A 6-month-old infant has been exclusively fed a commercially available infant formula. Upon introduction of fruit juices, however, the child develops jaundice, hepatomegaly, vomiting, lethargy, irritability, and seizures. Tests for urine-reducing substances are positive. Which of the following is likely to explain this child’s condition?
e. Glucose-6-phosphatase deficiency
the answer is below…
The United States Medical Licensing Examination, or USMLE for short, is a three-part licensing examination that is required in order to receive a license to practice medicine within the United States.
The USMLE assesses a physician’s ability to apply knowledge, concepts, and principles, and to determine fundamental patient-centered skills that are important in health and disease and that constitute the basis of safe and effective patient care.Examination committees composed of medical educators and clinicians from across the United States and its territories prepare the examination materials each year.
This exam is designed by the Federation of State Medical Boards and the National Board of Medical Examiners to determine whether or not an individual understands and can apply the knowledge necessary to practice medicine safely and intelligently.
The USMLE is actually comprised of three different exams that are referred to as steps, which examine the individual’s knowledge of specific topics related to the field of medicine such as basic science, medical knowledge, medical skills, clinical science, and the application of all of these skills and areas of knowledge in the medical field.
All three steps of the USMLE include a series of computerized multiple-choice questions, but the format of the exam and the information covered in each multiple-choice section is different for each step of the USMLE. The USMLE Step II also has a clinical skills portion that examines an individual’s ability to work with real patients and the USMLE Step III has a computerized patient simulation portion in addition to the multiple-choice section of the exam. In order for an individual to receive a license to practice medicine, the individual must pass all three steps of the USMLE.
The answer is c; Fructosemia.[1-3]
The patient in the question likely has fructosemia, manifest only when fructose in fruit juice is provided in the diet. Galactosemia, fructosemia, tyrosinosis, and glucose-6-phosphatase deficiency represent diseases in which a congenital deficiency of enzyme causes an interruption of a normal metabolic pathway and an accumulation of metabolic precursors that damage vital organs. Galactosemia (found in milk) and fructosemia (found in fruit juices) produce urinary-reducing substances. The mode of inheritance of galactosemia, fructosemia, and most forms of glucose-6-phosphatase deficiency is autosomal recessive. In galactosemia and fructosemia, errors in carbohydrate metabolism cause the accumulation of toxic metabolites when specific dietary sugars are introduced (lactose in galactosemia; fructose and sucrose in fructosemia). Exclusion of the offending carbohydrate from the diet will prevent liver damage. In tyrosinemia type I, or tyrosinosis, the accumulation of tyrosine and its metabolites is associated with severe involvement of liver, kidney, and central nervous system (CNS). Manifestations of acute liver failure can appear in infancy. A chronic form of the disorder presents as progressive cirrhosis and leads to liver failure or hepatoma. Dietary management does not prevent liver disease. Glucose-6-phosphatase deficiency often presents at 3 to 4 months of age with failure to thrive, hypoglycemia, hepatomegaly, and acidosis. Alpha-1-antitrypsin deficiency causes liver disease through accumulation of an abnormal protein, caused by a single amino acid substitution on chromosome 14. It has a variable presentation, but the following are common in infancy: cholestasis; bleeding into the CNS, GI tract, or at the umbilical stump; and elevation of transaminase concentrations. In childhood, a picture of chronic hepatitis with cirrhosis and portal hypertension is seen.