INBORN-ERRORS OF THYROID-HORMONE BIOSYNTHESIS

Permanent congenital hypothyroidism in the Netherlands (incidence 1:30 00) is caused for 70-80% by a- or dysgenesis of the thyroid gland, for about 15% by dyshormonogenesis and for 10-15% by hypothalamic-pituita ry disturbances. The heredity of congenital hypothyroidism caused by d yshormonogenesis is mendelian in character and follows, with a few exc eptions. an autosomal recessive pattern, The diagnosis of these inborn errors is based on a combination of imaging studies, plasma hormone a nd thyroglobulin concentrations, and the concentration of iodide and i odinated peptides in the urine. The contribution of molecular biology is becoming an important factor in the classification of hereditary co ngenital hypothyroidism.