Block 7 Skin Genomic Imprinting MCQ's
.
Questions and Answers
- 1.
What structure connects the cell to the underlying extracellular matrix?
- A.
Hernidesmosorne
- B.
Desmosome
- C.
Gap junction
- D.
Paciniar corpuscle
- E.
Merckel Corpuscles
- F.
Meissner corpuscles
Correct Answer
A. Hernidesmosorne -
- 2.
A 34-year-old woman is prescribed a topical medication to treat a dermatological condition. Which of the followings statements concerning this medication and its clinical use is most likely correct?
- A.
The drug vehicle exerts minimal influence on the absorption of this medication
- B.
Application of the drug creates a concentration gradient in the patient's skin
- C.
The topical agent is applied four times daily to the affected area
- D.
The possibility of this drug undergoing extensive metabolism in the skin is very low
- E.
The drug possesses a molecular mass of 1600 Da
Correct Answer
B. Application of the drug creates a concentration gradient in the patient's skinExplanation
When a topical medication is applied to the skin, it creates a concentration gradient, meaning that the concentration of the medication is higher at the site of application and gradually decreases as it diffuses into the skin. This allows for the medication to be absorbed into the skin and exert its therapeutic effects. The other statements do not provide information about the mechanism of action or clinical use of the medication.Rate this question:
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- 3.
A 19 year old man has facial and upper back lesions that have waxed and waned for the past 6 years. On examination the lesions have a grayish white plug in the central region. Both his parents had the same lesion at this age. The lesions worsen when he visits his aunt in Arizona. Which of the following organisms is most likely to be a part of the pathogenesis?
- A.
Staphylococcus aureus
- B.
Herpes simplex virus type 1
- C.
Group A Streptocci
- D.
Mycob3cter-furn teprae
- E.
Propionibacteilum acnes
Correct Answer
E. Propionibacteilum acnesExplanation
Propionibacterium acnes is the most likely organism involved in the pathogenesis of the facial and upper back lesions in this 19-year-old man. The presence of a grayish white plug in the central region of the lesions suggests the formation of comedones, which are a characteristic feature of acne. Acne vulgaris is a common skin condition that typically begins in adolescence and is caused by the overgrowth of Propionibacterium acnes in the hair follicles. The fact that both of his parents had similar lesions at the same age suggests a genetic predisposition to acne. The worsening of the lesions in Arizona may be due to environmental factors such as increased humidity or exposure to certain allergens.Rate this question:
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- 4.
In the drawing below, pick the cell (A, B, C, D, or E) that would be actively engaged in secreting lamellar bodies to waterproof the skin
- A.
A
- B.
B
- C.
C
- D.
D
- E.
E
Correct Answer
E. EExplanation
Cell E would be actively engaged in secreting lamellar bodies to waterproof the skin. Lamellar bodies are secreted by the granular cells of the epidermis, which are located in the stratum granulosum layer. In the given drawing, cell E is the only one located in the stratum granulosum layer, making it the correct answer.Rate this question:
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- 5.
Which of the cell types below is directly responsible for the formation of a keloid?
- A.
Cell type A
- B.
Cell type B
- C.
Cell type C
- D.
Cell type D
- E.
None of the above
Correct Answer
E. None of the aboveExplanation
A keloid is an abnormal growth of scar tissue that forms at the site of an injury or incision. It is caused by an overproduction of collagen, a protein that helps in wound healing. While various cell types are involved in wound healing, none of the cell types mentioned in the options are directly responsible for the formation of a keloid. Keloids are primarily formed due to an imbalance in the production and breakdown of collagen, which can be influenced by factors such as genetics, inflammation, and tension on the wound site.Rate this question:
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- 6.
A 28-year-old man reports to his family practitioner complaining of intense itching and the emergence of a pimple-like rash up and down the length cf his arms and legs. The patient reveals that he returned to the United States one week ago after participating in medical mission work in a poor area of a Latin American country. Laboratory investigations of a skin scraping from the patient reveal the presence of Sarcoptes scabiei. The physician prescribes a topical medication that works by disrupting the sodium channel current of the target organism's neurons leading to its paralysis, which of the following agents was prescribed for the patient?
- A.
Iverrnectin
- B.
Lindane
- C.
Doxepin
- D.
Permethrin
- E.
Bexarotene
Correct Answer
D. PermethrinExplanation
Permethrin was prescribed for the patient. Permethrin is a topical medication that works by disrupting the sodium channel current of the target organism's neurons, leading to its paralysis. In this case, the patient has been diagnosed with scabies caused by Sarcoptes scabiei, and Permethrin is an effective treatment for scabies.Rate this question:
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- 7.
SKIN Which of the following structures in the skin is the LEAST likely to be damaged by a second-degree burn?
- A.
Dermal papellae
- B.
Meissner's corpuscles
- C.
Langerhan's cells
- D.
Pacnian corpuscles
- E.
Merkel cells
Correct Answer
D. Pacnian corpusclesExplanation
Pacnian corpuscles are located deep in the dermis and are responsible for detecting deep pressure and vibration. Second-degree burns primarily affect the epidermis and the upper layers of the dermis. Since Pacnian corpuscles are located deeper in the skin, they are less likely to be damaged by a second-degree burn compared to the other structures listed.Rate this question:
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- 8.
Which one of the following describes the secretory mechanism by which sebum ls produced?
- A.
Apocrine
- B.
Merocrine
- C.
Eccrine
- D.
Holocrine
- E.
Paracrine
Correct Answer
D. HolocrineExplanation
Holocrine is the correct answer because it describes the secretory mechanism by which sebum is produced. In the holocrine mechanism, the entire secretory cell becomes filled with sebum and then bursts, releasing the sebum along with cell debris. This is in contrast to other mechanisms such as apocrine, merocrine, eccrine, and paracrine, which do not specifically describe the production of sebum.Rate this question:
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- 9.
You accidentally press your arm against a hot iron, and receive a second-degree burn on a patch of skin. Which of the following cell types is most likely to be killed by this burn?
- A.
Cells within the Meissner's corpuscle
- B.
Cells within the hair root matrix
- C.
Fat cells in the hypodermis
- D.
Keratinacytes of the stratum corneum
- E.
Smooth muscle cells of the arrector pilli muscle
Correct Answer
A. Cells within the Meissner's corpuscleExplanation
The Meissner's corpuscle is a specialized sensory receptor located in the skin that is responsible for detecting light touch and vibration. Second-degree burns involve damage to the epidermis and dermis layers of the skin. Since the Meissner's corpuscle is located within the dermis, it is likely to be affected by the burn and may be killed as a result.Rate this question:
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- 10.
Cytogenetic analysis revealed that a female with Prader Willi syndrome had no visible deletion on chromosome 15q. An alternative explanation of the syndrome in this female IS
- A.
Heterozygosity for the paternal chromosome 15
- B.
Trisomy for chromosome 15
- C.
Isodisomy of the paternal chromosome 15
- D.
Uniparental disomy of the maternal chromosome 15
Correct Answer
D. Uniparental disomy of the maternal chromosome 15Explanation
In Prader Willi syndrome, there is typically a deletion or loss of genetic material on the paternal chromosome 15. However, in this case, the cytogenetic analysis revealed no visible deletion on chromosome 15q. Therefore, an alternative explanation for the syndrome in this female could be uniparental disomy of the maternal chromosome 15, where both copies of the chromosome are inherited from the mother instead of one from each parent.Rate this question:
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- 11.
Neurofibrornatosis type 1 (NF1) is inherited as an autosomal dominant condition. The cardinal features are cafe au lait spots, small soft fleshy growth known as neurofibromata and Lisch nodules in the iris. NF1 is caused by mutations of a gene termed neurofibromin located on chromosome 17. Loss of heterozygosity for markers for chromosome 17 markers has been observed in small benign neurofibromata. This feature is an indication that:
- A.
The gene responsible is likely to be a fibroblast growth factor receptor
- B.
The gene responsible is likely to be an oncogene
- C.
The gene responsible is showing recessive inheritance at cellular level
- D.
A balanced translocation involving an oncogene on chromosome 17 has occurred
- E.
Gene amplification of an oncogene is responsible for the presence of fibromata
Correct Answer
C. The gene responsible is showing recessive inheritance at cellular levelExplanation
Loss of heterozygosity for markers on chromosome 17 in small benign neurofibromata suggests that the gene responsible is showing recessive inheritance at the cellular level. This means that both copies of the gene need to be mutated in order for the disease to manifest. In this case, the loss of one copy of the gene on chromosome 17 leads to the development of neurofibromata.Rate this question:
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- 12.
Martha is 31 she comes to a genetic clinic from a referral from her family physician. The history below reveals several individuals with colon cancer on the side of her mother. Martha's mother died in an accident at the age of 38 and was known to be healthy. Martha explains that she is fine and she has been diagnosed with any health problem and she considers herself unlikely to be at risk of any problem. What is the most appropriate statement that the physician will provide to Martha?
- A.
The high frequency of colon cancer suggests that her maternal grandfather (II-1) is a carrier of a recessive trait
- B.
Because her mother and uncles were not affected it is unlikely that she develop colon cancer
- C.
Martha should only have a colonoscopy only when she reaches the age of 50
- D.
Her 60-year old maternal uncle (III-4) should have a colonoscopy
- E.
Her mother likely was a carrier of this trait, but her father III-1 likely was not a carrier and thus her siblings are unaffected
Correct Answer
D. Her 60-year old maternal uncle (III-4) should have a colonoscopyExplanation
Based on the history provided, Martha's mother died in an accident at the age of 38 and was known to be healthy. However, there is a high frequency of colon cancer on the side of her mother. Therefore, it is important to consider the possibility of a genetic trait or predisposition to colon cancer in Martha's family. The most appropriate statement that the physician will provide to Martha is that her 60-year old maternal uncle (III-4) should have a colonoscopy. This is because her uncle is at an age where screening for colon cancer is recommended, and it can help determine if there is a genetic risk that Martha should be aware of.Rate this question:
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- 13.
Prader-Willi syndrome results from different molecular mechanisms. You have a patient that you suspect has this disorder and you send blood samples on the patient and both parents to the lab for genotyping using a DNA polymorphic marker located close to the centrorneric region on chromosome 15. The following genotypes are found. What is the most likely interpretation of this result? (F=-- father; P= patient; M= Mother)
- A.
A new mutation in the gametes contributed by the father
- B.
Paternal deletion
- C.
Laboratory error
- D.
Non paternity
- E.
Maternal uniparentaidisomy
Correct Answer
E. Maternal uniparentaidisomyExplanation
The most likely interpretation of the given genotypes is maternal uniparental disomy. This means that the patient has inherited two copies of chromosome 15 from the mother and none from the father. This can occur when both copies of chromosome 15 from the father are lost or when there is a duplication of the mother's chromosome 15. This can result in Prader-Willi syndrome, as the genes on the paternal chromosome 15 are usually responsible for preventing the symptoms of the disorder.Rate this question:
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- 14.
The best statement for genomic imprinting is:
- A.
An irreversible process transmitted through successive generations
- B.
Marking of alleles within specific chromosomal regions during male and female gametagenesis
- C.
Occurs mainly on chromosome 15 for humans.
- D.
Occurs mainly during male gametogenesis
- E.
Is known to involve DNA glycosylation
Correct Answer
B. Marking of alleles within specific chromosomal regions during male and female gametagenesisExplanation
Genomic imprinting is a genetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner. It is an inheritance process independent of the classical Mendelian inheritance. Imprinted alleles are silenced such that the genes are either expressed only from the non-imprinted allele inherited from the mother (e.g. H19 or CDKN1C), or in other instances from the non-imprinted allele inherited from the father (e.g. IGF-2). Forms of genomic imprinting have been demonstrated in insects, mammals and flowering plants.
Genomic imprinting is an epigenetic process that involves methylation and histone modifications in order to achieve monoallelic gene expression without altering the genetic sequence. These epigenetic marks are established in the germline and are maintained throughout all somatic cells of an organism.
Appropriate expression of imprinted genes is important for normal development, with numerous genetic diseases associated with imprinting defects including Beckwith–Wiedemann syndrome, Silver–Russell syndrome, Angelman syndrome and Prader–Willi syndrome.Rate this question:
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- 15.
How could the following pedigrees be explained by genetic imprinting?
- A.
Maternal uniparental disomy (UPD)
- B.
Paternal uniparental disomy (UPD)
- C.
Paternal expressed gene
- D.
Maternal expressed gene
- E.
New mutation
Correct Answer
C. Paternal expressed geneExplanation
Genetic imprinting refers to the phenomenon where certain genes are expressed differently depending on whether they are inherited from the mother or the father. In the given pedigrees, the presence of a paternal expressed gene can be explained by genetic imprinting. This means that the gene in question is only active when inherited from the father and not when inherited from the mother. This can result in specific traits or disorders being passed down in a family in a pattern that is consistent with the inheritance of a paternal expressed gene.Rate this question:
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- 16.
What rash is often described as a target lesion with a red center, pale zone and a outer dark ring. The lesions are generally symmetrical and may have itching?
- A.
Erythema multiforme
- B.
Erythema nodosum
- C.
Erythema rubra
- D.
Erythema
Correct Answer
A. Erythema multiformeExplanation
Erythema multiforme is often described as a target lesion with a red center, pale zone, and an outer dark ring. The lesions are generally symmetrical and may cause itching. This condition is characterized by the appearance of various skin lesions that can be triggered by infections, medications, or other factors. It is important to note that erythema multiforme is different from other types of erythema, such as erythema nodosum or erythema rubra, which have distinct characteristics and causes.Rate this question:
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- 17.
What is the term for dilated superficial blood vessels?
- A.
Hemangioma
- B.
Angiomia
- C.
Angiosarcorna
- D.
Telangiectasia
- E.
Alopecia
Correct Answer
D. TelangiectasiaExplanation
Telangiectasia is the term used to describe dilated superficial blood vessels. It is characterized by small, visible blood vessels that appear on the surface of the skin or mucous membranes. These blood vessels are often red or purple in color and can be seen in various parts of the body, such as the face, legs, or nose. Telangiectasia can be caused by various factors, including genetics, sun exposure, aging, and certain medical conditions. It is commonly seen in conditions like rosacea and hereditary hemorrhagic telangiectasia.Rate this question:
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- 18.
A 67 year old Caucasian woman presents with reddish papules and pustules on her cheek, nose and chin. She says that her face becomes worse if she uses hot water and during summers. What is the diagnosis?
- A.
Simple Acne
- B.
Acne vulgaris
- C.
Acne rosacea
- D.
Verruca vulgaris
- E.
Pemphigus vulgaris
Correct Answer
C. Acne rosaceaExplanation
Triggers that cause episodes of flushing and blushing play a part in the development of rosacea. Exposure to temperature extremes can cause the face to become flushed as well as strenuous exercise, heat from sunlight, severe sunburn, stress, anxiety, cold wind, and moving to a warm or hot environment from a cold one such as heated shops and offices during the winter. There are also some food and drinks that can trigger flushing, including alcohol, food and beverages containing caffeine (especially, hot tea and coffee), foods high in histamines and spicy food. Foods high in histamine (red wine, aged cheeses, yogurt, beer, cured pork products such as bacon, etc.) can even cause persistent facial flushing in those individuals without rosacea due to a separate condition, histamine intolerance.Rate this question:
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- 19.
The appearance of rashes or other skin lesions is indicative of cellular response to various types of challenges. Which one of the following skin reactions is most likely to be primarily due to an infectious disease process?
- A.
Impetigo
- B.
Miliaria rubra
- C.
Rosacea
- D.
Psoriasis
- E.
Miliaria crystalline
Correct Answer
A. ImpetigoExplanation
Impetigo is a highly contagious skin infection caused by bacteria, most commonly Staphylococcus aureus or Streptococcus pyogenes. It is characterized by the formation of red sores or blisters that can rupture and develop a yellowish-brown crust. The primary cause of impetigo is an infectious disease process, as it is caused by the invasion and multiplication of bacteria on the skin. Therefore, impetigo is the most likely skin reaction in this list to be primarily due to an infectious disease process.Rate this question:
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- 20.
A 17-year-old male developed a headaches (ever, chills, nausea, and muscle pain) 11/2 weeks after returning from a fishing trip with his father in Minnesota. During the interview, the patient remembers removing ticks from his skin. Laboratory investigations reveal elevated liver enzymes, thrombocytopenia, and leucopenia. The patient is treated with a 7-day course of doxycycline (100 mg every 12 hours) and recovers fully. Serological tests later confirm an infection with the intracellular, Gram-negative bacterium, Anapiasma phaaocytophilum, What is the vector of this disease
- A.
Ixodes oeciticus
- B.
Ixodes scapularis
- C.
Dermacentor variabilis
- D.
Ambiyornma americanum
- E.
Dermacentor andersoni
Correct Answer
B. Ixodes scapularisExplanation
Anaplasma phagocytophilum is a gram-negative bacterium that is unusual in its tropism to neutrophils. It causes anaplasmosis in sheep and cattle, also known as tick-borne fever and pasture fever, and also causes the zoonotic disease human granulocytic anaplasmosis.
Ixodes scapularis is commonly known as the deer tick or blacklegged tick and in some parts of the USA as the bear tick. It is a hard-bodied tick (family Ixodidae) of the eastern and northern Midwestern United States. It is a vector for several diseases of animals, including humans (Lyme disease, babesiosis, anaplasmosis, etc) and is known as the deer tick due to its habit of parasitizing the white-tailed deer.
Anaplasma phagocytophilum is a Gram-negative, obligate bacterium of neutrophils. It causes human granulocytic anaplasmosis, which is a tick-borne rickettsial disease. Because this bacterium invades neutrophils, it has a unique adaptation and pathogenetic mechanismRate this question:
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- 21.
A 27-year-old female presents with wheals on her neck (Image 1) caused by the organism shown in Image 2. What organism is this?
- A.
Ixodes sp. Tick
- B.
Body louse
- C.
Crab louse
- D.
Bed bug
- E.
Blister beetle
Correct Answer
D. Bed bugExplanation
The correct answer is Bed bug. The image shows wheals on the neck, which are a common symptom of bed bug bites. Bed bugs are small, oval-shaped insects that feed on the blood of humans and animals. They are usually found in beds, furniture, and cracks and crevices in walls. Bed bug bites can cause itching, redness, and swelling, and they often appear in a line or cluster.Rate this question:
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.JPG "In the drawing below, pick the cell (A, B, C, D, or E) that would be actively engaged in secreting lamellar bodies to waterproof the skin")
.JPG "Which of the cell types below is directly responsible for the formation of a keloid?")
.JPG "Martha is 31 she comes to a genetic clinic from a referral from her family physician. The
history below reveals several individuals with colon cancer on the side of her mother. Martha's mother died in an accident at the age of 38 and was known to be healthy. Martha explains that she is fine and she has been diagnosed with any health problem and she considers herself unlikely to be at risk of any problem. What is the most appropriate statement that the physician will provide to Martha?")
.JPG "Prader-Willi syndrome results from different molecular mechanisms. You have a patient that you suspect has this disorder and you send blood samples on the patient and both parents to the lab for genotyping using a DNA polymorphic marker located close to the centrorneric region on chromosome 15. The following genotypes are found. What is the most likely interpretation of this result? (F=-- father; P= patient; M= Mother)")
.JPG "How could the following pedigrees be explained by genetic imprinting?")
.JPG "A 27-year-old female presents with wheals on her neck (Image 1) caused by the organism shown in Image 2. What organism is this?")
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