Genetics and Disease Practice Questions

Q: Which of the following is not a major criterion for diagnosing Marfan syndrome?

Striae over the buttocks. Striae over the buttocks - While striae (stretch marks) can be common in individuals with Marfan syndrome due to connective tissue fragility, they are considered a minor criterion rather than a major one based on the Ghent nosology. - Major criteria are defined by their higher diagnostic specificity and clinical significance in identifying Marfan syndrome. Ectopia lentis - Ectopia lentis (dislocation of the ocular lens) is a major diagnostic criterion for Marfan syndrome and is highly specific to the condition. - It results from the weakness of the suspensory ligaments of the lens due to fibrillin-1 deficiency. Dilatation of the ascending aorta - Aortic root dilatation and aortic dissection are critical cardiovascular manifestations and major diagnostic criteria for Marfan syndrome [1]. - These reflect the systemic connective tissue defect affecting the integrity of the aortic wall and are associated with significant morbidity and mortality [1]. Dural ectasia - Dural ectasia, which is the widening of the dural sac due to weakening of connective tissue, is a major criterion for the diagnosis of Marfan syndrome when observed on imaging studies. - It often occurs in the lumbosacral region and can cause neurological symptoms.

Q: Which of the following is a feature of Ehlers-Danlos syndrome?

Joint hypermobility. ***Pectus excavatum*** - This condition is characterized by a **depression of the sternum**, leading to a sunken chest appearance, and is least commonly associated with Ehlers-Danlos syndrome (EDS). - Other forms of EDS may present with more notable **joint hypermobility** and skin elasticity issues, rather than pectus excavatum [1]. *Kyphoscoliosis* - This is a common complication in certain types of Ehlers-Danlos syndrome, particularly affecting the spine's curvature [1]. - It is associated with **joint hypermobility** and can lead to significant postural abnormalities [1]. *Achalasia* - While achalasia can occur in EDS, it is not a typical or common association. - This esophageal motility disorder primarily affects **swallowing** due to a failure of the lower esophageal sphincter to relax. *Dermatosparaxis* - This form of EDS specifically features **skin fragility** and tearing with minimal trauma, indicating a significant association with the syndrome [1]. - It is characterized by **excessively fragile skin** and is directly linked to the pathogenic mechanisms of EDS [1].

Q: What is the most characteristic finding in familial adenomatous polyposis (FAP)?

Autosomal dominant inheritance. ***Familial adenomatous polyposis affects both males and females equally.*** - Familial adenomatous polyposis (FAP) follows an **autosomal dominant inheritance pattern**, therefore affecting both genders. - It typically presents with **hundreds to thousands of adenomatous polyps** in the colon, leading to a significant risk for colon cancer if untreated [1]. *If not treated, it progresses to malignancy in nearly all cases.* - While untreated FAP has a high risk for colorectal cancer, it does not mean **all cases** progress to malignancy; some may be managed effectively. - Regular screening and prophylactic surgery can significantly **reduce** the malignant potential associated with the condition [1]. *Males and females are affected equally.* - While FAP affects males and females, the tendency for development of certain cancers may vary; stating it affects them **equally** could be misleading due to varying cancer risks. - The inheritance and clinical implications do not make a distinction based on gender despite equal prevalence. *Autosomal dominant inheritance.* - This statement about inheritance is indeed **true**, but it is not the correct statement regarding FAP's equality in affecting genders. - The **mutated APC gene** is responsible for FAP, leading to the widespread formation of polyps and the risk of colon cancer [1].

Q: In Kartagener syndrome, the cause of infertility is?

Asthenospermia. ***Asthenospermia*** - In Kartagener syndrome, **dynein arms** in sperm flagella are defective, leading to **poor sperm motility**. - This severely impairs the sperm's ability to reach and fertilize an egg, resulting in **infertility**. *Oligospermia* - This refers to a **low sperm count** and is not the primary cause of infertility in Kartagener syndrome. - While overall semen quality can be affected, the central issue is the **lack of sperm movement**, not insufficient numbers. *Undescended testis* - Also known as **cryptorchidism**, this condition involves one or both testes failing to descend into the scrotum. - It leads to impaired sperm production due to higher intra-abdominal temperatures, but is unrelated to the **ciliary dysfunction** seen in Kartagener syndrome. *Epididymal obstruction* - This involves a blockage in the **epididymis**, preventing sperm from being ejaculated. - While it causes infertility, it is a structural problem and does not account for the **motility defects** seen in Kartagener syndrome.

Question 1

Which of the following is not a major criterion for diagnosing Marfan syndrome?

Accepted Answer

Striae over the buttocks

Answer

Dilatation of the ascending aorta

Answer

Dural ectasia

Answer

Ectopia lentis

Question 2

Which of the following is a feature of Ehlers-Danlos syndrome?

Accepted Answer

Joint hypermobility

Answer

Achalasia

Answer

Kyphoscoliosis

Answer

Dermatosparaxis

Question 3

What is the most characteristic finding in familial adenomatous polyposis (FAP)?

Accepted Answer

Autosomal dominant inheritance

Answer

Predominantly affects males

Answer

If not treated, FAP has a very high risk of progressing to malignancy.

Answer

Males and females are affected equally

Question 4

In Kartagener syndrome, the cause of infertility is?

Accepted Answer

Asthenospermia

Answer

Oligospermia

Answer

Undescended testis

Answer

Epididymal obstruction

Genetics and Disease — MCQs

Genetics and Disease — MCQs

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