Defective Coupling Of Iodotyrosine In Familial Goiters

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Abstract
The sequence of biochemical reactions leading to synthesis of thyroid hormones has been clearly elucidated. Defective function of any of these reactions results in goiter and frequently in hypothyroidism. Five specific biochemical defects have been delineated in patients with familial goiters1 (Fig 1). Of these, the defect in coupling of iodotyrosines to iodothyronines is infrequent. The purpose of this paper is to report two siblings who demonstrate this defect. Report of Cases Patient 1. —The patient, a 6-year-old white female, developed a goiter early in infancy which gradually increased in size. Her growth and development were normal, and no symptoms or signs of hypothyroidism were evident. She had never received thyroid extract. Two months before admission, 24-hour I131 uptake was 90%, 48-hour conversion ratio 70%, and PBI 7.8μg%. At the patient's admission, her thyroid gland was diffusely enlarged to about twice normal size. She was alert, active, and