Chapter 6: Developmental and Genetic Dz Flashcards
(42 cards)
A 4-year-old girl presents for a preschool physical examination.
The child has a small head circumference, thin upper lip,
and low-bridge nose. She shows evidence of mild mental
retardation. Her parents state that she is often “emotional.”
Which of the following maternal causes of birth defects most
likely accounts for these clinicopathologic fi ndings?
(A) Alcohol abuse
(B) Cigarette smoking
(C) Congenital syphilis
(D) Inadequate nutrition
(E) Poorly controlled diabetes mellitus
- Alcohol abuse.
A 12-month-old boy is brought to the emergency room for
examination of his right arm following a tumble at home.
Radiologic examination of the limb reveals a recent fracture
of the right ulna and evidence of additional healing fractures.
The child is noted to have blue sclerae. This patient most
likely carries a mutation in a gene that encodes which of the
following proteins?
(A) Collagen
(B) Fibrillin
(C) Keratin
(D) Myosin
(E) Tubulin
- Collagen.
A 28-year-old woman gives birth to a stillborn with a severe
neural tube defect (neonate shown in the image). This birth
defect was caused by an error of morphogenesis that occurred at
which of the following stages of development after fertilization?
- 20 to 40 days.
A 20-year-old man is examined by a new family physician who
discovers numerous pigmented patches and pedunculated
skin tumors on his chest. Biopsy of a tumor discloses a benign
neoplasm derived from Schwann cells. Neither the patient’s
father nor mother shows signs of this disease. This patient
most likely carries a mutation in a gene that encodes which of
the following proteins?
(A) Epidermal growth factor receptor
(B) GTPase activating protein
(C) NF-κB transcription factor
(D) Protein kinase C
(E) Ras protein p21
- GTPase activating protein.
The patient described in Question 4 is at increased risk of
developing which of the following malignant neoplasms?
(A) Ganglioneuroma
(B) Glioblastoma multiforme
(C) Neurofi brosarcoma
(D) Serous cystadenocarcinoma
(E) Squamous cell carcinoma
- Neurofibrosarcoma.
A 25-year-old pregnant woman, at 16 weeks of gestation, visits
her obstetrician. A screening test suggests the possibility of a
neural tube defect in her fetus. An ultrasound examination
shows a 3-cm neural tube defect in the thoracic spine. The
screening test that was administered to the mother measured
serum levels of which of the following proteins?
- Alpha-fetoprotein (AFP).
A 25-year-old man presents for a routine physical examination.
The patient is tall (6 ft, 5 in) and has long fi ngers (shown
in the image). One year later, he suffers a dissecting aortic
aneurysm. This patient most likely carries a mutation in a
gene that encodes which of the following proteins?
- Fibrillin
The genetic disease encountered in the patient described
in Question 7 follows which of the following patterns of
inheritance
- Autosomal dominant.
A 12-month-old boy shows progressive weakness, mental
deterioration, and loss of vision. Laboratory studies
demonstrate decreased activity of hexosaminidase A. The child
eventually becomes blind and dies at 3 years of age. Which
of the following best describes the pathogenesis of neuronal
degeneration in this patient?
(A) Accumulation of unmetabolized substrate
(B) Decreased utilization of metabolic end-product
(C) Formation of an abnormal metabolic end-product
(D) Opening of mitochondrial membrane pore
(E) Synthesis of a novel glycosphingolipid
- Accumulation of unmetabolized substrate.
If the parents of the child described in Question 9 have a total
of four sons and two daughters, then, on average, how many
of their children may be expected to be asymptomatic (i.e.,
silent) carriers of this gene mutation?
- Three children.
A 4-year-old boy is admitted to the hospital with pneumonia
and respiratory distress. The nurses report that the child’s
bowel movements are greasy and have a pungent odor. A sweatchloride
test is positive. Which of the following mechanisms
of disease is the most likely cause of steatorrhea in this child?
- Lack of pancreatic enzyme secretion.
The patient described in Question 11 carries mutations in the
gene that encodes which of the following types of protein?
(A) Membrane ion channel
(E) Receptor tyrosine kinase
- Membrane ion channel
A 10-year-old child presents with xanthomas on the extensor
surfaces of his forearms. Laboratory studies demonstrate a
total serum cholesterol of 820 mg/dL. The child’s mother and
maternal grandfather also have elevated serum cholesterol.
This patient most likely has mutations in the gene that
encodes which of the following proteins involved in lipid
metabolism?
(A) ApoE4
(B) Cholesterol hydroxylase
(C) Chylomicron transport protein
(D) High-density lipoprotein receptor
(E) Low-density lipoprotein receptor
- Low-density lipoprotein (LDL) receptor.
A 10-month-old boy who was adopted from an orphanage
in Eastern Europe presents for a physical examination. His
parents believe that he is failing to meet developmental
milestones. The child is fair skinned and has blond hair. On
physical examination, the patient is noted to have a “mousy”
odor. Laboratory studies demonstrate an inborn error of
amino acid metabolism. To prevent mental retardation, this
patient should be placed on a special diet that lacks which of
the following essential amino acids?
- Phenylalanine.
Which of the following best describes the pathogenesis of
mental retardation in the patient described in Question 14?
(A) Accumulation of unmetabolized substrate
(B) Decreased utilization of metabolic end-product
(C) Formation of an abnormal metabolic end-product
(D) Increased utilization of metabolic end-product
(E) Opening of mitochondrial membrane pore
- Accumulation of unmetabolized substrate.
A 4-year-old boy is found to have extremely pliable skin.
His parents note that he bruises easily. His joints can
be hyperextended. Biochemical studies demonstrate a
defi ciency of lysyl hydroxylase. Ultrastructural examination
of a skin biopsy of this patient would most likely reveal
abnormalities associated with which of the following cell/
tissue components?
- Collagen fibers.
A 25-year-old woman complains of recurrent bone pain and
increasing abdominal girth. Physical examination reveals
massive hepatosplenomegaly. Radiologic studies reveal
several radiolucent bone defects. A bone marrow biopsy
discloses enlarged cells with a fi brillar appearance reminiscent
of “wrinkled tissue paper.” Microscopic examination of a
splenectomy specimen is shown. This patient most likely
carries mutations in the gene that encodes which of the
following types of hydrolytic enzymes?
- Glucosidase
Which of the following best describes the pathogenesis of
hepatosplenomegaly and bone pain in the patient described in
Question 17?
(
- Accumulation of unmetabolized substrate.
A neonate is born with severe motor dysfunction involving
the lower extremities. Radiologic studies show that vertebral
bodies in the lumbar region lack posterior arches. The
vertebral defects are covered by a thin membrane. The space
underneath the membrane contains a mass of tissue that is
composed of meninges and spinal cord. The parents ask for
information regarding risks for similar birth defects in their
future offspring. You mention that dietary supplementation of
the maternal diet has been shown to reduce the incidence of
neural tube defects. What is this substance?
- Folic acid.
The parents of an infant with cleft lip and palate (infant shown
in the image) visit a genetic counselor to discuss the chance
that a similar birth defect will occur in their future offspring. In
addition to teratogen exposure and multifactorial inheritance,
which of the following is an important cause of this error of
morphogenesis?
- Structural chromosomal abnormality
A 4-year-old boy is brought to the physician by his parents
because he tires easily. Physical examination reveals weakness
in the pelvic and shoulder girdles and enlargement of the
child’s calf muscle. Serum levels of creatine kinase are
elevated. A biopsy of calf muscle shows marked variation
in size and shape of muscle fi bers. There are foci of muscle
fi ber necrosis, with myophagocytosis, regenerating fi bers, and
fi brosis. Molecular diagnostic assays would most likely show
alterations in the length of the primary transcript for which of
the following muscle-associated proteins?
- Dystrophin
What will be the likely cause of death in the patient described in Question 21? (A) Cardiomyopathy (B) Cerebrovascular disease (C) End-stage renal disease (D) Pulmonary saddle embolism (E) Respiratory insuffi ciency
- Cardiomyopathy
A 22-year-old man complains about his inability to conceive a
child. On physical examination, the patient is noted to be tall (6 ft, 5 in) and exhibits gynecomastia and testicular atrophy.
Laboratory studies demonstrate increased serum levels of
follicle-stimulating hormone. Cytogenetic studies reveal a
chromosomal abnormality. What is the most common cause
of this patient’s chromosomal abnormality?
- Meiotic nondisjunction
A 35-year-old pregnant woman delivers a baby prematurely at
28 weeks of gestation. Shortly after birth, the neonate becomes
short of breath, with intercostal retraction and nasal fl aring
during respiration. The neonate is placed on a ventilator,
but dies of respiratory insuffi ciency and intraventricular
hemorrhage. Microscopic examination of the lungs at
autopsy is shown. The eosinophilic material lining the air
spaces represents an accumulation of which of the following
proteins?
- Fibrin
