Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by production of autoantibodies against intracellular antigens including DNA, ribosomal P, Ro (SS-A), La (SS-B), and the spliceosome. Etiology is suspected to involve genetic and environmental factors. Evidence of genetic involvement includes: associations with HLA-DR3, HLA-DR2, Fc␥ receptors (Fc␥R) IIA and IIIA, and hereditary complement component deficiencies, as well as familial aggregation, monozygotic twin concordance >20%, s > 10, purported linkage at 1q41-42, and inbred mouse strains that consistently develop lupus. We have completed a genome scan in 94 extended multiplex pedigrees by using model-based linkage analysis. Potential [log 10 of the odds for linkage (lod) > 2.0] SLE loci have been identified at chromosomes 1q41, 1q23, and 11q14-23 in African-Americans; 14q11, 4p15, 11q25, 2q32, 19q13, 6q26-27, and 12p12-11 in EuropeanAmericans; and 1q23, 13q32, 20q13, and 1q31 in all pedigrees combined. An effect for the Fc␥RIIA candidate polymorphism) at 1q23 (lod ‫؍‬ 3.37 in African-Americans) is syntenic with linkage in a murine model of lupus. Sib-pair and multipoint nonparametric analyses also support linkage (P < 0.05) at nine loci detected by using two-point lod score analysis (lod > 2.0). Our results are consistent with the presumed complexity of genetic susceptibility to SLE and illustrate racial origin is likely to inf luence the specific nature of these genetic effects.

Reports of the incidence of ITP are few and their methodology is variable. Accurate estimates of the incidence of immune thrombocytopenic purpura (ITP) are important to understand the medical and public health impact of the disease. To critically review all published reports on the incidence of ITP in children and adults, all articles identified on the Medline database (searched January 1, 1966‐August 7, 2009) that reported data on the incidence of ITP were retrieved. Articles which directly estimated the incidence of ITP were selected for review. Eight articles reported the incidence of acute ITP in children. After review, four were determined to have the strongest estimates, based on the method of patient identification and study design. The lowest incidence estimate in these four studies was 2.2 per 105 children/year (95% confidence interval 1.9, 2.4) and the highest incidence estimate was 5.3 per 105 children/year (95% confidence interval 4.3, 6.4). Three studies reported the incidence of ITP in adults. The estimate from the article with the strongest methodology reported an incidence estimate of 3.3 per 105 adults/year. The current strongest estimate of the incidence of acute ITP in children is between 1.9 and 6.4 per 105 children/year; for adults the current strongest estimate of the incidence of ITP is 3.3 per 105 adults/year. An important limitation of these studies is that they are primarily from Europe and may not be generalizable to all regions. Am. J. Hematol. 2010. © 2009 Wiley‐Liss, Inc.