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An 8-year-old Chinese girl who was noted to have feeding difficulty and poor weight gain since her infancy. Her motor development was delayed with sitting at 1-year-old and walking independently at 2-year-old. She visited our OPD when she was 8. Physically, she was thin and slender. Her height and weight were below the 10th and 3rd percentile. Her face was elongated with high arched palate. Neurologically, she had waddling gate with marked proximal muscle weakness. Her cranial nerves and sensation remained intact. Laboratory tests including blood routine, liver function, renal function, electrolytes, NCV and cardiac echo all were within normal limits. The EMG showed myopathic pattern. A fresh-frozen muscle biopsy stained with the modified Gomori trichrome, processed by histochemistry and electronmicroscopic examination showed typical nemaline rods with predominance of type 1 muscle fibers. She was then diagnosed to have nemaline myopathy.

Leigh's disease is one of the mitochondrial encephalomyopathies. This article presents a 7-month-old baby boy who had been well-being since birth until 6 months of age when episodic downward gaze of both eyes with limitation of horizontal eye movement were noted. This episode of cranial nerve palsies lasted about 4-5 days and subsided spontaneously. The second attack was noted one month later, to be associated with hypotonia and truncal ataxia. Episodic hyperventilation with resultant gasping and myoclonus was noted at the third attack but spontaneous respiration resumed soon with persistent ophthalmoplegia and truncal ataxia. Lumbar puncture, brain MRI, amino acid assay and cardiac echo all showed negative finding. The oral glucose lactate stimulation test revealed an elevation of lactic acid, brain stem evoked potential indicated bilateral obscure 4th and 5th waves, and muscle biopsy showed ragged red fibres with aggregation of structurally abnormal mitochondria noted under electron microscope. Coenzyme Q, thiamine and carnitine had been given before biochemical study; however, the neurological symptoms did not show any improvement. Biochemical study finally revealed normal respiratory chain enzymes including NADH-coenzyme Q reductase, succinate coenzyme Q reductase and cytochrome c oxidase while other enzymes were technically unavailable for study. Unfortunately the patient died at 18-month-old due to respiratory failure.

Congenital fiber type disproportion (CFTD) is described clinically as muscle weakness and hypotonia with delayed motor development, usually from infancy. Muscle biopsy reveals that type 1 fibers predominate and smaller than type 2 fibers by a margin greater than 12% of the diameter of the type 2 fibers. There are no other subcellular abnormalities, and generally prognosis is good. The CFTD case is a six-month-old girl who manifested clinically as a floppy infant. A biopsied specimen from the left biceps brachii muscle revealed type 1 fiber predominance and hypoplasia with an increased number of undifferentiated type 2C fibers. Electromyogram, nerve conduction velocity and serum creatine kinase level were normal. The child learned to walk without assistance at 1 year 7 month old. Now 2-years and 10-months old, she can climb stairs without difficulty, although she cannot run fast.