Aggregation of thyroid autoantibodies in twins from opposite-sex pairs suggests that microchimerism may play a role in the early stages of thyroid autoimmunity.
BACKGROUND
Microchimerism is the presence of small populations of cells from one individual in another genetically distinct individual. This phenomenon can arise from pregnancy, blood transfusion, or bidirectional cell trafficking between twins in utero. Microchimerism has recently been proposed to play a role in the pathogenesis of thyroid autoimmunity. In that case, twins from opposite-sex pairs (OS) should have an increased risk of thyroid autoantibodies (TA).


OBJECTIVE
The aim of the study was to compare the frequency of TA in twin individuals from OS and monozygotic (MZ) twin pairs.


METHODS
This was a case-control study of 240 individuals (120 females and 120 males) from OS twin pairs (cases) and 568 control individuals from MZ pairs (284 females and 284 males).


METHODS
Antibodies toward thyroid peroxidase (TPOAb), thyroglobulin (TgAb), and the TSH receptor (TSHRAb) were measured and considered positive if greater than 60 U/ml, greater than 60 U/ml, and greater than 1.0 U/liter, respectively.


RESULTS
The frequency of TPOAb, TgAb, and TSHRAb among female cases was 15.0, 5.0, and 4.2%, respectively, which was higher than the corresponding prevalences in the female control population: 7.4% (P = 0.018), 1.1% (P = 0.023), and 0.7% (P = 0.026), respectively. However, when corrected for the number of phenotypes studied (TPOAb, TgAb, TSHRAb, and any thyroid antibody), the association remained significant only in the combined group, P(corrected) = 0.012. Essentially similar results were obtained in males.


CONCLUSIONS
Both female and male twins from OS pairs, as opposed to MZ pairs, have an increased frequency of TA, indicating a potential role of microchimerism in developing TA.
Brix
Thomas Heiberg
TH
Department of Endocrinology and Metabolism, Odense University Hospital, 5000 Odense C, Denmark. thomas.brix@ouh
Hansen
Pia Skov
PS
Kyvik
Kirsten Ohm
KO
Hegedüs
Laszlo
L
D000293:Adolescent; D000328:Adult; D001323:Autoantibodies / Q000097:blood; D015551:Autoimmunity; D001724:Birth Weight; D046528:Chimerism / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007453:Iodide Peroxidase / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011989:Receptors, Thyrotropin / Q000276:immunology; D013954:Thyroglobulin / Q000276:immunology; D013961:Thyroid Gland / Q000276:immunology*; D014429:Twins, Dizygotic / Q000235:genetics* / Q000276:immunology; D055815:Young Adult
D001323:Autoantibodies; D011989:Receptors, Thyrotropin; D013954:Thyroglobulin; D007453:Iodide Peroxidase