Prenatal diagnosis of a thyroglobulin synthesis defect in goats.

A strain of goats with congenital goitre due to a thyroglobulin (Tg) synthesis defect was studied. All goats excreted low molecular weight iodinated material (LOMWIOM) in their urine, but non-goitrous goats excreted in the LOMWIOM fraction less than 5 micrograms iodine per 24 h and the goitrous ones more than 15 micrograms iodine per 24 h. Prenatal diagnosis of the Tg synthesis defect in goats is possible since non-goitrous goats pregnant with goitrous kids excrete in the LOMWIOM fraction more than 10 micrograms iodine per 24 h while non-goitrous goats pregnant with non-goitrous kids excrete 10 micrograms or less iodine per 24 h as LOMWIOM. In 24 out of 25 cases a correct diagnosis could be made in the last 47 days of pregnancy. We argue that prenatal diagnosis of analogous defects in man may also be possible, using the excretion of LOMWIOM in maternal urine as yard-stick. By means of field desorption mass spectrometry (FOMS) and high performance liquid chromatography (HPLC) monoiodohistidine was identified as the major component of the LOMWIOM fraction in the urine of goitrous goats.