Prenatal Diagnosis of Disorders of Carbohydrate Metabolism
Inherited disorders of carbohydrate metabolism result from defects in enzymes or transport proteins involved in glycolysis, gluconeogenesis, or glycogen metabolism. The carbohydrates to be discussed include three monosaccharides: glucose, galactose, and fructose. This chapter deals with the common carbohydrate disorders encountered in the population. Discussion of each disorder includes the pathophysiology of the disease, clinical manifestations, treatments, genetic information, carrier detection, and prenatal testing. Glycogen storage diseases (GSD) are inherited disorders that affect glycogen metabolism. The treatment of type I GSD seeks to maintain normoglycemia, which corrects most of the metabolic abnormalities and reduces the morbidity associated with this disease. Type II GSD is caused by a deficiency of lysosomal acid a-glucosidase, an enzyme responsible for the degradation of glycogen in the lysosomes. Type III GSD is caused by a deficiency of glycogen debrancher enzyme activity. Galactosemia is a general term used to describe three distinct disorders of galactose metabolism.
