Mild hypotonia and recurrent seizures in an 8-month-old boy: Questions.

Hypomagnesemia with secondary hypocalcemia is a rare autosomal recessive disorder which manifests in early infancy with generalized seizures, other symptoms of neuromuscular irritability, and growth disturbances. Homozygous mutations in the magnesium transporter gene, transient receptor potential melastatin 6 (TRPM6), cause the disease. Here, we present an 8-month-old Turkish boy with a novel mutation of TRPM6. The patient, son of first-degree cousins, was hospitalized because of recurrent seizures and mild hypotonia. He had seizures since the newborn period and he had been treated with phenobarbital but there was no favorable response to therapy. His past history also revealed hypocalcemia detected on the newborn period but serum magnesium levels were not studied at that time. During hospitalization, we detected hypocalcemia, hypomagnesemia, and normal parathormone levels. Abdominal ultrasound was normal. Magnesium excretion was slightly increased. Considering the consanguinity of the parents and clinical features of the patients, genetic testing of the TRPM6 gene was performed and a novel homozygous mutation was detected as c.3178A>T. He was started on magnesium and calcium supplementation and he is symptom-free for 1 year. We would like to call attention to the measurement of serum magnesium levels in children with hypocalcemic convulsions. Early and appropriate treatment with magnesium supplementation is crucial.

Carnitine and weakness in haemodialysis patients.

Weakness in haemodialysis patients has been attributed to several factors including carnitine deficiency. Malnutrition, neuropathy, uraemic myopathy and parathyroid hormone excess may all be important. Six haemodialysis patients were shown to have reduced muscle power compared with a normal population, and to be malnourished by dietary assessment, and features of their weakness were investigated. Total carnitine was normal in plasma but elevated in muscle, with an excess of esterified carnitine in both plasma and muscle and diminished free plasma carnitine. Muscle biopsy showed no features of carnitine deficiency and electromyography showed a non-specific neuropathy with additional myopathic changes in some. Dietary supplementation with L-carnitine (2 g/day) for 6 weeks in a placebo-controlled trial showed a redistribution of carnitine fractions but no subjective or objective improvement in muscle function. There was no improvement in the plasma lipid profile. The weakness of haemodialysis patients is multifactorial. We have not demonstrated total carnitine depletion in either muscle or plasma, and oral supplementation of L-carnitine has no demonstrable effect in this group.