RESUMEN
Age-related macular degeneration (AMD) is a complex neurodegenerative eye disease with behavioral and genetic etiology and is the leading cause of irreversible vision loss among elderly Caucasians. Functionally significant genetic variants in the alternative pathway of complement have been strongly linked to disease. More recently, a rare variant in the terminal pathway of complement has been associated with increased risk, Complement component 9 (C9) P167S. To assess the functional consequence of this variant, C9 levels were measured in two independent cohorts of AMD patients. In both cohorts, it was demonstrated that the P167S variant was associated with low C9 plasma levels. Further analysis showed that patients with advanced AMD had elevated sC5b-9 compared to those with non-advanced AMD, although this was not associated with the P167S polymorphism. Electron microscopy of membrane attack complexes (MACs) generated using recombinantly produced wild type or P167S C9 demonstrated identical MAC ring structures. In functional assays, the P167S variant displayed a higher propensity to polymerize and a small increase in its ability to induce hemolysis of sheep erythrocytes when added to C9-depleted serum. The demonstration that this C9 P167S AMD risk polymorphism displays increased polymerization and functional activity provides a rationale for the gene therapy trials of sCD59 to inhibit the terminal pathway of complement in AMD that are underway.
Asunto(s)
Complemento C9/genética , Predisposición Genética a la Enfermedad/genética , Degeneración Macular/genética , Mutación , Anciano , Animales , Células CHO , Estudios de Casos y Controles , Estudios de Cohortes , Complemento C9/metabolismo , Complejo de Ataque a Membrana del Sistema Complemento/metabolismo , Proteínas del Sistema Complemento/genética , Proteínas del Sistema Complemento/metabolismo , Cricetinae , Cricetulus , Femenino , Cobayas , Hemólisis , Humanos , Degeneración Macular/sangre , Degeneración Macular/metabolismo , Masculino , Polimerizacion , Factores de Riesgo , OvinosRESUMEN
This study assessed variation in plasma levels of the complement regulatorC1 inhibitor (C1inh) in patients with age related macular degeneration (AMD) and controls. Plasma from391 AMD cases and 370 controls was assayed by rate nephelometry to determine C1inh protein levels. Protein levels were analysed for relationships with age, gender, smoking, AMD disease status and genetic variation in the SERPING1 gene, which encodes C1inh, using a multivariate analysis. t-Tests show a significant difference in C1inh levels in AMD cases compared with controls (p=2.340E-6), smokers compared to non-smokers (p=1.022E-4) and females compared to males (p=1.661E-7). Multivariate analysis shows that after accounting for gender and smoking AMD status remained significant. Age was included in the model but was not significant. Including genetic variation in the model shows that one significant SNP (rs2649663) 5' of the SERPING1 gene is associated with C1inh levels though this SNP is not associated with AMD. This suggests that genetic variation in the promoter region of the SERPING1 gene may influence expression of the gene.
Asunto(s)
Proteínas Inactivadoras del Complemento 1/genética , Proteína Inhibidora del Complemento C1/análisis , Proteína Inhibidora del Complemento C1/inmunología , Degeneración Macular/genética , Anciano , Anciano de 80 o más Años , Complemento C1/antagonistas & inhibidores , Femenino , Predisposición Genética a la Enfermedad , Variación Genética , Genotipo , Humanos , Degeneración Macular/sangre , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Regiones Promotoras Genéticas/genética , Factores Sexuales , FumarRESUMEN
PURPOSE: To identify the prevalence of myocilin gene mutations in a UK glaucoma cohort. METHODS: Primary open-angle (POAG) and normal tension glaucoma patients were recruited from the Southampton University Hospital Trust Eye Clinic and satellite regional glaucoma clinics. Phenotype data relating to disease history and other potential risk factors were recorded and blood samples collected for each consenting participant. Point mutation analysis of the myocilin gene was carried out using six overlapping PCR fragments covering the entire coding sequence of the gene. A total of 316 POAG samples were examined of which 7 (2.2 %) tested positive for disease-causing mutations in this gene. One of these seven non-synonymous mutations represented a previously unreported amino-acid substitution of cysteine for arginine at codon 296 (p.R296C) of the myocilin protein. CONCLUSIONS: This study identifies a 2.2% prevalence of myocilin mutations in a cohort of ethnically homogenous glaucoma patients selected from a UK ophthalmic clinic. A novel myocilin mutation is also described. This study identifies that myocilin genetic screening is feasible in NHS glaucoma clinics for genetic counselling and cascade testing of relatives of patients affected by myocilin glaucoma.
Asunto(s)
Proteínas del Citoesqueleto/genética , Proteínas del Ojo/genética , Glaucoma/genética , Glicoproteínas/genética , Mutación Puntual/genética , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , Análisis Mutacional de ADN , Exones/genética , Estudios de Factibilidad , Femenino , Glaucoma/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Análisis de Secuencia de ADN , Reino Unido/epidemiologíaRESUMEN
BACKGROUND/AIMS: To determine whether four expression-related cytokine polymorphisms are associated with age-related macular degeneration (AMD). METHODS: DNA from 478 cases with AMD and 555 normal controls was genotyped for the pro-inflammatory IL1beta -511C/T, IL6 -174C/G, IL8 -251A/T and anti-inflammatory IL10 -1082G/A cytokine polymorphisms using the 5' nuclease TaqMan(R) assay for allelic discrimination. Associations with AMD were analysed using allelic frequencies. RESULTS: The -251A allele of the IL8 promoter gene polymorphism was more prevalent in AMD patients than controls (p = 0.037, OR = 1.21, 95% CI = 1.01 to 1.44). Adjusting for age, sex, body mass index (BMI), current smoking and past smoking status did not alter the AMD association significantly (corrected p value = 0.043, OR = 1.23, 95% CI = 1.0 to 1.50). CONCLUSION: The pro-inflammatory homozygous IL8 -251AA genotype is an important risk factor for AMD. This may have implications for future therapy with biological agents that could target this cytokine.