Deck 42: Iron and Copper Metabolism

Question 1

A 3-month-old infant is brought to the doctor by distraught parents who indicate that they feel there is something seriously wrong with the child. The baby is not thriving, demonstrates clear neurodegenerative deficit, and has a cherubic face with sagging jowls and no eyebrows. The infant's hair is gray and has the appearance and feel of steel wool. This constellation of symptoms is associated with which of the following disorders?

A) acute intermittent porphyria (AIP)
B) hemochromatosis type 1
C) Menkes disease
D) porphyria cutanea tarda (PCT)
E) Wilson disease

Answer 1

Menkes disease

Question 2

A 3-month-old infant who otherwise appeared normal during the first 2 months of life except for a bout of hyperbilirubinemia is now clearly exhibiting developmental delay. In addition, the infant's hair has become grayish and dull and there is a stubble of broken hair over the occiput and temporal regions. The facial appearance has also changed such that the infant has very pudgy cheeks, abnormal eyebrows, and sagging jowls. The occurrence of frequent convulsions was the stimulus for the parents to bring their child to the emergency room. These rapidly deteriorating symptoms are indicative of which of the following disorders?

A) Crigler-Najjar syndrome type I
B) Gilbert syndrome
C) hemochromatosis
D) Menkes disease
E) Refsum disease

Answer 2

Menkes disease

Question 3

Your patient is a 25-year-old woman who is experiencing difficulty speaking, clumsiness while walking, uncontrolled twitching in her arms, fatigue, and depression. Physical examination shows distinct jaundice in skin and the eyes as well as a discoloration in the periphery of the cornea. These signs and symptoms are most likely indicative of which of the following disorders?

A) acute intermittent porphyria (AIP)
B) hemochromatosis type 1
C) Menkes disease
D) porphyria cutanea tarda (PCT)
E) Wilson disease

Answer 3

Wilson disease

Question 4

You are tending to a 40-year-old male patient complaining of severe abdominal pain, lack of energy, diminished sex drive, weight loss, and generalized weakness. You note a general darkening of the skin making it look bronze in color. Suspecting an iron overload, you prescribe addition tests because you believe the patient is most likely suffering from which of the following disorders?

A) type 1 hemochromatosis (HFE1 gene defect)
B) type 2A hemochromatosis (hemojuvelin gene defect)
C) type 2B hemochromatosis (hepcidin gene defect)
D) type 4 hemochromatosis (ferroportin gene defect)

Question 5

You are tending to a 27-year-old male patient presenting with hypogonadism and cardiomyopathy. Additional testing has confirmed that the patient is suffering from juvenile hemochromatosis type 2A. This disorder results from a defect in the gene encoding the hemojuvelin protein. The expression of which of the following proteins would likely be unregulated in this patient?

A) ceruloplasmin
B) ferroportin
C) hephaestin
D) hepcidin
E) transferrin receptor

Question 6

You are treating a 30-year-old patient for acute hepatitis and progressive chronic liver disease. Your patient also shows parkinsonian tremors, diminished facial muscle movement, and choreoathetosis. In taking the patient history you learn that he has become progressively more depressed and paranoid. Which of the following disorders most likely explains the signs and symptoms observed in this patient?

A) aceruloplasminemia
B) GRACILE syndrome
C) hemochromatosis
D) Menkes disease
E) Wilson disease

Question 7

Transport of iron from within intestinal enterocytes to the circulation requires that it be oxidized from the ferrous to the ferric form. This oxidation is catalyzed by which of the following proteins?

A) ceruloplasmin
B) DMT1
C) ferroportin
D) heme oxygenase
E) hephaestin

Question 8

Hemochromatosis, a disorder that is the result of excess iron accumulation, is caused by deficiencies in which of the following proteins?

A) divalent metal transporter 1 (DMT1)
B) HLA complex iron protein (HFE)
C) ferritin
D) ferroportin
E) transferrin

Question 9

Loss of the hepatic protein hepcidin can lead to severe iron overload with symptoms resembling those of hemochromatosis. Which of the following functions of hepcidin accounts for the iron overload when the protein is deficient?

A) activates the expression of the iron-response element binding protein that regulates transferring receptor and ferritin mRNA translation
B) decreases the level of intestinal membrane iron transporters, resulting in reduced iron uptake
C) facilitation of the interaction of transferrin with the transferrin receptor
D) forms a complex with ferritin allowing for higher intracellular storage
E) promotes the formation of hemosiderin, thus detoxifying iron

Question 10

The level of iron in the body must be tightly regulated due to the severe toxicity associated with elevated levels in the circulation and within cells. Which of the following proteins is primarily responsible for iron homeostasis?

A) ceruloplasmin
B) haptoglobin
C) metallothionein
D) α₂-macroglobulin
E) transferrin

Question 11

Regulation of iron homeostasis occurs by controlling the amount that circulates in the serum as well as the amount contained within cells. One mechanism that plays a role in this homeostasis is iron-mediated control of the level of the intracellular iron-binding protein ferritin. Which of the following represents the mechanism of iron regulation of ferritin levels?

A) binding of iron to ferritin leads to secretion of the complex from cells and subsequent excretion in the urine
B) ferritin exists as a tetramer and when iron binds, the affinity for additional iron atoms increases
C) iron binds an additional protein that acts as a regulator of ferritin mRNA translation, high iron leads to increased translation and thus increased iron-binding capacity
D) when excess iron binds to ferritin it decreases the half-life of the protein allowing the iron to be released to the plasma and excreted

Question 12

A 29-year-old man is being examined by his physician to determine the cause of his progressing tremors. His physician notes that the man has a diminished capacity to move his facial muscles and that the tremors in his arms are indicative of choreoathetosis. Serum analysis shows significantly elevated AST and ALT. Ophthalmic examination indicates that the patient has Keyser-Fleischer rings in his corneas suggesting he is suffering from Wilson disease. The lack of which of the following processes would most likely be found in this patient?

A) copper incorporation into ceruloplasmin
B) copper storage in renal tubule cells
C) copper transfer into the brain
D) copper transport from within intestinal enterocytes into the portal circulation
E) copper uptake by intestinal enterocytes

Question 13

The parents of a 4-month-old infant bring their child to his pediatrician because they are concerned about his difficulty in feeding, irritability, and his overall floppiness. The pediatrician notes that the infant has pudgy, rosy, cheeks and brittle, easily broken hair. The doctor suspects the child is suffering from Menkes disease. Given that the physician is correct in her diagnosis, the lack of which of the following would likely be found in this patient?

A) copper incorporation into ceruloplasmin
B) copper storage in hepatocytes
C) copper transfer into the biliary circulation
D) copper transport from within intestinal enterocytes into the portal circulation
E) copper uptake by intestinal enterocytes

Question 14

You are examining a patient manifesting symptoms typically seen in one suffering from severe hemochromatosis including slurred speech, memory impairment, ataxia, and dementia as well as bronze diabetes. Genetic analysis and examination of plasma proteins indicate the patient does not have the typical causes of iron overload. Which of the following proteins is most likely absent or defective in this patient that would explain the observed symptoms?

A) ceruloplasmin
B) ferritin
C) ferroportin
D) hephaestin
E) transferrin

Question 15

Loss or deficiency in which of the following proteins would result in the inability of transferrin bind and transport iron in the blood?

A) duodenal cytochrome b (DCYTB)
B) ferritin
C) ferroportin
D) heme oxygenase
E) hephaestin

Question 16

You are examining a 44-year-old male patient who appears anemic. Blood work indicates his hemoglobin level is 12.2 g/dL (normal is 15.5 g/dL) and his erythrocytes are microcytic (mean corpuscular volume [MCV] = 70 fL, with normal MCV = 80-100 fL). Given these findings, which of the following would most likely be present in this patient?

A) acute bleeding
B) folate deficiency
C) iron deficiency
D) vitamin B₁₂ deficiency
E) vitamin K deficiency

Question 17

Delivery of iron to cells by receptor-medicated endocytosis requires which of the following?

A) albumin
B) cytochrome a₁
C) ferredoxin
D) ferritin
E) transferrin

Question 18

The primary iron storage molecule in cells is which of the following?

A) albumin
B) ferredoxin
C) ferritin
D) haptoglobin
E) transferrin

Question 19

A 3-month-old infant who was born at 34 weeks' gestation is being breast-fed. Mean corpuscular volume (MCV) is 70 μm3 (normal = 80-100), and mean corpuscular hemoglobin concentration (MHC) is 28% (normal = 30-34). The infant should receive an oral supplement of which of the following?

A) copper
B) fluoride
C) folate
D) iron
E) selenium