundamental pathology in OI.
*Wormian bones*
- **Wormian bones** (intrasutural bones) are frequently seen in individuals with **osteogenesis imperfecta**, particularly in types I and III.
- They are small, irregular bones that develop within the **cranial sutures**.
*Coxa vara*
- **Coxa vara**, a deformity where the angle between the femoral neck and shaft is decreased, is a common orthopedic complication of **osteogenesis imperfecta**.
- This deformity is primarily due to the **bone fragility** and remodeling issues inherent to the condition.
*Saber shin*
- **Saber shin** refers to an anterior bowing of the tibia, which is a classic orthopedic manifestation in patients with **osteogenesis imperfecta**.
- This bowing results from repeated microfractures and **abnormal bone remodeling** characteristic of the disease.
Osteogenesis Imperfecta Indian Medical PG Question 5: Brittle bone disease is -
- A. Osteoporosis
- B. Pagets disease
- C. Osteopetrosis
- D. Osteogenesis imperfecta (Correct Answer)
Osteogenesis Imperfecta Explanation: ***Osteogenesis imperfecta***
- **Osteogenesis imperfecta** is an inherited disorder characterized by **brittle bones** that fracture easily, due to a defect in **collagen type I** synthesis.
- Patients often present with **blue sclera**, **dentinogenesis imperfecta**, and **hearing loss**, in addition to frequent fractures.
*Osteoporosis*
- **Osteoporosis** is a condition of **decreased bone density**, making bones fragile and prone to fracture, but it is not typically referred to as "brittle bone disease" in the same congenital sense.
- It is more common in older adults and is often related to **hormonal changes** (e.g., post-menopause) or lifestyle factors.
*Paget's disease*
- **Paget's disease of bone** involves abnormal bone remodeling with excessive bone resorption followed by disorganized and expanded bone formation, leading to **enlarged, weakened bones**.
- It typically affects older individuals and can lead to bone pain, deformities, and fractures, but it's not the primary condition associated with "brittle bone disease."
*Osteopetrosis*
- **Osteopetrosis** is characterized by **abnormally dense bones** due to impaired osteoclast function, leading to a buildup of bone.
- While bones are dense, they are also **brittle** and prone to fracture, and the condition is also known as "marble bone disease" rather than "brittle bone disease."
Osteogenesis Imperfecta Indian Medical PG Question 6: Which of the following is not a differential diagnosis of non-accidental injury?
- A. Osteogenesis imperfecta
- B. Scurvy
- C. Caffey's disease
- D. Osteopetrosis (Correct Answer)
Osteogenesis Imperfecta Explanation: ***Correct: Osteopetrosis***
- Osteopetrosis is a rare genetic disorder characterized by **increased bone density** due to defective osteoclast function
- While it causes bones to be brittle and prone to fracture, it has **distinctive radiological features** including diffuse sclerosis and "bone-within-bone" appearance
- The **increased bone density on X-ray** is pathognomonic and readily distinguishes it from NAI, making it **less likely to be confused** with non-accidental injury in clinical practice
- Fractures occur but the radiological pattern is diagnostic of the underlying metabolic bone disease
*Incorrect: Osteogenesis imperfecta*
- This is a **classic differential** for NAI causing **multiple brittle bone fractures** that can be mistaken for abuse
- Features include **blue sclera**, **dentinogenesis imperfecta**, **wormian bones**, and **family history**
- Often presents with multiple fractures at different stages of healing, mimicking the pattern seen in NAI
*Incorrect: Scurvy*
- Caused by **vitamin C deficiency**, leads to defective collagen synthesis
- Results in **subperiosteal hemorrhages**, **metaphyseal fractures**, and **periosteal elevation** that closely mimic NAI
- Additional features include **gingival bleeding**, **petechiae**, **follicular hyperkeratosis**, and **poor wound healing**
*Incorrect: Caffey's disease*
- Also known as **infantile cortical hyperostosis**, presents in infants under 6 months
- Causes **periosteal reactions**, **bone thickening**, and **soft tissue swelling** in long bones, ribs, and mandible
- The periosteal new bone formation can be mistaken for healing fractures from NAI, making it an important differential
Osteogenesis Imperfecta Indian Medical PG Question 7: Select the type of bone disease which is most likely to be associated with genetically determined disorder in the structure or processing of type I collagen (SELECT 1 DISEASE)
- A. Osteogenesis imperfecta (Correct Answer)
- B. Osteopetrosis
- C. Osteomalacia
- D. Osteitis fibrosa cystica
Osteogenesis Imperfecta Explanation: ***Osteogenesis imperfecta***
- This condition is primarily caused by **genetic defects** in the production of **type I collagen**, leading to fragile bones.
- Due to these defects, bones are prone to **fractures** with minimal trauma.
*Osteopetrosis*
- Characterized by abnormally **dense bones** due to a defect in **osteoclast function**, not collagen structure [1].
- This leads to bones that are brittle and prone to fracture, but the underlying cause is different from collagen abnormalities [1].
*Osteomalacia*
- This refers to the **softening of bones** due to impaired **mineralization**, most commonly from **vitamin D deficiency** or phosphate imbalance.
- It does not involve a primary defect in the genetic structure or processing of type I collagen.
*Osteitis fibrosa cystica*
- This is a bone lesion caused by **severe hyperparathyroidism**, leading to excessive bone resorption and replacement by fibrous tissue and cysts.
- It is an endocrine disorder affecting **calcium metabolism**, not a primary collagenopathy.
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1188.
Osteogenesis Imperfecta Indian Medical PG Question 8: A 10-year-old girl presents with severe joint laxity, scoliosis, and a history of easy bruising. Which of the following conditions is most likely?
- A. Ehlers-Danlos syndrome (Correct Answer)
- B. Marfan's syndrome
- C. Rheumatoid arthritis
- D. Osteogenesis imperfecta
Osteogenesis Imperfecta Explanation: ***Ehlers-Danlos syndrome***
- This syndrome is characterized by defects in **collagen synthesis** and structure, leading to **joint hypermobility** (laxity) [1], skin hyperextensibility, and fragility, which explains the easy bruising [1].
- **Scoliosis** is a common musculoskeletal manifestation due to weakened connective tissue support [1].
*Marfan's syndrome*
- While Marfan's syndrome also presents with **joint laxity** and **scoliosis**, its defining features include distinct skeletal abnormalities (e.g., **arachnodactyly**, sternal deformities) and **cardiovascular abnormalities** (e.g., aortic root dilatation), which are not mentioned here.
- **Easy bruising** is not a prominent feature of Marfan's syndrome.
*Rheumatoid arthritis*
- This is an **autoimmune inflammatory arthritis** primarily affecting synovial joints, causing pain, swelling, and stiffness, often symmetrically.
- It does not typically present with severe **joint laxity** throughout the body, **scoliosis**, or **easy bruising** as primary features in a 10-year-old.
*Osteogenesis imperfecta*
- This condition is characterized by **brittle bones** due to defective collagen, leading to recurrent **fractures** with minimal trauma.
- While patients can have some **joint laxity** and **scoliosis**, the most prominent symptom is bone fragility, often accompanied by **blue sclerae**, which is not mentioned, and easy bruising is less indicative than in EDS.
Osteogenesis Imperfecta Indian Medical PG Question 9: Osteogenesis imperfecta is due to a defect in what?
- A. Type II collagen
- B. Type IV collagen
- C. Type I collagen (Correct Answer)
- D. Type III collagen
Osteogenesis Imperfecta Explanation: ***Collagen 1***
- Osteogenesis imperfecta is primarily caused by a defect in **type I collagen** [2], which is crucial for bone strength and structure.
- This defect leads to **brittle bones**, resulting in frequent fractures and skeletal deformities .
*Collagen 2*
- Type II collagen is mainly found in **cartilage** and is critical for **hyaline cartilage formation**, not directly involved in bone integrity.
- Defects in type II collagen are associated with conditions like **chondrodysplasia**, rather than osteogenesis imperfecta.
*Collagen 4*
- Type IV collagen is primarily found in **basement membranes** and plays a role in filtration and structural integrity of tissues.
- While important for kidney and eye function, it is not related to the bone fragility seen in osteogenesis imperfecta.
*Collagen 3*
- Type III collagen is involved in the structure of **reticular fibers** and is crucial for skin and blood vessel integrity.
- It is not the primary collagen affected in osteogenesis imperfecta, which is associated specifically with type I collagen defects.
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1182.
[2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1188.
Osteogenesis Imperfecta Indian Medical PG Question 10: An intrauterine scan at the 13th week of pregnancy showed a fetus with multiple long bone fractures. What is commonly associated with this finding?
- A. Osteogenesis imperfecta (Correct Answer)
- B. Marfan syndrome
- C. Achondroplasia
- D. Cretinism
Osteogenesis Imperfecta Explanation: ***Osteogenesis imperfecta***
- **Multiple long bone fractures** detected early in pregnancy are a classic presentation of **osteogenesis imperfecta (OI)**, a genetic disorder characterized by **bone fragility**.
- OI is primarily caused by mutations in genes encoding **type I collagen**, leading to defective bone formation.
*Achondroplasia*
- This condition is a form of **dwarfism** characterized by disproportionately short limbs and a normal-sized trunk, resulting from a mutation in the **FGFR3 gene**.
- While it affects bone growth, it typically does not cause **multiple fractures** prenatally.
*Marfan syndrome*
- This is a connective tissue disorder affecting the skeletal, ocular, and cardiovascular systems, characterized by **tall stature**, **long limbs and fingers**, and **aortic root dilation**.
- It results from a mutation in the **fibrillin-1 gene** and is not primarily associated with prenatal long bone fractures.
*Cretinism*
- This is a historical term for **congenital hypothyroidism**, which results from severely deficient thyroid hormone production in a newborn.
- It leads to developmental delays, growth retardation, and intellectual disability, but not to **multiple bone fractures**.
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