Nutrition MD2 Block 1

A 4 day old male newborn is brought to the emergency department due to bleeding from the umbilical stump and blood in the stool. HE was born at home via spontaneous vaginal delivery at term. The parents declined all hospital procedures including vitamin K injection. The infant has been exclusively breast-fed. Lab studies: PT: prolonged; aPTT: prolonged ; Platelet count: normal; Fibrinogen: normal. Which of the following is the most likely cause of this infants bleeding

Impaired gamma-carboxylation of glutamate residues

A 67 year old man is brough tot the emergency department because of easy bruising and oozing from his gums. He was discharged 2 weeks ago after an episode of bacterial pneumonia and has been taking a broad spectrum antibiotic regiment. He reports poor appetite and mainly drinks nutritional shakes. He does not use alcohol. Exam shows multiple ecchymoses on the arms and legs, mild gum bleeding and no jaundice or ascites Which of the following best explains this patient's coagulopathy?

Inhibition of gamma-carboxylation of coagulation factors

A 2-month-old boy is brought to the emergency department due to irritability and vomiting. The patient is exclusively breastfed but has not been tolerating feeds since yesterday. Urine output has decreased. The mother has a history of obesity and had gastric bypass surgery several years prior to pregnancy. Temperature is 37°C (98.6°F), pulse is 190/min, and respirations are 60/min. The patient is in moderate respiratory distress and has an enlarged liver. Physical examination is otherwise normal. Chest radiography reveals cardiomegaly. Further workup shows impaired carbohydrate metabolism with increased serum levels of lactate and decreased erythrocyte transketolase activity. Which of the following additional enzymes is most likely to have impaired activity in this patient?

Pyruvate dehydrogenase

The question describes a 47-year-old homeless man with a history of heavy alcohol use and intravenous heroin use, presenting with paresthesias in his legs, painful oral lesions, glossitis, angular stomatitis, and hepatomegaly. Laboratory results show very low urinary riboflavin excretion, indicating riboflavin (vitamin B2) deficiency

Succinate dehydrogenase

52-year-old man with abdominal pain, watery diarrhea, depression, memory issues, a 20-year history of alcohol use disorder, and a pigmented scaly rash in sun-exposed areas (face, neck, hands). These symptoms are characteristic of pellagra, a condition caused by niacin (vitamin B3) deficiency

Isocitrate dehydrogenase

A 29-year-old man participates in a research study on nutrition and energy metabolism. For 6 weeks, he consumes an experimental diet that is severely restricted in many vitamins and micronutrients. He reports progressive fatigue, irritability, and numbness in his feet. Physical examination reveals mild hypotension, burning sensation in the lower limbs, and muscle cramps. Laboratory studies show no anemia or electrolyte abnormalities. An enzyme assay performed on his leukocytes demonstrates reduced activity of pyruvate dehydrogenase and α-ketoglutarate dehydrogenase complexes. Which of the following vitamin deficiencies best explains these findings?

Vitamin B₅ (Pantothenic acid)

A 2-month-old infant is brought for a routine checkup. He is exclusively breast-fed and is growing well. His birth weight has doubled. Which of the following statements best explains the high energy requirement during early infancy?

The brain utilizes about 60% of total energy intake

A 2-year-old child drinks 6 cups of cow's milk daily and eats few solids. She develops pallor and irritability. She is most likely deficient in:

Iron

A 13-year-old boy has experienced a rapid increase in height and appetite over the past year. Which hormonal change primarily drives the increased protein synthesis during puberty?

IGF-1 stimulated by GH

A 78-year-old woman has fatigue and tingling in her feet. She has long-standing reduced gastric acid secretion. Which nutrient is she MOST at risk of deficiency?

Vitamin B12

A 40-year-old sedentary man asks why his calorie needs seem stable compared with earlier stages of life. Which best explains the nutritional focus during adulthood?

Emphasis on metabolic stability and maintenance

A 2-month-old infant is brought for a routine checkup. He is exclusively breast-fed and is growing well. His birth weight has doubled. Which of the following statements best explains the high energy requirement during early infancy?

The brain utilizes about 60% of total energy intake

A 3-month-old infant presents with steatorrhea, failure to thrive, and acanthocytosis. Genetic testing shows absence of ApoB. What step is impaired?

Chylomicron formation in enterocytes

A 32-year-old man undergoes ileal resection for Crohn's disease. Which abnormality is expected?

Decreased bile salt recycling → impaired micelle formation

A patient with severe cystic fibrosis presents with malnutrition. Stool Sudan stain is positive. Which of the following digestive steps is most impaired?

Digestion of triglycerides into monoglyceride + free fatty acids

A 44-year-old woman undergoes cholecystectomy for gallstones. After surgery, she experiences mild steatorrhea after large fatty meals. Which mechanism best explains this?

Reduced micelle formation due to lack of concentrated bile release

A 6-year-old boy presents with intermittent ataxia, photosensitive rash, and emotional lability. Urinalysis reveals increased neutral amino acids. Dietary history shows adequate protein intake. Which step in protein utilization is defective?

Na+-dependent amino acid transport in the proximal tubule & intestine

During lactose intolerance, the bloating and flatulence is due to build-up of gases in the colon. Which of the following is responsible for this build-up of gases?

Decomposition of lactose in absence of oxygen

After carbohydrate digestion is complete, which of the following transporters helps in uptake of glucose across the mucosal cell?

Sodium dependent glucose transporter

A cell type is incubated in vitro with plenty of glucose and intracellular levels of glucose utilizing enzymes, intermediates and ATP formed are measured. It is observed that glycolysis of a molecule of glucose in these cells yields pyruvate, but net ATP is produced only for some molecules of glucose and not for others. Which of the following cells is most likely being studied in this experiment?

Erythrocytes

A 7-month-old full term baby is brought to the emergency with vomiting and lethargy. The parents mention to the attending that the little one was breast fed exclusively till 2 days ago when they added crushed fruits to his diet. The infant appears pale and diaphoretic. Diagnostic testing confirms aldolase B deficiency. Which of the following should be removed form the patient's diet?

Sucrose

A 62-year-old man with severe COPD is hospitalized with acute hypoxia. The patient is in respiratory distress and is treated with oxygen supplementation and bronchodilators. Laboratory studies show elevated serum lactate levels. Which of the following best explains the biochemical basis of his lactic acidosis?

Increased NADH/NAD+ ratio in cells

Arsenic inhibits pyruvate dehydrogenase by binding to which cofactor?

Lipoic acid

A cancer cell line continues high glycolytic activity even in the presence of oxygen. This is known as:

Warburg effect

5 day old baby is brought by her mother to the pediatrician due to progressive lethargy, vomiting, and poor feeding. The mothers pregnancy was uneventful and presently she is exclusively breastfeeding the baby. ON examination, the baby is somnolent, dehydrated, and with decreased muscle tone. Lab studies show a gap acidosis, hypoglycemia, and defective conversion of propionyl CoA to methyl malonyl CoA as reflected by elevated propionate levels.

Valine

A researcher studies fasting physiology in hepatocytes. She notices that when mitochondrial acetyl CoA levels rise

Pyruvate carboxylase

27 year old man is brought to the emergency department due to confusion. He has been binge drinking for the last 5 days and probably has had very little to eat. The patients medical history is significant for alcohol related seizures 1 year ago. He had been sober until 2 weeks ago, when he started drinking again.

Gluconeogenesis

A healthy 34 year old coal mine worker is trapped underground following partial collapse of an access shaft. Rescue efforts are directed toward clearing the obstructed Oxaloacetate -> Phosphoenolpyruvate A 6-month old girl is brought by her mother to the office for a check-up appointment. The mother states, "My baby doesn't seem to be growing much despite feeding as often as my previous children. I'm worried something is wrong with her." Height and weight are below the 10th percentile. Liver examination shows hepatomegaly and hepatosis. Laboratory results show hyperglycemia and ketocidosis. Liver biopsy shows hepatic fibrosis without fat accumulation. Further analysis reveals excessive amounts of abnormally structured polysaccharides within the cytosol of the hepatocytes. Which of the following enzymes is most likely deficient in this patient?

Glycogen debranching enzyme

A 20-year-old man is evaluated in the emergency department for weakness, malaise, and dark urine. The patient was treated for a bacterial skin infection several days ago. Physical examination shows scleral icterus. Laboratory results reveal anemia with an elevated reticulocyte count. Abnormal erythrocytes are seen on peripheral smear. Which of the following substrate flow pathways is most likely deficient in this patient?

C

A 5-month-old boy is brought to the office due to poor feeding. His mother says that he has difficulty holding his head up while breastfeeding and his sucking seems weaker than usual. Weight is at the 5th percentile. Length and head circumference are tracking along the 25th percentile. Physical examination shows hepatomegaly and hypotonia in all 4 limbs. Cardiac auscultation shows a gallop rhythm, and chest x-ray reveals severe cardiomegaly. Muscle biopsy shows enlarged lysosomes containing periodic acid-Schiff (PAS)-positive material. Which of the following enzymes is most likely deficient in this patient?

Acid alpha-glucosidase

A 6-month-old full-term boy is brought to the emergency department with lethargy and vomiting. He was born by uncomplicated spontaneous vaginal delivery and has been growing and developing normally. The patient was breastfed exclusively until 2 days ago when homemade pureed food was added to his diet. He has had no fever or diarrhea. His parents are healthy and he has had no sick contacts. Examination shows a pale, diaphoretic, and ill appearing infant. Serum glucose is 30 mg/dL. Diagnostic testing confirms aldolase B deficiency. Which of the following should be removed from this patient's diet?

Sucrose

A 15-year-old boy is brought to the clinic due to poor exercise endurance. He recently began weight lifting with friends but has had difficulty performing the exercises. The patient states that his arms "feel like jelly after just a few repetitions." He also has severe muscle cramping and has noticed occasional urine discoloration after training sessions. Further evaluation reveals that the patient's exercise tolerance can be greatly improved by drinking an oral glucose solution before beginning a strenuous activity. Vital signs are normal, and examination is unremarkable

A

A 6-month-old boy is brought to the emergency department by his mother because of recent onset of vomiting, irritability, and jaundice. The infant was born at term and had been healthy until the onset of these symptoms. All of his vaccinations are up-to-date. He had been breast-fed exclusively until 1 week ago, when cereals and fruit juices were introduced into his diet. Further evaluation reveals hepatomegaly and abnormal liver function tests. Which of the following enzymes is most likely to be deficient in this patient?

Aldolase B

An 11-year-old girl is evaluated for blurry vision. The patient was adopted internationally at age 9. She has no history of head or eye trauma or exposure to ionizing radiation. Motor and cognitive milestones have been achieved at the appropriate age. She has a good appetite and does not follow any specific diet. The patient takes no medications and has no allergies. Vaccinations are up to date. Vital signs are normal. She is at the 40th percentile for height and weight. Other than bilateral lens opacities,

Galactokinase

A 20-year-old man begins a rigorous endurance training program. During his training, his skeletal muscle glycogen stores must be rapidly replenished between sessions. Which enzyme is most directly activated by insulin in muscle to increase glycogen synthesis?

Glycogen synthase

In the liver during fasting, which hormonal cascade leads to increased activity of glycogen phosphorylase (i.e., increased glycogen breakdown)?

Glucagon → cAMP → PKA → phosphorylase kinase → glycogen phosphorylase

A newborn has vomiting and hypoglycemia soon after feeding milk. Lab shows elevated galactose in blood and urine. Enzyme assay reveals deficiency of galactose-1-phosphate uridyltransferase. Which of the following accumulates in the patient?

Galactose-1-phosphate and galactitol

The uronic acid pathway (glucose → glucuronic acid) is important for which of the following physiological processes?

Conjugation of bilirubin and xenobiotics in the liver

Which of the following correctly differentiates the uronic acid pathway from the pentose phosphate (hexose monophosphate) shunt?

Uronic acid pathway generates glucuronic acid used in detoxification; PPP produces NADPH & ribose-5-phosphate

The oxidative phase of the pentose phosphate pathway produces which key metabolite?

NADPH

A patient receives an intra-articular injection for osteoarthritis. The substance injected is a GAG that is NOT sulfated and NOT attached to a core protein. What is it?

Hyaluronic acid

Damage to a GAG in the cornea leads to vision impairment. Loss of which GAG disrupts corneal transparency?

Keratan sulfate

A patient with Gilbert syndrome is given a medication that is cleared by hepatic glucuronidation. Which metabolite produced by the uronic acid pathway is directly used in conjugation reactions to enhance excretion?

UDP-glucuronate (UDP-glucuronic acid)

A 2-year-old boy has developmental delay, hepatosplenomegaly, coarse facial features, and corneal clouding. Enzyme assay reveals α-L-iduronidase deficiency. Which GAGs accumulate?

Heparan sulfate and dermatan sulfate

A 3-year-old boy becomes irritable and sweaty every morning before breakfast. Labs during fasting show severe hypoglycemia, elevated lactate, and high levels of glycogen in the liver. Administration of glucagon does NOT raise his blood glucose. Which enzyme is most likely defective?

Glucose-6-phosphatase

A 7-month-old infant presents with hypotonia, failure to thrive, hepatosplenomegaly, and a biopsy showing long, unbranched glycogen chains with fewer α-1,6 linkages. Which disease is this?

Andersen disease

A nutritionist explains to a patient that one unit of energy equals the amount needed to raise the temperature of 1 kilogram of water by 1°C. This unit of energy is known as:

Kilocalorie

A 40-year-old man with obesity is advised to reduce dietary fat intake. He eats a snack that contains 47% of its total calories from fat. The snack has 9 g of fat. How many kcal are provided by fat in this snack?

81 kcal

A 34-year-old woman wants to understand why her daily caloric needs are higher than expected. Her total energy expenditure (TEE) is found to be mostly determined by the energy needed to maintain essential body functions at rest. This component typically accounts for which percentage of TEE?

50-70%

A nutrition researcher is determining the average daily intake of Vitamin C that meets the needs of 50% of the population. Which dietary reference intake is she calculating?

EAR

A 6-year-old boy from a rural area presents with difficulty seeing at night. His mother says he bumps into objects when the lights are dim. Examination shows dry, scaly skin and Bitot spots on the conjunctiva. Which of the following biochemical processes is most impaired?

Regeneration of rhodopsin in retinal rods

A 40 year old man presents with headache, blurry vision, and nausea. Fundoscopy reveals papilledema. He has been taking large amounts of a nutritional supplement containing retinol for immune support.

Dry, itchy skin, and alopecia

A 22 year old woman presents after an abnormal fetal ultrasound. She routinely takes an online purchased isotretinoin supplement for acne. SHe is now 9 weeks pregnant. Ultrasound reveals micrognathia, low0set malformed ears, conotruncal heart defect, and a lumbosacral neural tube defect.

Disruption of HOX gene expression affecting neural crest and neural tube patterning

A 7 year old malnourished child from a refugee camp presents with progressive vision problems. The image below shows the appearance of his conjuntiva. Which stage of vit A deficiency is deomonstrated?

Bitot spots formation

A 14-month-old boy is brought to the clinic because of delayed motor milestones. His mother reports that he has difficulty standing without support and often seems irritable. She states that he is still exclusively breast-fed and spends very little time outdoors. Physical examination reveals

Vitamin D deficiency (nutritional rickets)

A 6-day-old male infant is brought to the emergency department because of persistent oozing from the umbilical stump and bloody stool. He was delivered at home without medical assistance, and his parents refused all newborn interventions, including the vitamin K prophylaxis injection. The infant is exclusively breast-fed. On examination, he appears pale, with multiple bruises across the trunk and a small cephalohematoma. Laboratory results show: Prolonged PT Prolonged aPTT Normal platelet count Normal fibrinogen levels Which of the following best explains this infant's bleeding disorder?

Impaired γ-carboxylation of glutamate residues

A 35-year-old man enrolls in a metabolic nutrition study involving a diet severely deficient in several micronutrients for 6 weeks. He develops progressive fatigue, irritability, and tingling/burning sensations in his feet. He also reports muscle cramps, mild weakness climbing stairs, and occasional palpatations. On physical exam, he is mildly hypotensive with decreased ankle reflexes and distal neuropathy. Routine labs show normal electrolytes and no anemia. A leukocyte enzyme assay shows reduced activity of the pyruvate dehydrogenase complex and α-ketoglutarate dehydrogenase complex. Which vitamin deficiency best explains these findings?

Vitamin B1 (Thiamine)

A 42-year-old man living in a rural area presents with chronic diarrhea, worsening skin rash, and difficulty concentrating. Physical examination shows a hyperpigmented, scaly rash on the backs of his hands and forearms in a distribution that worsens with sun exposure as shown in picture. Neurologic exam reveals irritability and mild memory impairment. Which vitamin deficiency is most likely responsible for his condition?

Vitamin B3 (Niacin)

A protein found in raw eggs that causes a vitamin deficiency is:

Avidin; Biotin

A 45-year-old woman presents with fatigue, bleeding gums, perifollicular hemorrhages, and poor wound healing. She has a strict diet avoiding fruits and vegetables. Which biochemical reaction is most likely impaired?

Hydroxylation of lysine and proline residues in collagen

An experiment is conducted on isolated hepatocytes to study nitrogen metabolism. It is observed that glutamate transfers its amino group to oxaloacetate, forming a new compound that can be used for gluconeogenesis. Which substance is directly involved in this transfer reaction?

Pyriodoxal

Which of the following is classified as a trace element (micromineral) rather than a macro-mineral?

Zinc

Which of the following dietary components enhances the intestinal absorption of non-heme iron?

Vitamin C

A 22-year-old college student complains of fatigue and craving for ice. She follows a vegan diet and has heavy menstrual periods. Physical exam shows pale conjunctiva and spoon-shaped nails. Laboratory findings: Hemoglobin = 9 g/dL MCV = 70 fL Serum iron ↓ Ferritin ↓ TIBC ↑ Which of the following best describes the pathogenesis of this patient's anemia?

Decreased heme synthesis due to iron deficiency

A 67-year-old man with long-standing rheumatoid arthritis presents with mild fatigue. Labs show: Hemoglobin = 10 g/dL; Serum Fe ↓; Ferritin ↑; TIBC ↓. Which of the following mechanisms best explains these findings?

Cytokine-induced increase in hepcidin synthesis

A 2-month-old boy is brought to the emergency department due to irritability and vomiting. The patient is exclusively breastfed but has not been tolerating feeds since yesterday. Urine output has decreased. The mother has a history of obesity and had gastric bypass surgery several years prior to pregnancy. Temperature is 37°C (98.6°F), pulse is 190/min, and respirations are 60/min. The patient is in moderate respiratory distress and has an enlarged liver. Physical examination is otherwise normal. Chest radiography reveals cardiomegaly. Further workup shows impaired carbohydrate metabolism with increased serum levels of lactate and decreased erythrocyte transketolase activity. Which of the following additional enzymes is most likely to have impaired activity in this patient?

Pyruvate dehydrogenase

A 20-year-old male with anorexia presents with glossitis and scaly hair. He had been consuming a diet of sixteen raw eggs daily for 18 months. His symptoms cleared within 2–5 days after discontinuation of raw egg consumption. Which of the following vitamin deficiencies is most likely responsible for his condition?

Biotin

Which nutrient deficiency is most strongly associated with periorificial dermatitis (around the mouth and anus as shown in given picture), alopecia, and poor wound healing?

Zinc

A 7-month-old boy is brought to the clinic for poor feeding, hypotonia, and delayed developmental milestones. On exam, he has sparse, brittle, "kinky" hair and pale skin. His parents state that he has frequent fractures and does not gain weight despite adequate feeding. Laboratory studies:Serum copper: low; Ceruloplasmin: low; Serum zinc: normal. Which of the following mechanisms best explains this infant's condition?

Impaired copper transport due to ATP7A mutation

A 4-month-old infant comes for a routine checkup. He is exclusively breast-fed and continues to gain weight appropriately, now weighing nearly twice his birth weight. The pediatrician notes that infants require a much higher caloric intake per kilogram compared with older children. Which of the following statements best explains the high energy requirement during early infancy?

The brain utilizes about 60% of total energy intake

A 2-year-old child drinks 6 cups of cow's milk daily and eats few solids. She develops pallor and irritability. She is most likely deficient in:

Iron

A 13-year-old boy has experienced a rapid increase in height and appetite over the past year. Which hormonal change primarily drives the increased protein synthesis during puberty?

IGF-1 stimulated by GH

A 72-year-old woman presents with progressive fatigue and tingling sensations in her feet. She has a long-standing history of reduced gastric acid secretion due to chronic gastric atrophy. Which nutrient is she MOST at risk of deficiency?

Vitamin B12

After carbohydrate digestion is complete, which of the following transporters helps in uptake of Galactose across the mucosal cell?

SGLT1

During lactose intolerance, bloating and flatulence occur due to the accumulation of gases in the colon. Which of the following best explains the origin of these gases?

Fermentation of unabsorbed lactose by colonic bacteria

A 6-year-old boy presents with intermittent ataxia, photosensitive rash, and emotional lability. Urinalysis reveals increased neutral amino acids. Dietary history shows adequate protein intake. Which step in protein utilization is defective?

Na+ dependent amino acid transport in the proximal tubule & intestine

A 44-year-old woman undergoes cholecystectomy for gallstones. After surgery, she experiences mild steatorrhea after large fatty meals. Which mechanism best explains this?

Reduced micelle formation due to lack of concentrated bile release

A 23-year-old sprinter performs repeated high-intensity sprints. During anaerobic exercise, his skeletal muscles rely heavily on glycolysis, resulting in increased production of lactate. Which organ is primarily responsible for converting this lactate back into glucose to maintain blood glucose during exercise recovery?

Liver

A 62-year-old man with severe COPD is hospitalized with acute hypoxia. Labs show elevated serum lactate levels. Which of the following best explains the biochemical basis of his lactic acidosis?

Increased NADH/NAD+ ratio in cells

A cancer cell line continues high glycolytic activity even in the presence of oxygen. This is known as:

Warburg effect

A 3-day-old newborn is brought to the pediatrician due to worsening lethargy, vomiting, and poor feeding. She is exclusively breast-fed. Examination shows dehydration, hypotonia, and somnolence. Laboratory testing reveals high-anion gap metabolic acidosis, hypoglycemia, and markedly elevated propionate, consistent with an inability to convert propionyl-CoA to methylmalonyl-CoA. This defect prevents the infant from using which of the following amino acids for energy production?

Valine

A researcher is investigating the regulation of gluconeogenesis in liver cells during fasting. She observes that an increase in mitochondrial acetyl-CoA causes a significant rise in the conversion of pyruvate to oxaloacetate. Which of the following enzymes is being activated to promote gluconeogenesis?

Pyruvate carboxylase

Which of the following enzymes is unique to gluconeogenesis and not used in glycolysis?

Fructose-1,6-bisphosphatase

A marathon runner becomes hypoglycemic after prolonged fasting. His liver is actively converting alanine from muscle into glucose. Which pathway is being used?

Gluconeogenesis

A 9-month-old infant is brought to the clinic due to poor weight gain, recurrent respiratory infections, and progressive muscle weakness. The mother reports that the child tires easily during feeding and has had episodes of vomiting after meals. Physical examination shows hypotonia, hepatosplenomegaly, and diminished deep-tendon reflexes. Liver biopsy demonstrates long, unbranched glycogen chains with markedly reduced α-1,6 branching points. Which of the following is the most likely diagnosis?

Andersen disease

A 7-month-old girl is brought in for evaluation of poor growth. Her mother reports frequent feeding but minimal weight gain. The infant has hepatomegaly, truncal hypotonia, and episodes of vomiting, especially in the morning. Labs show hypoglycemia, ketoacidosis, and liver biopsy reveals fibrosis with cytosolic accumulation of abnormally structured glycogen lacking proper branching. Which enzyme is most likely deficient?

Glycogen debrancher enzyme

A 6-month-old boy presents with poor feeding, macroglottia, respiratory distress, and hypotonia. Exam shows a gallop rhythm and massive cardiomegaly on CXR. Muscle biopsy demonstrates PAS-positive material inside enlarged lysosomes. Which enzyme is most likely deficient?

Acid α-glucosidase

A 21-year-old athlete needs rapid post-exercise muscle glycogen replenishment. Insulin surges activate a key enzyme to promote glycogen synthesis. Which enzyme is directly activated?

Glycogen synthase

The uronic acid pathway (glucose → glucuronic acid) is crucial for which function?

Conjugation of bilirubin and detoxification

The oxidative phase of the pentose phosphate pathway produces:

NADPH

A 22-year-old man develops dark urine, jaundice, and fatigue two days after starting trimethoprim-sulfamethoxazole for a skin infection. Exam shows scleral icterus. Labs reveal: ↓ hemoglobin ↑ LDH ↑ indirect bilirubin ↓ haptoglobin Blood smear: bite cells and Heinz bodies. What is the most likely diagnosis?

G6PD Deficiency

A 4-month-old infant presents with jaundice that has persisted since birth. The infant is otherwise healthy. Laboratory evaluation shows elevated unconjugated bilirubin with normal liver enzymes. A defect is suspected in a pathway responsible for converting normal liver into a water-soluble form for excretion. Which of the following compounds or enzymes in the Uronic acid pathway is most directly required for bilirubin conjugation?

UDP-glucuronate (UDP-glucuronic acid)

A 6-month-old boy is brought to the emergency department by his mother because of recent onset of vomiting, irritability, and jaundice. The infant was born at term and had recent onset of vomiting, irritability, and jaundice. All of his vaccinations are up-to-date. He had been breast-fed exclusively until 1 week ago, when cereals and fruit juices were introduced into his diet. Further evaluation reveals hepatomegaly and abnormal liver function tests. Which of the following enzymes is most likely to be deficient in this patient?

Aldolase B

A 25-year-old male, recent immigrant to US who appears healthy, comes to the outpatient for a health check-up. History reveals that as a child he had a "problem with sugar metabolism". Currently he is not on any dietary restriction and eats plenty of fruits, meat, vegetables with good quantity of milk. At the outpatient, urine samples repeatedly test positive for reducing sugars but negative to glucose oxidase on urine dipstick. Which of the following enzymes is most likely to be deficient in this patient?

Fructokinase

An infant, within few days after first intake of milk, presents with severe diarrhea and vomiting. On physical examination, hepatomegaly is seen, cataracts are noted in the eyes of the infant and urine test confirms the diagnosis of the pediatrician. Pediatrician advises immediate withdrawal of lactose from the diet of the infant. Which of the following enzymes is deficient in this infant?

Galactose-1-phosphate uridyl transferase

A 3-year-old boy recently died from myocardial infarction. He had a history of intellectual disability. Autopsy reveals cardiomegaly and hepatosplenomegaly as well as diffuse haze over the corneas bilaterally. Which of the following would you expect to accumulate in the coronary arteries?

Dermatan Sulfate

A 5-year-old child presents with short stature, skeletal dysplasia, kyphosis, and normal intellect. Corneal clouding is present. GAG analysis shows increased keratan sulfate. Which enzyme deficiency is most consistent?

Galactose-6-sulfatase

Chronic alcoholism causes fatty liver primarily because increased NADH:

Converts OAA → malate, inhibiting the TCA cycle

A deficiency of Δ6-desaturase leads to decreased synthesis of essential fatty acids. Which clinical presentation is expected?

Scalp Dermatitis

A 23-year-old woman eats a high-carbohydrate meal. One hour later, she has increased insulin secretion. Laboratory analysis of her liver shows increased production of malonyl-CoA. Which enzyme is activated under these conditions?

Acetyl-CoA carboxylase