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32 Cards in this Set
- Front
- Back
What is an inborn error of metabolism? |
A genetic condition which impairs the body's ability to metabolize biological substances |
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What are IMDs? |
Inborn metabolic diseases |
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What define IMDs? |
Diseases due to the absence, inactivity, or reduced activity of proteins which regulate metabolic pathways |
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What are some examples of metabolic pathways? |
The Krebs cycle, glycolysis, amino acid catabolism, glycoprotein synthesis, fatty acid oxidation, urea cycle |
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What is Garrod's hypothesis? |
The idea that having a toxic excess of substrate will cause improper conversion to the intended product, instead producing a different toxic metabolite |
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What are the two effects resulting from substrate excess, according to Garrod's theory? |
An increase of toxic metabolite and a deficiency of product (structural, energy) |
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How are IMDs classified? |
By the type of molecule and cell organelle effected, or by the affected metabolic pathway |
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What type of inheritance generally causes IMDs? |
Autosomal recessive genes |
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What inheritance types can cause IMDs? |
Autosomal recessive or dominant genes, X-linked disorders, maternal mitochondrial DNA |
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How common are IMDS? |
Individually rare, collectively common |
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When do most IMDs present? |
Neonatal period |
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How severe are neonatal IMDs? |
Generally acute and life-threatening |
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When is it least common for IMDs to present? |
Adulthood |
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What makes neonatal IMDs hard to detect? |
Non-specific presentation-- can be mistaken for infection or sepsis |
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What are the 4 broad groups of clinical presentation? |
Secondary accumulation of toxins, enegy deprivation, liver disfunction with hypoglycemia, dysmorphism |
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What is common in the clinical presentation of IMDs? |
Overlap of symptoms (4 broad groups) |
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Why is there often a delay in disease onset for infants with IMDs? |
Because toxin accumulation takes place over 2-3 days before becoming dangerous |
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What are the symptoms of IMD intoxication? |
Vomiting, lethargy, coma, liver failure, acidsosi, hyperammonemia, hypoglycemia |
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An infant presents with vomiting, rapid breathing, lethargy, dehydration, fever, and weight loss a day or two after birth. What is the most likely cause? |
Intoxication secondary to an IMD |
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How does an IMD with secondary energy deprivation present? |
Immediate issues with hypoglycemia, sudden death in neonates |
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What tissues are affected in an IMD with secondary energy deprivation? |
Metabolically active tissues (liver, muscle, brain) |
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What are the symptoms of an IMD with secondary energy deprivation in older children? |
Floppiness, heart failure, cardiomyopathy, high lactic acid |
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How is an IMD with secondary energy deprivation treated? |
Energy supplements (e.g. glucose infusion), frequent eating |
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A young child presents with floppiness, hypoglycaemia, and seizures after not eating for 18 hours. What is the most likely cause? |
IMD with secondary energy deprivation |
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How does an IMD with secondary liver failure and hypoglycaemia present? |
Seizures, acidosis and ketosis, hepatomegaly |
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A 6 week old infant presents with vomiting, hepatomegaly, jaundice, and cataracts. What is the most likely cause? |
Liver failure secondary to an IMD |
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How does an IMD with secondary dysmorphism present? |
Slow development, abnormal face or body features, hepatomegaly |
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A young child presents with slow development, frequent infections, hepatomegaly, and a deformed face. What is the most likely cause? |
IMD with secondary dysmorphism |
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Where are most tests for IMDs conducted? |
The Inherited Metabolic Biochemistry labs at pediatric hospitals, and later genetic laboratories |
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What results of a first line investigation might suggest an IMD? |
Hypoglycaemia, acidosis, hyperammonia, elevated LFTS, high lactate |
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What types of screening exists for neonates? |
PKU, MCAD, congenital adrenal hyperplasia, galactosaemia, CF |
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Why must a great amount of suspicion be used when diagnosing IMDs? |
They are rare enough that there are more likely causes of symptoms in neonates and young children |