Subjects with PCOS defined by IM/HA are the most severely affected women on the basis of androgen levels, ovarian volumes, and insulin levels. Their higher body mass index partially accounts for the increased insulin levels, suggesting that weight gain exacerbates the symptoms of PCOS.

We replicated one of the five Chinese PCOS association signals, represented by rs10986105 and rs10818854 on 9q33, in individuals of European ancestry. Examination of the subjects meeting at least one of the Rotterdam criteria for PCOS suggests that the variant may be involved in the hyperandrogenism and possibly the irregular menses of PCOS.

Primary immunodeficiency diseases (PID) are a genetically heterogenous group of >150 disorders that affect distinct components of the innate and adaptive immune system and are often associated with autoimmune diseases. We describe PID affecting T‐regulatory cells, complement and B cells or their products and discuss the possibility of a cause–effect relationship. The high concordance of T‐regulatory cell defects to organ‐specific autoimmune disease implies an obligatory role of these cells in maintaining tolerance to epithelial and endocrine tissues; the absence of central nervous system involvement may reflect immunological privilege. Congenital defects in C1q, C1r/s and C4 are strongly associated with systemic lupus erythematosus (SLE), and this pattern along with laboratory evidence suggests a major importance of classical pathway activity in safe elimination of immune complexes and prevention of immune complex disease (ICD). It is debatable whether this ICD is to be regarded as an autoimmune disease (resulting from a breakdown of immunological ignorance to antigens that are normally hidden), as autoantibodies may be absent, and tissue damage because of deposition of immune complexes could account for all of the pathology observed. Evidence for a causative link between primary antibody deficiencies and autoimmune disease is much less compelling and may in fact involve a common genetic background. However, arguments have also been made in favour of the notion that an intense antigen load as a result of recurrent or persistent infections may affect either tolerance or ignorance, e.g. by molecular mimicry or the presence of superantigens. Similar immunological mechanisms might account for the vast majority of autoimmune diseases.