A skin lesion on the upper eyelid of a 46-year-old woman is biopsied.  Light microscopy of the tissue specimen is shown in the image below.

This lesion is most likely to be associated with which of the following conditions?

A cross-section of the right coronary artery of a 34-year-old Caucasian male who died in the cardiac intensive care unit is shown on the slide below.

His father died of a heart attack at the age of 40.  Assuming this patient’s disease had a genetic basis, poor receptor expression in which of the following organs is most likely responsible for his condition?

A 4-month-old boy is being evaluated for a hereditary metabolic disorder after presenting with failure to thrive and developmental delay.  He was born outside the United States and had several seizures during the neonatal period.  Physical examination reveals an abnormal head shape with a large anterior fontanelle and widely splayed cranial sutures.  Profound hypotonia and hepatomegaly are also noted.  Biochemical studies show elevated levels of very long chain fatty acids (VLCFAs) and phytanic acid.  Cultured skin fibroblasts show impaired ability to oxidize VLCFAs.  This patient’s condition is best explained by dysfunction of which of the following cellular structures?

An 8-month-old girl is brought to the office due to irritability and regression of motor skills.  The patient’s birth was unremarkable and her development had appeared normal, but she can no longer sit or roll over.  Her parents have also noticed that she startles easily at loud noises.  Head circumference measurement is consistent with macrocephaly.  Bilateral funduscopic evaluation shows a bright red fovea centralis that is surrounded by a contrasting white macula.  Peripheral vision is decreased.  Abdominal examination is normal.  Accumulation of which of the following metabolites is most likely present in this patient’s tissues?

 34-year-old man is found to have an LDL level of 310 mg/dL and a normal serum triglyceride level.  His father suffered a myocardial infarction at age 39, and his paternal grandfather died of a heart attack at age 40.  The patient’s wife has a normal lipid profile.  DNA samples are obtained from several family members for genetic analysis.  Southern blotting of restriction fragments from a region containing the LDL receptor gene shows the following pattern:

Which of the following statements best describes the DNA analysis results?

An 18-month-old boy is being evaluated for neurologic regression.  He had a normal neonatal course and early development until age 5 months.  The boy subsequently experienced gradual regression of developmental milestones, and now has inability to sit with support, poor head control, and loss of a social smile.  Weight and height are below the 5^th percentile.  Physical examination shows an enlarged liver and spleen, diminished deep tendon reflexes in all limbs, and hypotonia.  Funduscopic findings are shown in the exhibit.  This patient most likely has an accumulation of which of the following substrates?

An 18-year-old girl with a history of type 1 diabetes mellitus comes to the emergency department after several hours of nausea, vomiting, and abdominal pain.  The patient reports that she is on vacation visiting friends and has not taken insulin in the last 2 days.  Physical examination shows breath with fruity odor and dry mucosal membranes.  Laboratory studies show a blood glucose level of 452 mg/dL and high anion gap metabolic acidosis.  Urinalysis is positive for ketones.  It is determined that the patient’s insulin deficiency is causing increased production of gluconeogenic precursors that are subsequently converted to glucose in the liver.  Which of the following enzymes is most likely to provide these precursor substrates?

An 8-year-old boy is brought to the emergency department due to vomiting and lethargy.  The patient had been on an overnight hiking trip with his family.  During the trip, the family lost their food pack while canoeing and had to hike back to their car.  The child became weak and was carried for the last mile.  None of the family has eaten for approximately 24 hours.  On examination, the patient appears listless.  Mild hepatomegaly is noted.  Laboratory results are as follows:

The patient begins seizing shortly after arriving at the emergency department.  Which of the following enzymes is most likely deficient in this patient?

A 5-year-old girl is brought to the clinic due to several months of fatigue and difficulty walking.  She ambulates normally at first but rapidly becomes weak and tired.  The patient has not been ill recently and is usually happy and playful.  She has a history of mild motor delays but is otherwise developmentally normal.  Vital signs are within normal limits.  Examination shows mildly decreased power in all extremities but no ataxia.  Cardiac auscultation reveals a 1/6 systolic murmur and an S3 gallop.  Laboratory results are as follows:

Muscle biopsy shows a very low carnitine content.  This patient most likely has deficient synthesis of which of the following substances?

A 42-year-old woman comes to the physician for a routine check-up.  She has no current complaints and no significant past medical history.  On physical examination, the physician notes lesions on her eyelids that are pictured below.

Which of the following is the best next step in the management of this patient?

A research scientist studying the metabolic pathways that contribute to obesity feeds experimental animals a high-carbohydrate, high-protein diet for a prolonged period.  A sample of liver tissue is then obtained from the animals, and the activity of various enzymes involved in fatty acid metabolism is measured and recorded.  It is determined that beta-oxidation of fatty acids is inhibited within these cells as a result of the diet.  An increase in which of the following substances is most likely responsible for the observed effect?

A 36-year-old man comes to the office due to skin lesions on his palms.  The patient has yellowish skin nodules over the palmar creases that have been increasing in size and number over the past several years.  He also has small clusters of yellow papules on his elbows, knees, and buttocks.  His father died of a myocardial infarction at age 56.  Biopsy of his lesions shows accumulation of lipid-laden macrophages.  Immunoblot analysis suggests a lack of ApoE3 and ApoE4 in his circulating lipoproteins.  Which of the following is most likely impaired in this patient?

A 72-year-old woman is brought to the emergency department after lying on the floor in her home for the past 2 days.  The patient’s neighbor called police after phone calls were not answered and no one opened the door.  She was found awake on the bathroom floor lying in feces and urine.  The patient says she fell and injured her right hip and was unable to get up to call for help.  She did not eat or drink anything during that time.  On examination, the patient appears dehydrated and has right hip tenderness.  Laboratory studies show serum glucose of 72 mg/dL and positive urine ketones.  Radiographs of the right hip show a right femoral neck fracture.  Increased activity of which of the following enzymes is most likely contributing to both the serum and urine laboratory findings?

A 24-year-old woman is admitted to the hospital with a diagnosis of acute appendicitis.  She started having right lower quadrant abdominal pain approximately 30 hours earlier but did not go to the hospital because she thought the pain would subside on its own.  The patient had no food, only sips of water, during that time.  Blood pressure is 115/72 mm Hg and pulse is 106/min.  Mucous membranes are dry and there is tenderness in the right lower quadrant of the abdomen.  Laboratory evaluation shows mild leukocytosis, normal serum electrolytes, borderline low serum glucose levels, and moderate ketones in the urine.  Based on the evaluation, it is suspected that this patient is utilizing ketone bodies as a significant reserve of energy.  Which of the following tissues cannot use this energy source?

A 5-month-old boy is being evaluated for poor weight gain since birth.  He is noted to have bulky and greasy stools.  A jejunal biopsy shows the findings seen in the slide below.

Which of the following is the most likely diagnosis?