Paediatrics: Mitochondrial disorders

Mitochondrial disorders

Disorders of mitochondrial function result in a wide of clinical problems.

• Inheritance may be either autosomal dominant/recessive or X-linked or mitochondrial (i.e. matrilineal), although most arise as de novo mutations.

• Diagnosis requires muscle biopsy, with histochemical studies, electron microscopy, and biochemical studies on isolated tissue. Presence of ‘ragged-red’ fibres in skeletal muscle biopsy is characteristic of disorders presenting with myopathy.

Leigh’s syndrome 

Relapsing acute encephalopathy; lactic acidosis; hypot-onia; seizures; +/– cardiomyopathy; +/– hepatic or renal tubular dysfunction.

Pearson’s syndrome 

Failure to thrive; lactic acidosis; sideroblastic anaemia; hypoparathyroidism; diabetes mellitus.