Osteogenesis Imperfecta — MCQs
Blue sclera is seen in all of the following conditions except:
Which of the following is not typically associated with osteogenesis imperfecta?
Mutations in type I collagen fibres results in:
Not seen in osteogenesis imperfecta
Brittle bone disease is -
Which of the following is not a differential diagnosis of non-accidental injury?
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 10-year-old girl presents with severe joint laxity, scoliosis, and a history of easy bruising. Which of the following conditions is most likely?
Osteogenesis imperfecta is due to a defect in what?
An intrauterine scan at the 13th week of pregnancy showed a fetus with multiple long bone fractures. What is commonly associated with this finding?
Osteogenesis Imperfecta Indian Medical PG Practice Questions and MCQs
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
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.
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
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.
Question 3: Mutations in type I collagen fibres results in:
- A. Osteogenesis imperfecta (Correct Answer)
- B. Osteosclerosis
- C. Osteopetrosis
- D. Marfan's syndrome
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.
Question 4: Not seen in osteogenesis imperfecta
- A. Thick cortical bone (Correct Answer)
- B. Wormian bones
- C. Coxa vara
- D. Saber shin
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.
Question 5: Brittle bone disease is -
- A. Osteoporosis
- B. Pagets disease
- C. Osteopetrosis
- D. Osteogenesis imperfecta (Correct Answer)
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."
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)
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
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
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.
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
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.
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
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.
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
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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