Studies on inborn errors of metabolism in Norway

Some 50 years ago, Müller described hypercholesterolemia, xanthomas, and coronary heart disease as symptoms of a genetic disorder. In the 1930s, other important discoveries concerning inborn errors of metabolism were made in Norway. Følling described phenylketonuria, and Refsum examined his first patients with heredopathia atactica polyneuritiformis (phytanic acid storage disease). Several other inborn errors of metabolism have been discovered in Norway: familial lecithin-cholesterol acyltransferase deficiency, methylmalonic acidemia, beta-methylcrotonyl-coenzyme A carboxylase deficiency, pyroglutamic aciduria, and N-acetyl aspartic aciduria. Metabolic and biochemical studies in these patients have revealed new and important metabolic pathways. Studies on patients with inborn errors not first described in Norway have also given important information on key enzymes in metabolic pathways. Thus, studies on patients with cerebrotendinous xanthomatosis and those with Zellweger's syndrome have revealed the normal metabolic route for conversion of cholesterol to bile acids. The discoveries and the clinical and biochemical research in former days were mostly good examples of serendipity combined with excellent clinical alertness. In more recent years, several of the discoveries have resulted from systematic biochemical screening of urine, plasma, or other body fluids from patients with unusual clinical syndromes.