The hypothetical molecular mechanism of the ethnic variations in the manifestation of age-related macular degeneration; focuses on the functions of the most significant susceptibility genes

Age-related macular degeneration (AMD) is the leading sight-threatening disease in developed countries. On the other hand, recent studies indicated an ethnic variation in the phenotype of AMD. For example, several reports demonstrated that the incidence of drusen in AMD patients is less in Asians compared to Caucasians though the reason has not been clarified yet. In the last decades, several genome association studies have disclosed many susceptible genes of AMD and revealed that the association strength of some genes was different among races and AMD phenotypes. In this review article, the essential findings of the clinical studies and genome association studies for the most significant genes CFH and ARMS2/HTRA1 in AMD of different races are summarized, and theoretical hypotheses about the molecular mechanisms underlying the ethnic variation in the AMD manifestation mainly focused on those genes between Caucasians and Asians are discussed.

Association of Genetic Variants with Polypoidal Choroidal Vasculopathy: A Systematic Review and Updated Meta-analysis

TOPIC

A systematic review and meta-analysis of the genetic association with polypoidal choroidal vasculopathy (PCV) and the genetic difference between PCV and neovascular age-related macular degeneration (nAMD).

CLINICAL RELEVANCE

To identify genetic biomarkers that are potentially useful for genetic diagnosis of PCV and for differentiating PCV from nAMD.

METHODS

We performed a literature search in EMBASE, PubMed, Web of Science, and the Chinese Biomedical Database for PCV genetic studies published before February 6, 2015. We then conducted a meta-analysis of all polymorphisms that had sufficient genotype/allele data reported in ≥2 studies and estimated the summary odds ratio (OR) and 95% confidence intervals (CIs) for PCV. We also compared the association profiles between PCV and nAMD, and performed a sensitivity analysis.

RESULTS

A total of 66 studies were included in the meta-analysis, involving 56 polymorphisms in 19 genes/loci. In total, 31 polymorphisms in 10 genes/loci (age-related maculopathy susceptibility 2 [ARMS2], high-temperature requirement factor A1 [HTRA1], complement factor H [CFH], complement component 2 [C2], CFB, RDBP, SKIV2L, CETP, 8p21, and 4q12) were significantly associated with PCV. Another 25 polymorphisms in 13 genes (ARMS2, HTRA1, C2, CFB, ELN, LIPC, LPL, ABCA1, VEGF-A, TLR3, LOXL1, SERPING1, and PEDF) had no significant association. Twelve polymorphisms at the ARMS2-HTRA1 locus showed significant differences between PCV and nAMD. The sensitivity analysis validated the significance of our analysis.

CONCLUSIONS

This study revealed 31 polymorphisms in 10 genes/loci that contribute to PCV susceptibility. Among them, ARMS2-HTRA1 also showed allelic diversity between PCV and nAMD. Our results confirm the gene variants that could affect the phenotypic expressions of PCV and nAMD.

Spectral-domain optical coherence tomography findings in polypoidal choroidal vasculopathy suggest a type 1 neovascular growth pattern

PURPOSE

To report spectral-domain optical coherence tomography (SD-OCT) findings in polypoidal choroidal vasculopathy (PCV).

PATIENTS AND METHODS

Seventeen eyes of 15 consecutive patients diagnosed with PCV based on typical clinical and angiographic findings were imaged with macular SD-OCT including line scans passing through the polyps.

RESULTS

SD-OCT findings included typical and atypical retinal pigment epithelial (RPE) detachments and subretinal and intraretinal fluid in all eyes. In the areas corresponding to the polypoidal lesions, well-delineated round-oval, sub-RPE cavities were present and were adherent to the posterior surface of the detached RPE above Bruch membrane. No retinal or choroidal connections to the cavities were noted.

CONCLUSION

These SD-OCT findings document that the vascular lesions in PCV are not located in the inner choroid, but in the sub-RPE space, suggesting that PCV is a variant of type 1 choroidal neovascularization rather than a distinct clinical entity as initially thought.

Polypoidal choroidal vasculopathy: clinical features and genetic predisposition

Polypoidal choroidal vasculopathy (PCV) is currently recognized as a phenotype of age-related macular degeneration (AMD). PCV is believed to be a type of choroidal neovascularization, although some cases of PCV show a distinct vascular abnormality of the choroidal vessels. PCV often shows several unique clinical manifestations which are apparently different from typical neovascular AMD (tAMD). In addition, the natural course and response to treatment are often different between tAMD and PCV. Moreover, recent genetic studies suggested a possible difference in the genetic susceptibility to disease between tAMD and PCV, as well as the existence of heterogeneity among PCV cases. In viewing the accumulation of knowledge about PCV, we have summarized the recent literature regarding PCV in this review article to improve the understanding of this clinical entity including possible susceptibility genes. We will also discuss the optimal treatment strategies for PCV in accordance with the results of recent clinical and genetic studies.