Dominant radial drusen and Arg345Trp EFEMP1 mutation

Diagnostic definition of malattia leventinese in a family from Colombia

The malattia leventinese is an autosomal dominant inherited disease whose symptoms appear between the second and fourth decades of life. It is characterized by the appearance of drusen located between the retinal pigment epithelium and the Bruch membrane. It is usually associated with low vision and may progress to blindness. The pathogenic variant p.Arg345Trp in the EFEMP1 gene has been associated with this disease. We characterized clinically and molecularly a family with malattia leventinese using a comprehensive approach that involved ophthalmologists, pediatricians, and geneticists. This approach is of great importance since the phenotype of this disease is often confused with acular degeneration. All family members underwent ophthalmological evaluation and DNA extraction from a peripheral blood sample. All exons of the EFEMP1 gene were amplified and sequenced. The pathogenic variant p.Arg345Trp was identified in affected individuals in this family. This is the first report of malattia leventinese in a family with the p.Arg345Trp pathogenic variant in Colombia. The molecular diagnosis of retinal dystrophies is essential to differentiate this type of pathology.

First reported case of Doyne honeycomb retinal dystrophy (Malattia Leventinese/autosomal dominant drusen) in Scandinavia

BACKGROUND

Doyne honeycomb retinal dystrophy (DHRD)/malattia leventinese (ML) is an autosomal dominant, progressive retinal disorder characterized by massive central retinal drusen often partly coalescent forming a characteristic honeycomb-like pattern. Debut of vision loss often occurs in early to mid-adulthood, and the degree varies. A single variant in EFEMP1: c.1033C>T (R345W) has been identified as the cause in all cases.

METHODS

Following DNA isolation, exome sequencing was performed in seven genes associated with flecked retina. Direct sequencing was used for variant verification.

RESULTS

We report the first Scandinavian case of molecular genetically verified DHRD/ML: a 57-year-old woman debuting with vision loss and metamorphopsia. On both eyes, ophthalmological findings included massive hard drusen in the macular region and nasal to the optic disc as well as macular hyperpigmentation. Secondary choroidal neovascularizations were identified on both eyes, and anti-vascular endothelial growth factor was administered, without effect.

CONCLUSION

Molecular genetic investigation revealed heterozygosity for the known pathogenic missense variant in EFEMP1: c.1033C>T (R345W) previously reported in relation to DHRD/ML. Family history revealed no other cases of similar visual impairment suggesting a de novo mutation. Furthermore, there was no correlation between the unique DHRD/ML haplotypes reported in the literature and our patient.

Exome Sequencing Identifies a Missense Variant in EFEMP1 Co-Segregating in a Family with Autosomal Dominant Primary Open-Angle Glaucoma

Primary open-angle glaucoma (POAG) is a clinically important and genetically heterogeneous cause of progressive vision loss as a result of retinal ganglion cell death. Here we have utilized trio-based, whole-exome sequencing to identify the genetic defect underlying an autosomal dominant form of adult-onset POAG segregating in an African-American family. Exome sequencing identified a novel missense variant (c.418C>T, p.Arg140Trp) in exon-5 of the gene coding for epidermal growth factor (EGF) containing fibulin-like extracellular matrix protein 1 (EFEMP1) that co-segregated with disease in the family. Linkage and haplotype analyses with microsatellite markers indicated that the disease interval overlapped a known POAG locus (GLC1H) on chromosome 2p. The p.Arg140Trp substitution was predicted in silico to have damaging effects on protein function and transient expression studies in cultured cells revealed that the Trp140-mutant protein exhibited increased intracellular accumulation compared with wild-type EFEMP1. In situ hybridization of the mouse eye with oligonucleotide probes detected the highest levels of EFEMP1 transcripts in the ciliary body, cornea, inner nuclear layer of the retina, and the optic nerve head. The recent finding that a common variant near EFEMP1 was associated with optic nerve-head morphology supports the possibility that the EFEMP1 variant identified in this POAG family may be pathogenic.

A novel haplotype with the R345W mutation in the EFEMP1 gene associated with autosomal dominant drusen in a Japanese family

PURPOSE

To describe ophthalmic and molecular genetic findings in a family of Japanese patients with Malattia leventinese (ML)/Doyne honeycomb retinal dystrophy (DHRD), also known as autosomal dominant drusen.

METHODS

Four patients with ML/DHRD, including a 42-year-old female proband, were ascertained. The proband underwent complete ophthalmic examinations, including fundus and electrodiagnostic investigations, and Humphrey visual field (VF) perimetry. Mutation screening of the EFEMP1 gene and haplotype analysis were performed in the family, an Indian ML/DHRD family, and a branch of 1 of 39 ML/DHRD families in the United States, in which all affected patients shared a common haplotype.

RESULTS

A heterozygous missense mutation (p.R345W) was identified in all four Japanese patients and in affected patients of the other two families. This mutation was the only mutation that has been exclusively found in the gene. The disease haplotype in the Japanese family was different from those of the other two families. Clinically, central retinas were prominently affected in the proband and her mother, and subsequently the proband developed subfoveal choroidal neovascularization in the left eye, whereas her younger sister with the mutation, who was asymptomatic, exhibited only fine macular drusen. Long-term follow-up of Humphrey VF and multifocal-electroretinography (mfERG) in the proband also revealed progressive attenuation of macular function in the right eye.

CONCLUSIONS

This is the first report to describe a Japanese family with variable expressivity of ML/DHRD, in which a novel disease haplotype was identified. Humphrey VF and mfERG testing may be helpful in determining the long-term outcome of macular function.

Association of EFEMP1 with malattia leventinese and age-related macular degeneration: a mini-review

Malattia leventinese (ML) or Doyne honeycomb retinal dystrophy (DHRD) was the first clinically and histopathologically described Mendelian maculopathy. The gene responsible for ML/DHRD, EFEMPI (fibulin-3/SI-5/FBNL) encodes a member of the fibulin family, a newly recognized family of extracellular matrix proteins. EFEMPImutations have not been found in age-related macular degeneration (AMD) patients despite the close phenotypic similarities between ML/DHRD and AMD. This non-correlating genotype/phenotype relationship between inherited and age-related conditions is typical for common age-related diseases. Biochemical pathways delineated in other diseases indicate that the gene associated with the inherited condition is nonetheless critical in age-related forms. This review summarizes current knowledge relating to ML/DHRD and EFEMPI,with discussion of why EFEMPI mutations are absent in AMD and how EFEMPI may be involved in the pathogenesis of ML/DHRD and AMD.

Fibulins 3 and 5 antagonize tumor angiogenesis in vivo

Lethal tumor growth and progression cannot occur without angiogenesis, which facilitates cancer cell proliferation, survival, and dissemination. Fibulins (FBLN) 5 and 3 are widely expressed extracellular matrix proteins that regulate cell proliferation in a context-specific manner. Reduced FBLN-5 expression has been associated with cancer formation and progression in humans, whereas its constitutive expression antagonizes endothelial cell angiogenic sprouting in vitro. Thus, FBLN-5 may suppress tumorigenesis by preventing tumor angiogenesis. FBLN-3 is homologous to FBLN-5 and expressed in endothelial cells, yet its role in tumorigenesis and angiogenesis is unknown. We find FBLN-3 expression to be altered in some human tumors and that its constitutive expression in endothelial cells inhibited their proliferation, invasion, and angiogenic sprouting, as well as their response to vascular endothelial growth factor as measured by p38 mitogen-activated protein kinase activation. In endothelial cells, both FBLNs (a) reduced angiogenic sprouting stimulated by basic fibroblast growth factor (bFGF); (b) inhibited matrix metalloproteinase expression and activity; and (c) stimulated tissue inhibitor of metalloproteinase expression. More importantly, both FBLNs prevented angiogenesis and vessel infiltration into bFGF-supplemented Matrigel plugs implanted in genetically normal mice, as well as decreased the growth and blood vessel density in tumors produced by MCA102 fibrosarcoma cells implanted s.c. into syngeneic mice. Our findings establish FBLN-3 and FBLN-5 as novel angiostatic agents capable of reducing tumor angiogenesis and, consequently, tumor growth in vivo and suggest that these angiostatic activities may one day be exploited to combat tumor angiogenesis and metastasis in cancer patients.

Indocyanine green angiography features of Malattia leventinese

BACKGROUND/AIM

Malattia leventinese (ML) is an inherited macular degeneration characterised by the presence of small radial drusen. Despite extensive descriptions of this study of the fundus, angiographic features of ML have been inadequately described. The aim is to describe the indocyanine green angiography (ICG) features observed in ML.

METHODS

10 eyes from five consecutive ML patients (aged 27-44 years) were prospectively included. A complete ophthalmological examination including colour fundus photographs, autofluorescence, fluorescein angiography (FA), and ICG was performed.

RESULTS

ICG differentiated two types of drusen. Large round aggregated drusen were consistently hypofluorescent in the early phases and presented as hyperfluorescent spots surrounded by halos of hypofluorescence in the late phases. Conversely, small radial drusen were mostly hyperfluorescent in the early phases with decreased fluorescence in the late phases of the ICG sequence. FA also showed differences in staining between the two types of drusen.

CONCLUSIONS

ICG angiography revealed marked differences between the large round and small radial drusen observed in ML. The large central drusen presented with an unusual pustuliform feature on the late phases of the ICG sequence. This distinct feature may be useful in the diagnosis of late stage disease when drusen consolidation could obscure the radial drusen.

Genetic aspects of age-related macular degeneration

Age-related macular degeneration (AMD) is a complex phenotype that has multiple causes, including genetic. This paper reviews pertinent single-gene disorders, polymorphisms in the human genome that modify disease severity, and maculopathies that provide insight into the pathogenesis of AMD and the function of the normal macula. The availability of DNA-based analysis for certain genes will likely increase the demand for genetic counselling of patients and families with AMD. Better knowledge of risks should help prevent blindness in these families.

Genetic heterogeneity in Malattia Leventinese

Malattia Leventinese (ML) is a dominant macular dystrophy characterized by drusen at the posterior pole. ML has been associated with a single mutation (R345W) in the EGF-containing fibulin-like extracellular matrix protein 1 (EFEMP-1) gene, but also the EFEMP-2 gene, known to share genetic homology with EFEMP-1, is considered a candidate gene for this genetic disorder. We have characterized clinically and genetically seven members of a three-generation family affected by ML. Results showed that five family members were clinically affected but the DNA sequencing failed to reveal the typical R345W mutation. Furthermore, the linkage analysis to EFEMP-1 (using polymorphic markers D2S337 and D2S2368) and to EFEMP-2 (using D11S987 and D11S1314 markers) gave negative results. Therefore, our results suggest EFEMP-1 or EFEMP-2 genes cannot be excluded as being responsible for ML but other genes have to be considered in the pathogenesis of the disease.