Klinefelter's syndrome (47,XXY) among men with systemic lupus erythematosus

Aim: To determine the rate of Klinefelter's syndrome among men with systemic lupus erythematosus (SLE), and to determine whether the manifestations of SLE in these men are different from that seen in 46,XY men. Methods: A total of 276 men with SLE underwent a real-time PCR procedure to screen for more than one X chromosome. Those with results consistent with two X chromosomes were further characterized by karyotype and FISH. Clinical manifestations of SLE were determined by interview, questionnaire and medical chart review. Each man with Klinefelter's and SLE was matched to four 46,XY men with SLE. Rates of SLE manifestations were compared with chi-square analyses. Results: We found seven of the 286 men with SLE had Klinefelter's syndrome. Four of these seven were nonmosaic 47,XXY, while two were mosaic 46,XY/47,XXY and one was 46,XX/47,XXY. The men with 47,XXY did not have severe manifestations of SLE including no proliferative renal disease, neurological disease, thrombocytopenia, autoimmune haemolytic anaemia, discoid skin disease or anti-RNP/Sm. Conclusion: 47,XXY is found in excess among men with SLE. Men commonly have SLE that is more severe than that found among women, but the 47,XXY men had less severe SLE than other men.