Genetic and Metabolic MedicineTier 2Topic

Structure and function of human cells, genes, DNA, RNA, and proteins

Overview

Cellular structure and organelle function underpin the mechanisms of many inherited metabolic and genetic disorders - defects localise to specific organelles (mitochondria, lysosomes, peroxisomes, the nucleus itself), each producing a characteristic disease pattern
Investigation of suspected metabolic/genetic disease often specifically targets the organelle system implicated by the clinical phenotype

Organelles and their diseases

Organelle	Function	Disease example if defective
Mitochondria	Oxidative phosphorylation/ATP production	Mitochondrial disorders - high-energy-demand organs (brain, muscle, heart) affected preferentially
Lysosome	Intracellular degradation of macromolecules	Lysosomal storage diseases (Fabry, Gaucher, MPS) - progressive substrate accumulation
Peroxisome	Fatty acid oxidation, bile acid synthesis	Peroxisomal disorders (e.g. Zellweger spectrum)
Nucleus	DNA repair, transcription	DNA repair disorders (e.g. xeroderma pigmentosum), imprinting disorders

Investigation strategy

Investigation strategy is guided by the organelle system implicated by the clinical pattern: enzyme activity assays (for lysosomal/peroxisomal disorders), mitochondrial respiratory chain studies/muscle biopsy (for suspected mitochondrial disease), and molecular/genetic testing targeting the relevant gene(s), often used in combination rather than any single test alone

Management

Confirmed organelle-specific diagnoses guide condition-specific management (enzyme replacement for several lysosomal storage diseases, mitochondrial cocktail/supportive therapy for mitochondrial disease, dietary modification for some peroxisomal/metabolic disorders)

Disease groups

Mitochondrial disorders, lysosomal storage diseases (Fabry, Gaucher), peroxisomal disorders, DNA repair disorders
Understanding which organelle system is implicated by the clinical phenotype (which organs are affected, and how) directs a far more targeted, efficient investigation strategy than a broad, undirected genetic testing approach

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