Two sisters aged 4 and 8 years with convulsions and hypomagnesemia are reported from the Depts of Pediatrics and Nuclear Medicine, Univ of Nijmegen, The Netherlands. Both began to have seizures in infancy, one with fever, and both were mentally retarded. One had cerebral atrophy on CT scan. EEG showed seizure discharges with photostimulation in the older child. Phenobarbital and valproate were necessary for the control of convulsions. A low serum magnesium, accompanied by normal calcium and parathormone levels, was not related to the seizures. Urinary excretion of magnesium was elevated and urinary calcium was normal. Parents were consanguinous and had normal magnesium metabolism. An autosomal recessive mode of inheritance was presumed. 
COMMENT. The above case shows an association of low magnesium and seizures with CNS pathology. Magnesium deficiency syndromes occur in association with 1) primary hyperparathyroidism, 2) primary aldosteronism, 3) fatty diarrheas, and 4) malnutrition.