Linkage of familial euthyroid goiter to the multinodular goiter-1 locus and exclusion of the candidate genes thyroglobulin, thyroperoxidase, and Na+/I- symporter
S. Neumann et al., Linkage of familial euthyroid goiter to the multinodular goiter-1 locus and exclusion of the candidate genes thyroglobulin, thyroperoxidase, and Na+/I- symporter, J CLIN END, 84(10), 1999, pp. 3750-3756
Iodine deficiency is the most important etiological factor for euthyroid en
demic goiter. However, family and twin pair studies also indicate a genetic
predisposition for euthyroid simple goiter. In hypothyroid goiters several
molecular defects in the thyroglobulin (TG), thyroperoxidase (TPO), and Na
+/I- symporter (NIS) genes have been identified. The TSH receptor with its
central role for thyroid function and growth is also a strong candidate gen
e. Therefore, we investigated a proposita with a relapsing euthyroid goiter
and her family, in which several members underwent thyroidectomy for euthy
roid goiter. Sequence analysis of the complementary DNA (cDNA) of the TPO a
nd TSH receptor genes revealed several previously reported polymorphisms. A
s it is not possible to exclude a functional relevance for all polymorphism
s, we opted for linkage analysis with microsatellite markers to investigate
whether the candidate genes are involved in the pathogenesis of euthyroid
goiter. The markers for the genes TG, TPO, and NIS gave two-point and multi
point logarithm of odds score analysis scores that were negative or below 1
for all assumed recombination fractions. As no significant evidence of lin
kage was found, we conclude that these candidate genes can be excluded as a
major cause of the euthyroid goiters in this family. In contrast, we have
found evidence for linkage of familial euthyroid goiter to the recently ide
ntified locus for familial multinodular nontoxic goiter (MNG-1) on chromoso
me 14q. The haplotype cosegregates clearly with familial euthyroid goiter.
Our results provide the first confirmation for MNG-1 as a locus for nontoxi
c goiter.