Chapter 11 Autoimmunity in Turner's, Down's, and Klinefelter's Syndromes

This review opens with descriptions of the range of clinical features observed in Turner's syndrome, Down's syndrome, and Klinefelter's syndrome. This is followed by an account of the disturbances of chromosomal number and structure, and the underlying mechanisms leading to the various karyotypes are outlined. Next follows an overview of the mechanisms of autoimmune disease and risk factors including genes and environmental influences, such as stress and infection. The evidence for the nature, prevalence, and clinical consequences of autoimmune disorders in Turner's syndrome, Klinefelter's syndrome, and Down's syndrome is then reviewed, emphasising the similarities and differences between them. Finally potential mechanisms underlying autoimmunity in chromosomal disorders are examined including sex steroids, parental autoimmunity, X-monosomy, X chromosome inactivation, and the possible importance of skewing of X-inactivation. The special issues addressed relating to Down's syndrome include evidence for premature ageing of the immune system and over-expression of genes on chromosome 21.