Identification of a New Thyroglobulin Variant: A Guanine-to-Adenine Transition Resulting in the Substitution of Arginine 2510 by Glutamine

We analyzed thyroglobulin (Tg) reverse transcription polymerase chain reaction (RT-PCR) products from three congenital goiters and three normal thyroid tissues by Taq I digestion. Tg coding sequences were amplified from position 57 to 8448 in 12 amplification fragments. A Taq I restriction fragment length polymorphism was detected in the most 3′ RT-PCR product (nt 7584 through 8448). Data from the sequence showed a G → A transition (nt 7627) causing the disappearance of the Taq I site in position 7625. It produced the substitution of arginine for a glutamine at position 2510. Afterwards, we established that the glutamine allele is present in normal unrelated individuals, with an allelic frequency of 62%. This Tg variant is thus widely represented in the human population. The available sequence information from rat and bovine Tg showed the presence, in both, of glutamine at position 2510.