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Cardiomyopathy: When is it an Inborn Error of Metabolism? By NAMA

13 Mar 2024
Venue: Metro Toronto Convention Center
Meeting Room: 717 AB
Biochemical/Metabolic and Therapeutics
  • Accredited:
    • Accredited
  • Primary Categories:
    • Metabolic Genetics
  • Secondary Categories:
    • Metabolic Genetics
  • Level of Learner:
    • Intermediate
Metabolism refers to a network of biochemical reactions that allow continuous exchanges of energy and molecules, maintaining homeostasis. Biochemical and clinical consequences from the defects of small molecule metabolism pathways- involving protein, carbohydrate and fatty acid- have been well recognized. More recently, defects in the glycosylation process and complex molecule metabolisms have been recognized as evolving disease entities. Metabolic derangement of these inborn errors of metabolism (IEM) may not necessarily be immediately noticed unless specifically suspected, while biochemical assays can expedite the diagnosis without the need to perform extensive molecular testing. We aim to raise awareness of IEM and their presentation, diagnostic work-up and therapeutic updates among general geneticists by using cardiomyopathy as the common theme.

Session #1 – defects in protein metabolism presenting as cardiomyopathy

In most amino acid metabolism, deamination leaves ammonia and an organic acid. Depending on the defect in the pathway, amino acids, organic acids or ammonia and other downstream metabolites accumulate in the blood and urine. Plasma amino acids and urine organic acid analysis can show characteristic patterns in this group. In propionic acidemia, the accumulation of toxic compounds leads to mitochondrial dysfunction, causing cardiomyopathy.

Session #2 – defects in fatty acid metabolism presenting as cardiomyopathy

Fatty acids are beta-oxidized to generate energy to support gluconeogenesis. Defects in the beta-oxidation cannot support gluconeogenesis and free acetyl-CoA production during prolonged fasting and cause hypoketotic hypoglycemia. Upstream defects lead to the accumulation of long-chain fatty acid intermediates and secondary mitochondrial dysfunction leading to cardiomyopathy.

Session #3 – congenital disorders of glycosylation (CDG) presenting as cardiomyopathy

Defects in the synthesis and attachment of glycoprotein and glycolipid glycans lead to CDGs, a genetically heterogeneous group of disorders causing systemic symptoms. Complex interactions between abnormal glycoprotein formation and various cellular processes in cardiac muscle cells can cause cardiomyopathy.

Session #4 - Diagnostic Approach to Cardiomyopathy

An organized approach is presented for considering a metabolic etiology in a patient who presents with cardiomyopathy. The information that can discern the various diagnoses helps to form the questions a clinician needs to ponder when working up a case.

Learning Objectives

  1. Recognize presentations of cardiomyopathy due to inborn errors of metabolism
  2. Explain biochemical pathways leading to cardiomyopathy
  3. Recognize mechanisms of treatable inborn errors presenting as cardiomyopathy
  4. Summarize biochemical pathways leading to each presentation of inborn errors of metabolism