Variation in CFHR3 determines susceptibility to meningococcal disease by controlling factor H concentrations.

Neisseria meningitidis protects itself from complement-mediated killing by binding complement factor H (FH). Previous studies associated susceptibility to meningococcal disease (MD) with variation in CFH, but the causal variants and underlying mechanism remained unknown. Here we attempted to define the association more accurately by sequencing the CFH-CFHR locus and imputing missing genotypes in previously obtained GWAS datasets of MD-affected individuals of European ancestry and matched controls. We identified a CFHR3 SNP that provides protection from MD (rs75703017, p value = 1.1 × 10-16) by decreasing the concentration of FH in the blood (p value = 1.4 × 10-11). We subsequently used dual-luciferase studies and CRISPR gene editing to establish that deletion of rs75703017 increased FH expression in hepatocyte by preventing promotor inhibition. Our data suggest that reduced concentrations of FH in the blood confer protection from MD; with reduced access to FH, N. meningitidis is less able to shield itself from complement-mediated killing.

Common haplotypes at the CFH locus and low-frequency variants in CFHR2 and CFHR5 associate with systemic FHR concentrations and age-related macular degeneration.

Age-related macular degeneration (AMD) is the principal cause of blindness in the elderly population. A strong effect on AMD risk has been reported for genetic variants at the CFH locus, encompassing complement factor H (CFH) and the complement-factor-H-related (CFHR) genes, but the underlying mechanisms are not fully understood. We aimed to dissect the role of factor H (FH) and FH-related (FHR) proteins in AMD in a cohort of 202 controls and 216 individuals with AMD. We detected elevated systemic levels of FHR-1 (p = 1.84 × 10-6), FHR-2 (p = 1.47 × 10-4), FHR-3 (p = 1.05 × 10-5) and FHR-4A (p = 1.22 × 10-2) in AMD, whereas FH concentrations remained unchanged. Common AMD genetic variants and haplotypes at the CFH locus strongly associated with FHR protein concentrations (e.g., FH p.Tyr402His and FHR-2 concentrations, p = 3.68 × 10-17), whereas the association with FH concentrations was limited. Furthermore, in an International AMD Genomics Consortium cohort of 17,596 controls and 15,894 individuals with AMD, we found that low-frequency and rare protein-altering CFHR2 and CFHR5 variants associated with AMD independently of all previously reported genome-wide association study (GWAS) signals (p = 5.03 × 10-3 and p = 2.81 × 10-6, respectively). Low-frequency variants in CFHR2 and CFHR5 led to reduced or absent FHR-2 and FHR-5 concentrations (e.g., p.Cys72Tyr in CFHR2 and FHR-2, p = 2.46 × 10-16). Finally, we showed localization of FHR-2 and FHR-5 in the choriocapillaris and in drusen. Our study identifies FHR proteins as key proteins in the AMD disease mechanism. Consequently, therapies that modulate FHR proteins might be effective for treating or preventing progression of AMD. Such therapies could target specific individuals with AMD on the basis of their genotypes at the CFH locus.

Relationship between rs1410996 polymorphism of CFH gene and essential hypertension patients of Han from Yunnan Province.

OBJECTIVE: To explore the relationship between rs1410996 polymorphism of CFH gene and essential hypertension (EH) in the Yunnan Han population. METHODS: rs1410996 of CFH gene was genotyped based on the collected clinical phenotypes of the EH patients (n = 520) and healthy people (n = 494). RESULTS: On the genotype model and dominance model, there was no relationship between rs1410996 of CFH gene and EH after adjustment (P > 0.05). On the dominance model of male EH patients, the pulse pressure (PP) level of CC genotype carriers was higher than that of (CT + TT) genotype carriers after adjustment (P < 0.05). CONCLUSION: rs1410996 of CFH gene has no correlation with the genetic susceptibility to EH in the Yunnan Han population, but it is related to the PP level in male patients.

Characterization of patients with aHUS and associated triggers or clinical conditions: A Global aHUS Registry analysis.

INTRODUCTION: Atypical haemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy (TMA) associated with complement dysregulation; aHUS may be associated with other 'triggers' or 'clinical conditions'. This study aimed to characterize this patient population using data from the Global aHUS Registry, the largest collection of real-world data on patients with aHUS. METHODS: Patients enrolled in the Global aHUS Registry between April 2012 and June 2021 and with recorded aHUS-associated triggers or clinical conditions prior/up to aHUS onset were analysed. aHUS was diagnosed by the treating physician. Data were classified by age at onset of aHUS (< or ≥18 years) and additionally by the presence/absence of identified pathogenic complement genetic variant(s) and/or anti-complement factor H (CFH) antibodies. Genetically/immunologically untested patients were excluded. RESULTS: 1947 patients were enrolled in the Global aHUS Registry by June 2021, and 349 (17.9%) met inclusion criteria. 307/349 patients (88.0%) had a single associated trigger or clinical condition and were included in the primary analysis. Malignancy was most common (58/307, 18.9%), followed by pregnancy and acute infections (both 53/307, 17.3%). Patients with an associated trigger or clinical condition were generally more likely to be adults at aHUS onset. CONCLUSION: Our analysis suggests that aHUS-associated triggers or clinical conditions may be organized into clinically relevant categories, and their presence does not exclude the concurrent presence of pathogenic complement genetic variants and/or anti-CFH antibodies. Considering a diagnosis of aHUS with associated triggers or clinical conditions in patients presenting with TMA may allow faster and more appropriate treatment.

Anti-C5 monoclonal antibody treatment showing pathological resolution of complement-mediated atypical hemolytic uremic syndrome: a case report.

BACKGROUND: No reports have shown histological changes before and after anti-C5 monoclonal antibody treatment in patients with atypical hemolytic uremic syndrome (aHUS). Here, we report a rare case of complement-mediated aHUS with a complement factor H (CFH) mutation and anti-CFH antibodies who underwent multiple kidney biopsies. CASE PRESENTATION: A 53-year-old woman developed aHUS with CFH gene mutation [c.3572C > T (p. Ser1191 Leu)] and anti-CFH antibodies. Her father had succumbed to acute kidney injury (AKI) in his 30 s. She exhibited AKI, thrombocytopenia, and hemolytic anemia with schistocytes. After improving the platelet count with one session of plasma exchange, a kidney biopsy was performed one month after the onset of symptoms. Blood vessel thrombosis, obvious endothelial swelling, endocapillary hypercellularity, and subendothelial exudative lesions in the glomeruli and arterioles were detected. Anti-C5 monoclonal antibody treatment with eculizumab immediately improved disease activity. A second biopsy 3 months later revealed marked improvement of endothelial injuries with residual membrane double contours and exudative lesions. A third biopsy at 17 months after gradual improvement of kidney function showed a further decrease of double contours along with alterations of the exudative lesions to fibrous intimal thickening. CONCLUSIONS: This is the first report showing the pathophysiology of aHUS in the kidneys and the efficacy of anti-C5 monoclonal antibody treatment by presenting serial kidney pathological features before and after anti-C5 monoclonal antibody treatment. Since her CFH mutation was considered the most important pathological condition, treatment centered on eculizumab was administered, resulting in a good long-term prognosis. In addition, kidney pathological resolution in aHUS occurred over 1 year after anti-C5 monoclonal antibody treatment.

Association of the Complement Factor H Y402H Polymorphism and Response to Anti-Vascular Endothelial Growth Factor Treatment in Age-Related Macular Degeneration: An Updated Meta-Analysis.

INTRODUCTION: Anti-vascular endothelial growth factor (anti-VEGF) agents have a variable effect on patients with age-related macular degeneration (AMD) that has been attributed to several causes, including genetic factors. We evaluated the effects of Complement Factor H (CFH) rs1061170/Y402H polymorphism on the response to anti-VEGF therapy among AMD patients. METHODS: PubMed, Scopus, EMBASE, Web of Science, and Google Scholar were used for a literature search. Pooled odds ratios (ORs) and their 95% confidence intervals (CIs) were estimated to assess the effects of CFH Y402H polymorphism on the response to anti-VEGF therapy in AMD. I2 was used to present the amount of heterogeneity. We used STATA version 14.0 software. RESULTS: Twenty-five papers reporting data for 4,681 patients were included in this study. Better response to anti-VEGF therapy was seen in T over C (OR = 1.25, 95% CI = 1.04-1.50), TT over CC (OR = 1.60, 95% CI = 1.06-2.4), and TT + TC over CC (OR = 1.68, 95% CI = 1.23-2.28) genotypes. There was no significant difference in the three other genetic models (TT vs. TC, TT vs. TC + CC, TC vs. TT + CC). In Asians, no significant difference was observed in all six genetic models. Ranibizumab and bevacizumab had similar efficacy; however, conbercept was more effective in homozygous genotypes. The literature indicated that TT and TC genotypes and T allele were associated with a better functional response, while the CC genotype and C alleles had a better anatomical response. The combination of risk alleles in ARMS2 A69S (rs10490924), VEGF-A (rs699947), and VEGF-A (rs833069) with Y420H is a predictor of non-respondents. CONCLUSION: In patients with AMD, the CFH Y402H is a predictor of the response to anti-VEGF agents and should be considered in the treatment plan.

Association between circulatory complement activation and hypertensive renal damage: a case-control study.

OBJECTIVE: The aim of this study was to investigate the potential importance of complement system activation, with particular emphasis on the complement alternative pathway (AP), in the pathogenesis of hypertensive renal damage. METHODS: Serum complement C3, complement Factor H (CFH) and AP activation were assessed in 66 participants with established essential hypertension with renal damage (RD). Fifty-nine patients with age- and sex-matched essential hypertension without renal damage (NRD) and 58 healthy participants (normal) were selected. RESULTS: Our study revealed that C3 and AP50 continuously increased from normal to NRD to RD (p < 0.05, respectively), while CFH was significantly lower than that in NRD and healthy participants (p < 0.05, respectively). After multifactorial logistic regression analysis corrected for confounders, elevated serum C3 (p = 0.001) and decreased CFH (p < 0.001) were found to be independent risk factors for hypertension in healthy participants; elevated serum C3 (p = 0.034), elevated AP50 (p < 0.001), decreased CFH (p < 0.001), increased age (p = 0.011) and increased BMI (p = 0.013) were found to be independent risk factors for the progression of hypertension to hypertensive renal damage; elevated serum C3 (p = 0.017), elevated AP50 (p = 0.023), decreased CFH (p = 0.005) and increased age (p = 0.041) were found to be independent risk factors for the development of hypertensive renal damage in healthy participants. CONCLUSION: Abnormal activation of complement, particularly complement AP, may be a risk factor for the development and progression of hypertensive renal damage.

Antibody recognition of complement factor H reveals a flexible loop involved in atypical hemolytic uremic syndrome pathogenesis.

Atypical hemolytic uremic syndrome (aHUS) is a disease associated with dysregulation of the immune complement system, especially of the alternative pathway (AP). Complement factor H (CFH), consisting of 20 domains called complement control protein (CCP1-20), downregulates the AP as a cofactor for mediating C3 inactivation by complement factor I. However, anomalies related to CFH are known to cause excessive complement activation and cytotoxicity. In aHUS, mutations and the presence of anti-CFH autoantibodies (AAbs) have been reported as plausible causes of CFH dysfunction, and it is known that CFH-related aHUS carries a high probability of end-stage renal disease. Elucidating the detailed functions of CFH at the molecular level will help to understand aHUS pathogenesis. Herein, we used biophysical data to reveal that a heavy-chain antibody fragment, termed VHH4, recognized CFH with high affinity. Hemolytic assays also indicated that VHH4 disrupted the protective function of CFH on sheep erythrocytes. Furthermore, X-ray crystallography revealed that VHH4 recognized the Leu1181-Leu1189CCP20 loop, a known anti-CFH AAbs epitope. We next analyzed the dynamics of the C-terminal region of CFH and showed that the epitopes recognized by anti-CFH AAbs and VHH4 were the most flexible regions in CCP18-20. Finally, we conducted mutation analyses to elucidate the mechanism of VHH4 recognition of CFH and revealed that VHH4 inserts the Trp1183CCP20 residue of CFH into the pocket formed by the complementary determining region 3 loop. These results suggested that anti-CFH AAbs may adopt a similar molecular mechanism to recognize the flexible loop of Leu1181-Leu1189CCP20, leading to aHUS pathogenesis.

The Noncanonical Role of Complement Factor H in Retinal Pigment Epithelium (RPE) Cells and Implications for Age-Related Macular Degeneration (AMD).

Age-related macular degeneration (AMD) is a complex degenerative disease of the retina. Dysfunction of the retinal pigment epithelium (RPE) occurs in early stages of AMD, and progressive RPE atrophy leads to photoreceptor death and visual impairments that ultimately manifest as geographic atrophy (GA), one of the late-stage forms of AMD. AMD is caused by a combination of risk factors including aging, lifestyle choices, and genetic predisposition. A gene variant in the complement factor H gene (CFH) that leads to the Y402H polymorphism in the factor H protein (FH) confers the second highest risk for the development and progression of AMD. FH is a major negative regulator of the alternative pathway of the complement system, and the FH Y402H variant leads to increased complement activation, which is detectable in AMD patients. For this reason, various therapeutic approaches targeting the complement system have been developed, however, so far with very limited or no efficacy. Interestingly, recent studies suggest roles for FH beyond complement regulation. Here, we will discuss the noncanonical functions of FH in RPE cells and highlight the potential implications of those functions for future therapeutic approaches.

Underlying Genetics of aHUS: Which Connection with Outcome and Treatment Discontinuation?

Atypical hemolytic uremic syndrome (aHUS) is a rare disease caused by a genetic dysregulation of the alternative complement pathway, characterized by thrombocytopenia, hemolytic anemia, and acute kidney injury, and included in the group of thrombotic microangiopathies. With the introduction of humanized monoclonal antibodies that inhibit C5 activation, the natural history of aHUS completely changed, with a better prognosis, a quick recovery of renal function, and a significant reduction of end-stage renal disease incidence. Nowadays, there is an increasing interest in the molecular and genetic bases of this severe disease. The aim of this narrative review is to provide readers with a practical guide about different possible involved genes, elucidating the specific role of each transcribed protein in the pathogenesis of aHUS. Moreover, we analyzed the main current evidence about the relationship among genetic mutations, outcomes, and the risk of recurrence of this manifold disease.

Pathogenic Neisseria Bind the Complement Protein CFHR5 via Outer Membrane Porins.

Neisseria meningitidis and Neisseria gonorrhoeae are important human pathogens that have evolved to bind the major negative regulator of the complement system, complement factor H (CFH). However, little is known about the interaction of pathogens with CFH-related proteins (CFHRs) which are structurally similar to CFH but lack the main complement regulatory domains found in CFH. Insights into the role of CFHRs have been hampered by a lack of specific reagents. We generated a panel of CFHR-specific monoclonal antibodies and demonstrated that CFHR5 was bound by both pathogenic Neisseria spp. We showed that CFHR5 bound to PorB expressed by both pathogens in the presence of sialylated lipopolysaccharide and enhanced complement activation on the surface of N. gonorrhoeae. Our study furthered our understanding of the interactions of CFHRs with bacterial pathogens and revealed that CFHR5 bound the meningococcus and gonococcus via similar mechanisms.

Bioinformatic identification of differentially expressed genes regulated by DNA-methylation in glioblastoma.

DNA methylation-driven differentially expressed genes (DEGs) play potentially important roles in glioblastoma (GBM). In the present study, we applied bioinformatic analyses to identify key methylation-regulated DEGs (MeDEGs) in glioblastoma and elucidate their functions. Gene expression and methylation profile data from glioblastoma samples along with clinical information were obtained from GEO and TCGA databases. A total of 65 genes were identified as MeDEGs from the aforementioned data. Subsequently, gene ontology and kyoto encyclopaedia of genes and genomes enrichment analyses of these MeDEGs exhibited that MeDEGs were mostly enriched in several tumour-related terms such as 'activation of cysteine-type endopeptidase activity involved in apoptotic process' and 'phospholipid scrambling'. Kaplan-Meier survival analysis demonstrated significant correlation of CASP1, CFH and TTLL7 hyper-methylation with patient prognosis. Finally, CASP1 protein could indirectly interact with CFH protein, but interaction of TTLL7 protein with CASP1 or CFH protein was not evident. Based on gene set enrichment analysis, hyper-methylation of CASP1, CFH and TTLL7 were found enriched in tumour-related KEGG terms, such as 'RNA degradation', 'apyruvate metabolism' and 'nitrogen metabolism'. Methylation levels of CASP1, CFH and TTLL7 were addressed to negatively correlate with their mRNA levels in GBM cell lines. In sum, the present identification of MeDEGs associated with overall survival put forth potential molecular targets for translation towards improved diagnosis and treatment of GBM, and specifically, methylation levels of CASP1, CFH and TTLL7 genes could serve as key prognostic biomarkers in GBM.

Protective chromosome 1q32 haplotypes mitigate risk for age-related macular degeneration associated with the CFH-CFHR5 and ARMS2/HTRA1 loci.

BACKGROUND: Single-variant associations with age-related macular degeneration (AMD), one of the most prevalent causes of irreversible vision loss worldwide, have been studied extensively. However, because of a lack of refinement of these associations, there remains considerable ambiguity regarding what constitutes genetic risk and/or protection for this disease, and how genetic combinations affect this risk. In this study, we consider the two most common and strongly AMD-associated loci, the CFH-CFHR5 region on chromosome 1q32 (Chr1 locus) and ARMS2/HTRA1 gene on chromosome 10q26  (Chr10 locus). RESULTS: By refining associations within the CFH-CFHR5 locus, we show that all genetic protection against the development of AMD in this region is described by the combination of the amino acid-altering variant CFH I62V (rs800292) and genetic deletion of CFHR3/1. Haplotypes based on CFH I62V, a CFHR3/1 deletion tagging SNP and the risk variant CFH Y402H are associated with either risk, protection or neutrality for AMD and capture more than 99% of control- and case-associated chromosomes. We find that genetic combinations of CFH-CFHR5 haplotypes (diplotypes) strongly influence AMD susceptibility and that individuals with risk/protective diplotypes are substantially protected against the development of disease. Finally, we demonstrate that AMD risk in the ARMS2/HTRA1 locus is also mitigated by combinations of CFH-CFHR5 haplotypes, with Chr10 risk variants essentially neutralized by protective CFH-CFHR5 haplotypes. CONCLUSIONS: Our study highlights the importance of considering protective CFH-CFHR5 haplotypes when assessing genetic susceptibility for AMD. It establishes a framework that describes the full spectrum of AMD susceptibility using an optimal set of single-nucleotide polymorphisms with known functional consequences. It also indicates that protective or preventive complement-directed therapies targeting AMD driven by CFH-CFHR5 risk haplotypes may also be effective when AMD is driven by ARMS2/HTRA1 risk variants.

A CFH peptide-decorated liposomal oxymatrine inactivates cancer-associated fibroblasts of hepatocellular carcinoma through epithelial-mesenchymal transition reversion.

Cancer-associated fibroblasts (CAFs) deteriorate tumor microenvironment (TME) and hinder intra-tumoral drug delivery. Direct depleting CAFs exists unpredictable risks of tumor metastasis. Epithelial-mesenchymal transition (EMT) is a critical process of CAFs converted from hepatic stellate cells during hepatocellular tumorigenesis; however, until now the feasibility of reversing EMT to battle hepatocellular carcinoma has not been comprehensively explored. In this study, we report a CFH peptide (CFHKHKSPALSPVGGG)-decorated liposomal oxymatrine (CFH/OM-L) with a high affinity to Tenascin-C for targeted inactivating CAFs through reversing EMT, which is verified by the upregulation of E-cadherin and downregulation of vimentin, N-cadherin, and snail protein in vivo and in vitro. After the combination with icaritin-loaded lipid complex, CFH/OM-L obviously boosts the comprehensive anticancer efficacy in both 3D tumor spheroids and stromal-rich tumor xenograft nude mouse models. The combinational therapy not only effectively reversed the in vivo EMT process but also significantly lowered the collagen, creating favorable conditions for deep penetration of nanoparticles. More importantly, CFH/OM-L does not kill but inactivates CAFs, resulting in not only a low risk of tumor metastasis but also a reprogramming TME, such as M1 tumor-associated macrophages polarization and natural killer cells activation. Such strategy paves a moderate way to remold TME without depleting CAFs and provides a powerful tool to design strategies of combinational hepatocellular carcinoma therapy.

Humanized C3 Mouse: A Novel Accelerated Model of C3 Glomerulopathy.

BACKGROUND: C3 glomerulopathy (C3G) is characterized by the alternative-pathway (AP) hyperactivation induced by nephritic factors or complement gene mutations. Mice deficient in complement factor H (CFH) are a classic C3G model, with kidney disease that requires several months to progress to renal failure. Novel C3G models can further contribute to understanding the mechanism behind this disease and developing therapeutic approaches. METHODS: A novel, rapidly progressing, severe, murine model of C3G was developed by replacing the mouse C3 gene with the human C3 homolog using VelociGene technology. Functional, histologic, molecular, and pharmacologic assays characterize the presentation of renal disease and enable useful pharmacologic interventions in the humanized C3 (C3hu/hu) mice. RESULTS: The C3hu/hu mice exhibit increased morbidity early in life and die by about 5-6 months of age. The C3hu/hu mice display elevated biomarkers of kidney dysfunction, glomerulosclerosis, C3/C5b-9 deposition, and reduced circulating C3 compared with wild-type mice. Administration of a C5-blocking mAb improved survival rate and offered functional and histopathologic benefits. Blockade of AP activation by anti-C3b or CFB mAbs also extended survival and preserved kidney function. CONCLUSIONS: The C3hu/hu mice are a useful model for C3G because they share many pathologic features consistent with the human disease. The C3G phenotype in C3hu/hu mice may originate from a dysregulated interaction of human C3 protein with multiple mouse complement proteins, leading to unregulated C3 activation via AP. The accelerated disease course in C3hu/hu mice may further enable preclinical studies to assess and validate new therapeutics for C3G.

Clinical features of children with anti-CFH autoantibody-associated hemolytic uremic syndrome: a report of 8 cases.

OBJECTIVE: To explore the clinical characteristics, treatment protocol and prognosis of children with anti-complement factor H (CFH) autoantibody (Ab)-associated hemolytic uremic syndrome (HUS). METHODS: Clinical data of 8 patients with anti-CFH Ab-associated HUS who were admitted to Shandong Provincial Hospital from January 2011 to December 2020 were collected retrospectively. RESULTS: The age at disease onset ranged between 5.83 and 13.5 years, with a male: female ratio of 1.67:1. The time of onset was distributed from May to June and November to December. Digestive and upper respiratory tract infections were common prodromal infections. Positivity for anti-CFH Ab and reduced C3 levels were observed among all patients. Heterozygous mutation of the CHFR5 gene (c.669del A) and homozygous loss of the CFHR1 gene [loss2(EXON:2-6)] were found in two patients. All patients received early treatment with plasma exchange and corticosteroid therapy. Six patients were given immunosuppressive agents (cyclophosphamide and/or mycophenolate mofetil) for persistent proteinuria. The follow-up period was 12-114 months. Four of 8 patients achieved complete remission, 3 achieved partial remission, and 1 died. Relapse occurred in two patients. CONCLUSION: Children with anti-CFH Ab-associated HUS were mainly school-aged and predominantly male, with onset times of summer and winter. Digestive and upper respiratory tract infections were common prodromal infections. Plasma exchange combined with methylprednisolone pulse therapy in the acute phase and cyclophosphamide or mycophenolate mofetil treatment for maintenance can be utilized in children with anti-CFH Ab-associated HUS if eculizumab is not available.

Early relapse rate determines further relapse risk: results of a 5-year follow-up study on pediatric CFH-Ab HUS.

BACKGROUND: The complement factor H antibody (CFH-Ab)-associated hemolytic uremic syndrome (HUS) forms a distinct subgroup within the complement-mediated HUS disease spectrum. The autoimmune nature of this HUS subgroup implies the potential benefit of a targeted immunosuppressive therapy. Data on long-term outcome are scarce. METHODS: This observational study evaluates the clinical outcome of 19 pediatric CFH-Ab HUS patients from disease onset until their 5-year follow-up. RESULTS: All but one relapse occurred during the first 2 years, and patients who had no relapse within the first 6 months were relapse-free until the end of the observation period. Kidney function at disease onset determines long-term kidney function: all individuals with normal kidney function at disease onset had normal kidney function after 5 years, and all patients with reduced kidney function at onset had impaired kidney function at the last follow-up. Level of CFH-Ab titer at disease onset was not correlated with a higher risk of recurrences or worse long-term outcome after 5 years. Resolution of CFH-Ab titers after 5 years was common. CONCLUSIONS: CFH-Ab HUS patients have a varied overall long-term course. Early relapses are common, making close surveillance during the first years essential, regardless of the initial CFH-Ab titer.

Recurrent structural variation, clustered sites of selection, and disease risk for the complement factor H (CFH) gene family.

Structural variation and single-nucleotide variation of the complement factor H (CFH) gene family underlie several complex genetic diseases, including age-related macular degeneration (AMD) and atypical hemolytic uremic syndrome (AHUS). To understand its diversity and evolution, we performed high-quality sequencing of this ∼360-kbp locus in six primate lineages, including multiple human haplotypes. Comparative sequence analyses reveal two distinct periods of gene duplication leading to the emergence of four CFH-related (CFHR) gene paralogs (CFHR2 and CFHR4 ∼25-35 Mya and CFHR1 and CFHR3 ∼7-13 Mya). Remarkably, all evolutionary breakpoints share a common ∼4.8-kbp segment corresponding to an ancestral CFHR gene promoter that has expanded independently throughout primate evolution. This segment is recurrently reused and juxtaposed with a donor duplication containing exons 8 and 9 from ancestral CFH, creating four CFHR fusion genes that include lineage-specific members of the gene family. Combined analysis of >5,000 AMD cases and controls identifies a significant burden of a rare missense mutation that clusters at the N terminus of CFH [P = 5.81 × 10-8, odds ratio (OR) = 9.8 (3.67-Infinity)]. A bipolar clustering pattern of rare nonsynonymous mutations in patients with AMD (P < 10-3) and AHUS (P = 0.0079) maps to functional domains that show evidence of positive selection during primate evolution. Our structural variation analysis in >2,400 individuals reveals five recurrent rearrangement breakpoints that show variable frequency among AMD cases and controls. These data suggest a dynamic and recurrent pattern of mutation critical to the emergence of new CFHR genes but also in the predisposition to complex human genetic disease phenotypes.

CFH and VIPR2 as susceptibility loci in choroidal thickness and pachychoroid disease central serous chorioretinopathy.

Central serous chorioretinopathy (CSC) is a common disease affecting younger people and may lead to vision loss. CSC shares phenotypic overlap with age-related macular degeneration (AMD). As recent studies have revealed a characteristic increase of choroidal thickness in CSC, we conducted a genome-wide association study on choroidal thickness in 3,418 individuals followed by TaqMan assays in 2,692 subjects, and we identified two susceptibility loci: CFH rs800292, an established AMD susceptibility polymorphism, and VIPR2 rs3793217 (P = 2.05 × 10-10 and 6.75 × 10-8, respectively). Case-control studies using patients with CSC confirmed associations between both polymorphisms and CSC (P = 5.27 × 10-5 and 5.14 × 10-5, respectively). The CFH rs800292 G allele is reportedly a risk allele for AMD, whereas the A allele conferred risk for thicker choroid and CSC development. This study not only shows that susceptibility genes for CSC could be discovered using choroidal thickness as a defining variable but also, deepens the understanding of differences between CSC and AMD pathophysiology.

Drusenoid Pigment Epithelial Detachment: Genetic and Clinical Characteristics.

Few studies report drusenoid pigment epithelial detachment (DPED) in Asians. In this multicenter study, we report the clinical and genetic characteristics of 76 patients with DPED, and, for comparison, 861 patients with exudative age-related macular degeneration (AMD) were included. On the initial presentation, the mean best-corrected visual acuity was 0.087 ± 0.17 (logMAR unit), and mean DPED height and width were 210 ± 132 and 1633 ± 1114 µm, respectively. Fifty-one (67%) patients showed macular neovascularization in the contralateral eye. The risk allele frequency of both ARMS2 A69S and CFH I62V was significantly higher in DPED than in typical AMD and polypoidal choroidal vasculopathy (PCV) (ARMS2 A69S risk allele frequency: DPED 77% vs. typical AMD 66% vs. PCV 57%, CFH I62V risk allele frequency: DPED 87% vs. typical AMD 73% vs. PCV 73%), although the risk allele frequency of both genes was similar between the DPED group and retinal angiomatous proliferation (RAP) group (ARMS2 A69S: p = 0.32, CFH I62V, p = 0.11). The prevalence of reticular pseudodrusen (RPD) was highest in RAP (60%), followed by DPED (22%), typical AMD (20%), and PCV (2%). Although the prevalence of RPD differs between DPED and RAP, these entities share a similar genetic background in terms of ARMS2 and CFH genes.