Inherited metabolic diseases

Also called inborn errors of metabolism, these are heritable (genetic) disorders of biochemistry. Examples include albinism, cystinuria (a cause of kidney stones), phenylketonuria (PKU), and some forms of gout, sun sensitivity, and thyroid disease. These are only a very few of the hundreds of known inborn errors of metabolism. Advances in the diagnosis and treatment of inborn errors of metabolism have improved the outlook for many of these conditions so that early diagnosis, if possible in infancy, can be helpful. Many of the inborn errors of metabolism in young infants cause symptoms such as sluggishness (lethargy), poor feeding, apnea (stopping breathing) or tachypnea (fast breathing), and recurrent vomiting. Any infants, particularly full-term infants, with these findings should be seen and checked immediately by a doctor. Laboratory testing for metabolic disorders is done in children who are possible candidates for inborn errors of metabolism. This testing might, for example, include: Blood sugar: Hypoglycemia (low blood sugar) is the predominant finding in a number of inborn errors of metabolism. Blood tests for jaundice (yellowing) or other evidence of liver disease: This is a sign of another important group of inborn errors of metabolism. Specific patterns of birth defects characterize yet another group of inherited metabolic disorders. The great number, complexity, and varied features of the inborn errors of metabolism require a book, a large book, to consider each one of them in any detail. While most of these disorders are individually rare, together they represent a major source of human disease and suffering. The term "inborn of metabolism" was coined in 1908 by the British physician and pioneer in medical genetics Sir Archibald Garrod (whose father also discovered a key abnormality in metabolism: the presence of uric acid in the urine of people with gout).