[W8] Inborn Errors of Metabolism Flashcards
(27 cards)
What is an inborn error of metabolism (IEM)?
A genetically inherited disorder that disrupts normal metabolic processes.
IEMs can lead to a variety of health issues depending on the specific metabolic pathway affected.
What is the most common type of defective protein in IEMs?
Enzymes.
Enzyme deficiencies can lead to an accumulation of substrates or toxic intermediates.
How are most IEMs inherited?
Autosomal recessive.
This means that two copies of the mutated gene must be present for the disorder to manifest.
Who is affected in X-linked recessive IEMs?
Males, females are carriers.
Males are typically more severely affected due to having only one X chromosome.
Name 3 ways IEMs cause disease.
- Substrate accumulation
- Toxic intermediates
- Failed transport
Each mechanism can lead to different clinical manifestations.
What are classic symptoms of IEMs in infants?
- Poor feeding
- Vomiting
- Lethargy
These symptoms can be indicative of various metabolic disorders.
What are symptoms in older children with IEMs?
- Developmental delay
- Failure to thrive
Early diagnosis and management are crucial for better outcomes.
What enzyme is missing in MCADD?
Medium-chain acyl-CoA dehydrogenase.
This deficiency impairs fatty acid metabolism, leading to hypoketotic hypoglycemia.
What causes symptoms in PKU?
Accumulation of phenylalanine.
High levels of phenylalanine can lead to intellectual disability if untreated.
What is the treatment for GSD Type I?
Frequent feeding and corn starch.
This helps maintain blood glucose levels and prevent hypoglycemia.
What enzyme defect causes Tyrosinaemia Type 1?
Tyrosine catabolism enzyme deficiency.
This can lead to severe liver and kidney damage if left untreated.
What sample is used to detect amino acid disorders?
Plasma amino acids or dried blood spot.
These samples are analyzed to identify abnormal levels of amino acids.
What indicates a urea cycle disorder?
High plasma ammonia, especially with neurological symptoms.
Elevated ammonia levels can be life-threatening and require immediate treatment.
What test is key in organic acid disorders?
Urine organic acids.
This test helps identify the presence of specific organic acids associated with metabolic disorders.
What smell is associated with PKU?
Musty.
This characteristic odor is due to the accumulation of phenylalanine.
What disorder causes ‘sweaty feet’ odour?
Isovaleric acidaemia.
The odor is caused by the accumulation of isovaleric acid.
What smell is linked to MSUD?
Maple syrup.
This is due to the presence of branched-chain amino acids in the urine.
Key metabolic feature of MCADD?
Inability to oxidise medium-chain fatty acids
Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) affects the ability to break down certain fats for energy.
Lab findings in MCADD?
Hypoglycaemia, low ketones, high free fatty acids
These lab findings are due to the inability to utilize medium-chain fatty acids effectively.
Enzyme deficiency in GSD I?
Glucose-6-phosphatase
This enzyme is crucial for gluconeogenesis and glycogenolysis, and its deficiency leads to energy metabolism issues.
Key features of GSD I?
Hypoglycaemia, hepatomegaly, seizures, lactic acidosis
These symptoms arise due to the accumulation of glycogen and its inability to be converted into glucose.
Enzyme deficiency in PKU?
Phenylalanine hydroxylase (PAH)
This enzyme is necessary for the metabolism of phenylalanine to tyrosine, and its deficiency leads to toxic accumulation.
