A substantial number of genetically determined biochemical disorders in infants and young children produce mental deficiency and serious ill health in early life. If these diseases are detected promptly, effective therapy can be instituted to prevent the development of mental defect, or, where no treatment is presently available, the parents can be given appropriate genetic counselling so that the birth of further affected children can be prevented.Eight simple urine screening tests are described which have proved useful in the early detection of metabolic disorders in apparently healthy infants. These tests can easily be performed by a physician or nurse without special training or elaborate equipment. The attention of general practitioners, pediatricians and public health physicians is directed to the real possibilities for preventing some forms of mental deficiency through the routine use of screening tests on urine and on blood.

MULTIPLE SCLEROSIS continues to elude widespread efforts to clarify its etiology. No infectious agent has been implicated, and no specific metabolic error has been demonstrated. Although evidence suggests that some demyelinating diseases may be due to unusual antigen antibody reactions, conclusive demonstration that multiple sclerosis involves any type of immune response is lacking. Epidemiologic and genetic studies have provided certain clues which imply that the etiology may be multifactorial. The disease occurs more commonly in women than in men,l and its much greater frequency among relatives of patients than in the general population2 suggests hereditary factors. That its prevalence increases at higher latitudes in both the northern and southern hemispheres is accepted.3-5 Several investigators have suggested that an abnormality in the metabolism of a trace metal or trace metal poisoning from environmental sources might play a part in the etiology of multiple sclerosis. The genetically determined abnormality in Wilson’s disease results in damage to parts of the central nervous system as a result of deposition of excessive amounts of copper, a metal which is required in trace amounts by various enzyme systems. Other neurological diseases conceivably might result from analogous metabolic errors involving other essential trace metals. Neurological disease is produced by excessive ingestion or inhalation of lead or mercury which seems to play no physiological role in mammalian metabolism. Copper deficiency in pregnant sheep, the result of grazing on pastures growing on copper-deficient soils, causes a rapidly fatal demyelinating disease of lambs, a condition known as swayback in Great Britain and as enzootic ataxia in Australia. The close resemblance of the pathological changes found in the brain in swayback to those seen in multiple sclerosis in man prompted Mandelbrote and his co-workers6 to investigate copper metabolism in multiple sclerosis. They found no significant difference in urinary copper excretion or blood or liver copper concentrations of healthy subjects and patients with multiple sclerosis. Campbell and associates7 found an unusually high lead content in the soil of an English village with a high incidence of multiple sclerosis. They also reported that the lead content of unfilled teeth was greater in patients with multiple sclerosis than in healthy individuals. On the other hand, Kurlands pointed out that multiple sclerosis is relatively uncommon in important lead-producing countries, such as Spain and Mexico, and that in the northern United States and Canada, where the prevalence of multiple sclerosis is relatively high, swayback of lambs does not occur. Certain epidemiologic studies suggest that the mineral content of soil and, in turn, of food and drinking water, might play some part in the etiology of multiple sclerosis. Prevalence of the disease has been reported to be ten times as great in the Orkney and Shetland Islands as in the Faroe Islands.9 These 2 isolated areas are situated at high latitudes, have similar climates, and are peopled by genetically similar stocks. Their geologic formations, however, differ widely. The Orkneys and Shetlands

Rats made artificially phenylketonuria during fetal or early neonatal life by administration of large amounts of phenylalanine showed no defect in learning ability when tested later for capacity to acquire visual discrimination. Administration of large amounts of 5-HTP failed to correct the low brain serotonin concentrations characteristic of artificial phenylketonuria, The results of this investigation do not provide support for the theory that a serotonin deficiency in brain during infancy causes the mental defect characteristic of human phenylketonuria. In addition, it appears unlikely that the rat is a suitable experimental animal for exploring the exact mechanism of the mental defect of phenylketonuria in man.