Rheumatoid arthritis in thyroid disease positive and negative same-sexed sibships

A total of 249 rheumatoid arthritis (RA) same-sexed sibships were clinically documented, HLA-typed and had auto-antibody screens performed. Sibships with a history of thyroid disease (TD) or significant thyroid antibodies were categorized as 'thyroid' sibships and the rest 'non-thyroid'. TD was more common in the female RA sibships than controls, particularly in the RA probands. The presence of thyroid microsomal antibody, but not thyroglobulin antibody, was significantly higher in all members of the female sibships, and in the probands and non-RA siblings of the male sibships. Comparing the thyroid and non-thyroid sibships, there was no significant difference in the distribution of HLA haplotypes in RA-RA sibling pairs, and HLA-DR status, clinical or immunological characteristics of the probands. These data do not support the concept that predisposition to RA in thyroid sibships might be non-DR4 or non-HLA linked.