There are reports suggesting that people with Klinefelter’s syndrome (KS) may be at increased
risk of some autoimmune diseases, but the evidence is not substantial. We wanted to add to
the evidence by systematically assessing the risk of autoimmune diseases in a national cohort
of people with KS. We selected records of all people with KS in a record-linked dataset of all
hospital day cases and inpatient admissions in England, 1999–2011; and we followed them up
by electronic record linkage to identify the occurrence of autoimmune diseases.
We compared
their occurrence in the KS cohort with a control cohort, studied in the same way, and expressed
the results as rate ratios (RR). Of 30 autoimmune diseases studied in people with KS, there
were significantly increased risks of seven–Addison’s disease (RR 11.7, 95% confidence interval
2.4–34.4), diabetes mellitus type 1 (6.1, 4.4–8.3), multiple sclerosis (4.3, 1.2–11.0), acquired
hypothyroidism (2.7, 1.8–4.0), rheumatoid arthritis (3.3, 2.0–5.2), Sjogren’s syndrome (19.3,
4.0–57.0) and systemic lupus erythematosus (18.1, 2.2–65.6). We concluded that people with KS
have increased risk of some autoimmune diseases, particularly those that are femalepredominant.
The increased risk of autoimmune diseases associated with the XXY karyotype
may hold clues to the pathogenesis of some aspects of autoimmunity
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