Genetics and Disease Practice Questions

Q: All are correct about this patient except:

Eye globe rupture. ***Eye globe rupture*** - Eye globe rupture is **not typically a feature** of Marfan syndrome or Ehlers-Danlos syndrome. - While ocular issues like **ectopia lentis** are common, the globe itself is generally not prone to spontaneous rupture. *Rubber person* - The image shows a person with **hyperextensible skin** and **hyperlax joints**, classical features of **Ehlers-Danlos syndrome**, sometimes referred to colloquially as "rubber person" due to extreme flexibility. - This term describes the characteristic **skin elasticity and joint hypermobility** seen in certain collagen disorders. *Ectopia lentis* - Ectopia lentis, or **dislocation of the lens**, is a common and characteristic ocular manifestation of **Marfan syndrome**. - It results from defective **fibrillin-1**, which is a key component of the suspensory ligaments of the lens. *Aortic rupture* - **Aortic dilation** and **aneurysm** leading to rupture or dissection are serious and potentially fatal complications of **Marfan syndrome**. - This is due to weakened connective tissue in the aortic wall, caused by the **fibrillin-1 defect**.

Q: Which of the following will not be the feature of this patient shown below who has urine nitroprusside test positive? (Recent NEET Pattern 2016-17)

Normal IQ. ***Normal IQ*** - Homocystinuria, characterized by a positive urine nitroprusside test and Marfanoid features, typically presents with **intellectual disability** (low IQ), ranging from mild to severe. - Therefore, a normal IQ would not be a feature of this patient. *Marfanoid habitus* - The patient's tall, slender build with long limbs and **scoliosis** (evident in the image by the stooped posture and uneven shoulders) is consistent with a **Marfanoid habitus**, a common feature of homocystinuria. - This is due to disturbances in connective tissue metabolism, affecting skeletal development. *Prothrombotic state* - Homocystinuria leads to elevated levels of homocysteine, which is highly **toxic to endothelial cells** and promotes abnormal blood clot formation. - This results in a **prothrombotic state**, increasing the risk of both venous and arterial thromboses. *Arachnodactyly* - The patient exhibits features of **arachnodactyly**, characterized by **long, slender fingers and toes**, which is a classic skeletal manifestation of homocystinuria. - This finding is consistent with the connective tissue abnormalities seen in the condition.

Q: A patient presents with headache, confusion, and a diagnosis of a brain tumor. The family history reveals brain and kidney tumors. What is the most likely diagnosis?

VHL syndrome. ***VHL syndrome*** - **Von Hippel-Lindau (VHL) syndrome** is an inherited disorder characterized by the growth of tumors and cysts in various parts of the body, including the **brain (hemangioblastomas)** and **kidneys (renal cell carcinoma)**. - The presentation of a brain tumor, kidney tumors, and a positive family history for both organs strongly points to VHL syndrome. *Neurofibromatosis* - **Neurofibromatosis (NF)** typically presents with **cafe-au-lait spots**, neurofibromas, optic gliomas, and Lisch nodules. - While it involves brain tumors, kidney tumors are not a primary feature of NF. *Li-Fraumeni syndrome* - **Li-Fraumeni syndrome** is associated with an increased risk of various cancers, including **sarcomas**, **breast cancer**, **adrenocortical carcinomas**, and **leukemia**. - While brain tumors can occur, the specific combination of brain and kidney tumors with a clear family history is less characteristic of Li-Fraumeni than VHL syndrome. *Churg-Strauss syndrome* - **Churg-Strauss syndrome (Eosinophilic Granulomatosis with Polyangiitis)** is a systemic vasculitis characterized by **asthma**, **eosinophilia**, and **granulomatous inflammation**. - It does not involve the development of brain or kidney tumors.

Q: Seminal vesicles and vas deferens would be bilaterally absent congenitally in which of the following conditions?

Cystic fibrosis. ***Cystic fibrosis*** - **Congenital bilateral absence of the vas deferens (CBAVD)** is found in over 95% of males with cystic fibrosis, often leading to infertility. - This condition results from mutations in the **CFTR gene**, which is responsible for chloride transport, causing thick, viscous secretions that block or prevent the development of these structures. *Kartagener syndrome* - This syndrome is a subgroup of **primary ciliary dyskinesia**, characterized by a triad of *situs inversus*, chronic sinusitis, and bronchiectasis. - While it causes **infertility due to immotile sperm**, the male reproductive tract organs like the vas deferens and seminal vesicles are typically present. *Klinefelter syndrome* - Individuals with Klinefelter syndrome have a **47,XXY karyotype** and typically present with small testes, azoospermia, and hypogonadism [1]. - However, the **vas deferens and seminal vesicles are usually present**, though they may be underdeveloped or dysfunctional. *Kallmann syndrome* - This is a form of **hypogonadotropic hypogonadism** associated with anosmia or hyposmia (impaired sense of smell). - It results from a failure of GnRH-producing neurons to migrate to the hypothalamus, affecting hormone production, but the **anatomical structures of the vas deferens and seminal vesicles are usually intact**.

Q: Which of the following statements are true about familial adenomatous polyposis? 1. It is autosomal recessive 2. If not treated, 100% of the cases progress to adenocarcinoma colon. 3. It is associated with a gene mutation in KRAS 4. It is associated with congenital hypertrophy of the retinal pigment epithelium.

2 and 4. ***2 and 4*** - Without treatment, **familial adenomatous polyposis (FAP)** leads to colorectal **adenocarcinoma** in 100% of cases, due to the accumulation of numerous adenomatous polyps throughout the colon. - FAP is strongly associated with **congenital hypertrophy of the retinal pigment epithelium (CHRPE)**, which can be an early diagnostic marker [1]. *None of the options* - This statement is incorrect because FAP does indeed involve the progression to adenocarcinoma and is associated with CHRPE. - The combination of these two true statements makes this option invalid. *1 and 4* - FAP is inherited in an **autosomal dominant** manner, not autosomal recessive [1]. - While statement 4 (association with CHRPE) is true, statement 1 being false makes this option incorrect. *2 and 3* - Although statement 2 (100% progression to adenocarcinoma) is true, statement 3 is incorrect. - FAP is primarily caused by mutations in the **APC gene**, not the KRAS gene [1]. KRAS is more commonly associated with sporadic colorectal cancer progression rather than FAP.

Q: A karyotyping image is given below. What are the clinical features most likely to be expected in such patients?

Gynecomastia and long limbs. ***Gynecomastia and long limbs*** - The given karyotype shows **47, XXY**, which is characteristic of **Klinefelter syndrome**. - **Gynecomastia** and **long limbs** (tall stature with disproportionately long legs and arms) are classic features of Klinefelter syndrome due to the extra X chromosome's effect on hormonal balance and growth. *Flat occiput* - A **flat occiput** is a characteristic feature of **Down syndrome (Trisomy 21)**, not Klinefelter syndrome. - Down syndrome also presents with other distinct features such as epicanthic folds, a single palmar crease, and intellectual disability. *Webbing of neck and lymphedema* - **Webbing of the neck** and **lymphedema** (especially of the hands and feet) are prominent features of **Turner syndrome (45, X0)**. - Turner syndrome is a sex chromosome aneuploidy affecting females, characterized by short stature, ovarian dysgenesis, and often congenital heart defects like coarctation of the aorta. *Short stature and polydactyly* - While **short stature** can be associated with various genetic conditions (e.g., Turner syndrome, achondroplasia), it is generally **not a primary feature of Klinefelter syndrome**, which typically involves tall stature. - **Polydactyly** (extra fingers or toes) is a feature of several genetic syndromes, such as Patau syndrome (Trisomy 13) or Bardet-Biedl syndrome, and is not associated with Klinefelter syndrome.

Q: Which pattern of inheritance of disease is associated with consanguinity?

Autosomal recessive. ***Autosomal recessive*** - Consanguineous relationships increase the likelihood of offspring inheriting **two copies of a rare deleterious recessive allele**, one from each parent [1]. - This occurs because relatives share a greater proportion of their genes, making it more probable that both parents are **heterozygous carriers** for the same recessive disorder. *Autosomal dominant* - In autosomal dominant disorders, only **one copy of the altered gene** is needed to cause the disease, so expression is not typically influenced by consanguinity. - These conditions often manifest in every generation and are not more prevalent with increased shared genetic material. *X-linked recessive* - X-linked recessive disorders primarily affect males, as they only have one X chromosome, and are transmitted by carrier females. - While consanguinity can theoretically increase the carrier rate within a population, its direct impact on the inheritance pattern of an X-linked trait in a single family is less pronounced compared to autosomal recessive conditions. *X-linked dominant* - X-linked dominant disorders are expressed in heterozygous females and hemizygous males, with affected males often having more severe disease. - The inheritance pattern is not significantly influenced by consanguinity, as only one copy of the affected gene on the X chromosome is sufficient for disease manifestation.

Q: Which of the following provide protection against malaria except

PNH. ***PNH*** - **Paroxysmal nocturnal hemoglobinuria (PNH)** is a rare, acquired clonal disorder of hematopoietic stem cells characterized by complement-mediated hemolysis. - It does not offer any known protective advantage against malaria infection; in fact, chronic hemolysis could potentially complicate malaria diagnosis or management. *Thalassemia* - Individuals with **thalassemia traits (heterozygotes)**, particularly alpha-thalassemia, have red blood cells that are more resistant to malarial parasite invasion and growth [1]. - This protection is thought to arise from altered red cell morphology, reduced parasite multiplication, and enhanced clearance of infected cells. *Sickle cell anemia* - The **heterozygous state (sickle cell trait)** provides significant protection against severe malaria, as the altered hemoglobin S in red blood cells inhibits parasite growth and promotes early clearance of infected cells [1], [2]. - Although the homozygous state (sickle cell anemia) can be severe, even carriers benefit from reduced malaria susceptibility. *Duffy blood group* - Absence of the **Duffy antigen on red blood cells**, common in West African populations, provides complete protection against infection with **Plasmodium vivax** malaria. - The Duffy antigen receptor is essential for *P. vivax* to invade human red blood cells.

Q: Syndrome which is characterized by 2X chromosomes and 1Y chromosome is:

Klinefelter syndrome. ***Klinefelter syndrome*** - This syndrome is characterized by a **47, XXY karyotype**, meaning individuals have **two X chromosomes** and one Y chromosome [1]. - It affects males, leading to features such as **small testes**, **infertility**, gynecomastia, and often taller stature [1], [3]. *Turner syndrome* - This syndrome is characterized by a **45, X karyotype**, meaning individuals have only **one X chromosome** and no second sex chromosome [2]. - It affects females, leading to features like **short stature**, a **webbed neck**, and ovarian dysgenesis [2]. *Marfan syndrome* - This is an **autosomal dominant genetic disorder** affecting connective tissue, caused by mutations in the **FBN1 gene**. - It is characterized by **tall stature**, long limbs (arachnodactyly), **cardiovascular abnormalities** (e.g., aortic dissection), and ocular problems (e.g., lens dislocation). *Down syndrome* - This syndrome is caused by **trisomy 21**, meaning individuals have an **extra copy of chromosome 21**. - It is characterized by specific **facial features**, intellectual disability, and an increased risk of certain medical conditions like congenital heart defects.

Q: Malaria protection comes from all Except

Acanthocytosis. ***Acanthocytosis*** - **Acanthocytosis** is characterized by abnormal, spiky red blood cells due to lipid membrane defects and does **not** provide protection against malaria. - While red blood cell abnormalities can sometimes offer malaria resistance, acanthocytosis is not one of these known protective conditions. *Sickle cell anemia* - Individuals with **sickle cell trait (heterozygous)** have red blood cells that are less hospitable to the *Plasmodium falciparum* parasite, providing **significant protection** against severe malaria [2]. - The abnormal hemoglobin in sickle cells can lead to premature destruction of infected red blood cells or inhibit parasite growth. *Thalassemia* - **Thalassemia syndromes**, particularly alpha and beta thalassemia traits, provide a degree of protection against malaria [2]. - The affected red blood cells are less suitable for parasite multiplication, and immune responses may be modulated. *G6PD deficiency* - Individuals with **G6PD deficiency** have red blood cells that are more susceptible to oxidative stress, which can inhibit the growth of malaria parasites [1]. - This deficiency causes premature destruction of infected red blood cells, thereby limiting parasite load and providing **some protection** against severe malaria [1].

Question 1

All are correct about this patient except:

Accepted Answer

Eye globe rupture

Answer

Rubber person

Answer

Ectopia lentis

Answer

Aortic rupture

Question 2

Which of the following will not be the feature of this patient shown below who has urine nitroprusside test positive? (Recent NEET Pattern 2016-17)

Accepted Answer

Normal IQ

Answer

Marfanoid habitus

Answer

Prothrombotic state

Answer

Arachnodactyly

Question 3

A patient presents with headache, confusion, and a diagnosis of a brain tumor. The family history reveals brain and kidney tumors. What is the most likely diagnosis?

Accepted Answer

VHL syndrome

Answer

Neurofibromatosis

Answer

Li-Fraumeni syndrome

Answer

Churg-Strauss syndrome

Question 4

Seminal vesicles and vas deferens would be bilaterally absent congenitally in which of the following conditions?

Accepted Answer

Cystic fibrosis

Answer

Kartagener syndrome

Answer

Klinefelter syndrome

Answer

Kallmann syndrome

Question 5

Which of the following statements are true about familial adenomatous polyposis?

1. It is autosomal recessive
2. If not treated, 100% of the cases progress to adenocarcinoma colon.
3. It is associated with a gene mutation in KRAS
4. It is associated with congenital hypertrophy of the retinal pigment epithelium.

Accepted Answer

2 and 4

Answer

None of the options

Answer

1 and 4

Answer

2 and 3

Question 6

A karyotyping image is given below. What are the clinical features most likely to be expected in such patients?

Accepted Answer

Gynecomastia and long limbs

Answer

Flat occiput

Answer

Webbing of neck and lymphedema

Answer

Short stature and polydactyly

Question 7

Which pattern of inheritance of disease is associated with consanguinity?

Accepted Answer

Autosomal recessive

Answer

Autosomal dominant

Answer

X linked recessive

Answer

X linked dominant

Question 8

Which of the following provide protection against malaria except

Accepted Answer

PNH

Answer

Thalassemia

Answer

Sickle cell anemia

Answer

Duffy blood group

Question 9

Syndrome which is characterized by 2X chromosomes and 1Y chromosome is:

Accepted Answer

Klinefelter syndrome

Answer

Turner syndrome

Answer

Marfan syndrome

Answer

Down syndrome

Question 10

Malaria protection comes from all Except

Accepted Answer

Acanthocytosis

Answer

Sickle cell anemia

Answer

Thalassemia

Answer

G6PD deficiency

Genetics and Disease — MCQs

Genetics and Disease — MCQs

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