Factor H autoantibodies have been reported in approximately 10% of patients with atypical hemolytic uremic syndrome (aHUS) and are associated with deficiency of factor H-related proteins 1 and 3. In this study we examined the prevalence of factor H autoantibodies in the Newcastle cohort of aHUS patients, determined whether the presence of such autoantibodies is always associated with deficiency of factor H-related proteins 1 and 3, and examined whether such patients have additional susceptibility factors and/or mutations in the genes encoding complement regulator/activators. We screened 142 patients with aHUS and found factor H autoantibodies in 13 individuals (age 1-11 years). The presence of the autoantibodies was confirmed by Western blotting. By using multiplex ligation-dependent probe amplification we measured complement factor H-related (CFHR)1 and CFHR3 copy number. In 10 of the 13 patients there were 0 copies of CFHR1, and in 3 patients there were 2. In 3 of the patients with 0 copies of CFHR1 there was 1 copy of CFHR3, and these individuals exhibited a novel deletion incorporating CFHR1 and CFHR4. In 5 patients mutations were identified: 1 in CFH, 1 in CFI, 1 in CD46, and 2 in C3. The latter observation emphasizes that multiple concurrent factors may be necessary in individual patients for disease manifestation. (Blood. 2010;115:379-387)

In this study we have used multiplex ligation-dependent probe amplification (MLPA) to measure the copy number of CFHR3 and CFHR1 in DNA samples from 238 individuals from the UK and 439 individuals from the HGDP-CEPH Human Genome Diversity Cell Line Panel. We have then calculated the allele frequency and frequency of homozygosity for the copy number polymorphism represented by the CFHR3/CFHR1 deletion. There was a highly significant difference between geographical locations in both the allele frequency (X2 = 127.7, DF = 11, P-value = 4.97x10-22) and frequency of homozygosity (X2 = 142.3, DF = 22, P-value = 1.33x10-19). The highest frequency for the deleted allele (54.7%) was seen in DNA samples from Nigeria and the lowest (0%) in samples from South America and Japan. The observed frequencies in conjunction with the known association of the deletion with AMD, SLE and IgA nephropathy is in keeping with differences in the prevalence of these diseases in African and European Americans. This emphasises the importance of identifying copy number polymorphism in disease.

Leukocytes including monocyte/macrophages, granulocytes, and T lymphocytes were localized in the corpus luteum (CL) of pregnant and pseudopregnant rats using monoclonal antibodies reactive with lineage-specific antigens. Neutrophilic granulocytes and monocytes/macrophages were found to be the most abundant leukocyte populations in the CL during both pregnancy and pseudopregnancy. The density of neutrophilic granulocytes (MCA 149-reactive cells) increased approximately 2-fold after mating, to peak on Day 9 of pseudopregnancy (214 +/- 13 positive cells/0.125 mm2 grid area) and Day 10 of pregnancy (216 +/- 12/grid area), and then declined in later stages of CL life. In pregnant rats, monocytes/macrophages positive for the monoclonal antibody ED1 were most numerous during early CL life when they were approximately 6-fold more plentiful than at luteolysis (153 +/- 14/grid area at Day 5 vs. 25 +/- 2 at 2 days postpartum). In pseudopregnant rats, the density of ED1-positive cells declined approximately 5-fold during the life span of the CL (124 +/- 17/grid area at Day 2 vs. 20 +/- 2 at Day 13) prior to a second, somewhat lesser peak at luteal regression (84 +/- 12 at Day 15). Fewer monocyte/macrophages within the CL were found to express antigen reactive with the monoclonal antibody ED2, which is characteristically a marker for tissue-macrophages (7% of the density of ED1-positive cells at Day 5 in the pregnant group and 13% at Day 2 in the pseudopregnant group); and while there was an approximately 60% reduction in the number of ED2-positive cells during pregnancy, these cells were found not to fluctuate significantly in number over the course of CL life in pseudopregnant animals.(ABSTRACT TRUNCATED AT 250 WORDS)

No abstract

Summary Background and objectives Atypical hemolytic uremic syndrome is a disease associated with mutations in the genes encoding the complement regulators factors H and I. In addition, factor H autoantibodies have been reported in ∼10% of patients with atypical hemolytic uremic syndrome. This study searched for the presence of factor I autoantibodies in atypical hemolytic uremic syndrome. Design, setting, participants, & measurements This study screened 175 atypical hemolytic uremic syndrome patients for factor I autoantibodies using ELISA with confirmatory Western blotting. Functional studies using purified immunoglobulin from one patient were subsequently undertaken. Results Factor I autoantibodies were detected in three patients. In one patient with a high titer of autoantibody, the titer was tracked over time and was found to have no association with disease activity. This study found evidence of an immune complex of antibody and factor I in this patient, but purified IgG, isolated from current serum samples, had only a minor effect on fluid phase and cell surface complement regulation. Genetic analysis of the three patients with factor I autoantibodies revealed that they had two copies of the genes encoding factor H–related proteins 1 and 3 and therefore, did not have a deletion commonly associated with factor H autoantibodies in atypical hemolytic uremic syndrome. Two patients, however, had functionally significant mutations in complement factor H. Conclusions These findings reinforce the concept of multiple concurrent risk factors being associated with atypical hemolytic uremic syndrome but question whether autoantibodies per se predispose to atypical hemolytic uremic syndrome.

Summary. Platelet membrane glycoprotein polymorphisms are candidate risk factors for thrombosis, but epidemiological data are conflicting. Thus, demonstration of a genotype-dependent alteration in function is desirable to resolve these inconsistencies. We investigated in vivo platelet activation in acute thrombosis and related this to platelet genotype. Frequencies of the 1b and 2b alleles of the HPA 1a/1b and HPA 2a/2b platelet glycoprotein polymorphisms were determined in 150 (52 men/98 women, mean age 58´3 years) patients with atherothrombotic stroke, and the influence of genotype on markers of platelet activation was assessed. Platelet P-selectin (CD62P) expression and fibrinogen binding was measured using whole blood flow cytometry within 24 h of stroke and 3 months later in 77 patients who provided a repeat blood sample. Results were compared with matched controls. Neither the 1b allele [allele frequency 0´11 vs. 0´13, odds ratio (OR) confidence interval (CI) 0´8 (0´5±1´3)] nor the 2b allele [0´09 vs. 0´07, OR (CI) 1´4 (0´8±2´4)] was significantly over-represented in patients. Increased numbers of activated platelets were found following stroke (acute mean P-selectin expression 0´64% vs. control 0´35%, P , 0´001; acute mean fibrinogen binding 1´6% vs. control 0´9%, P , 0´001). Activation persisted in the convalescent phase (P , 0´001 and P 0´005 vs. controls for P-selectin and fibrinogen respectively). Expression of P-selectin and fibrinogen was not influenced by either the HPA 1a/1b genotype (P . 0´95 for each marker, Scheffe's test) or the 2a/2b genotype (P . 0´95 for each). Although persisting platelet activation is seen in atherothrombotic stroke, it is independent of HPA 1a/1b and 2a/2b genotypes. These data suggest an underlying prothrombotic state, but do not support the polymorphisms studied as risk factors for thrombotic stroke in this population.

The level of factor H autoantibodies is lower in AMD patients than in age-matched control subjects.

End-stage renal disease (ESRD) presenting in a familial autosomal dominant pattern points to an underlying monogenic cause. Nail-patella syndrome (NPS) is an autosomal dominant disorder that may lead to ESRD caused by mutations in the transcription factor LMX1B. Renal-limited forms of this disease, termed nail-patella-like renal disease (NPLRD), and LMX1B nephropathy have recently been described. We report a large family, from the North East of England, with seven affected members with varying phenotypes of renal disease, ranging from ESRD at 28 years of age to microscopic haematuria and proteinuria and relatively preserved renal function. In this family, there were no extra-renal manifestations to suggest NPS. Genome-wide linkage studies and inheritance by descent (IBD) suggested disease loci on Chromosome 1 and 9. Whole exome sequencing (WES) analysis identified a novel sequence variant (p.R249Q) in the LMX1B gene in each of the three samples submitted, which was confirmed using Sanger sequencing. The variant segregated with the disease in all affected individuals. In silico modelling revealed that R249 is putatively located in close proximity to the DNA phosphoskeleton, supporting a role for this residue in the interaction between the LMX1B homeodomain and its target DNA. WES and analysis of potential target genes, including CD2AP, NPHS2, COL4A3, COL4A4 and COL4A5, did not reveal any co-inherited pathogenic variants. In conclusion, we confirm a novel LMX1B mutation in a large family with an autosomal dominant pattern of nephropathy. This report confirms that LMX1B mutations may cause a glomerulopathy without extra-renal manifestations. A molecular genetic diagnosis of LMX1B nephropathy thus provides a definitive diagnosis, prevents the need for renal biopsies and allows at risk family members to be screened.