Proposal for a simplified classification of IMD based on a pathophysiological approach: A practical guide for...

Area of Science:

• Biochemistry
• Genetics
• Cell Biology

Background:

• Next-generation sequencing rapidly expands the discovery of inborn errors of metabolism (IMD).
• Existing classifications of IMD lack a unified approach, combining clinical and pathophysiological perspectives.
• A simplified classification is needed to better understand and manage the growing number of IMD.

Purpose of the Study:

• To propose a simplified classification system for inborn errors of metabolism.
• To integrate clinical diagnostic and pathophysiological approaches for IMD.
• To highlight the role of complex molecule metabolism and cell biology in IMD.

Main Methods:

• Development of a three-category classification system for IMD.
• Categorization based on small molecule disorders, complex molecule disorders, and energy metabolism disorders.
• Integration of clinical and pathophysiological insights into the classification.

Main Results:

• Small molecule disorders are divided into accumulation (intoxication) and deficiency subtypes, often treatable.
• Complex molecule disorders involve storage or deficiency, impacting fetal development and often presenting as neurodevelopmental issues.
• Energy metabolism disorders encompass defects in carriers and cytoplasmic/mitochondrial pathways.

Conclusions:

• The proposed classification provides a simplified framework for understanding IMD.
• It emphasizes the importance of complex molecule metabolism and its link to cell biology.
• This classification aids in the diagnosis and management of treatable IMD, particularly those with biomarkers.