Thyroxine-binding prealbumin gene polymorphism: a population study

The human thyroxine-binding prealbumin (TBPA) gene was examined for restriction fragment length polymorphism (RFLP) in normal subjects and a subject with euthyroid hyperthyroxinaemia, due to increased thyroxine binding by TBPA, using 16 restriction enzymes. Only Taq I and Msp I were shown to detect RFLPs. In a male of the normal population and one of his daughters, an additional Taq I site was found in the 3'-flanking region of the TBPA gene. The RFLP in a subject with euthyroid hyperthyroxinaemia was due to the deletion of a MspI site. All three subjects with RFLPs were heterozygous.