Chromosomal sharing in atypical cases of gelatinous drop-like corneal dystrophy.

PURPOSE: To present the phenotypic variability both among and within families in Japanese gelatinous drop-like corneal dystrophy (GDLD), and to study the genetic background of the variability. METHODS: Four Japanese families who suffer from bilateral corneal amyloidoses were studied by a molecular genetic method. All families included a patient whose clinical features alone could not be used to diagnose GDLD. In one family, obvious clinical differences were observed between the two members who were patients. Three families had members who suffered from atypical amyloidoses that had not been initially diagnosed as GDLD. For their final diagnoses and for the investigation of the genetic background of these phenotypes, the sequences of the entire TACSTD2 gene and the genotypes of some polymorphic markers close to the TACSTD2 gene were studied. RESULTS: Genetic analysis revealed that all the patients possessed a homozygous Q118X mutation in TACSTD2, a major founder mutation in Japanese GDLD. There were no differences in the entire sequence of TACSTD2 in these patients compared with other GDLD patients. Moreover, the genotyping of polymorphic markers near the TACSTD2 gene revealed that these patients shared the same founder chromosome as well as the TACSTD2 gene. CONCLUSION: In Japanese GDLD patients, phenotypic variability is observed both among and within families in spite of the allelic homogeneity of Q118X. Even in these atypical cases, the patients shared the same chromosomal region, received from a founder.

Thrombospondin-1 modulates VEGF-A-mediated Akt signaling and capillary survival in the developing retina.

Microvascular development is often perceived to result from a balance of positive and negative factors that impact signaling for proliferation and survival. The survival signaling that results from hypoxia-induced VEGF-A has been well established, but the factors that antagonize this signaling have been poorly studied. As endogenous inhibitors of angiogenesis, thrombospondins (TSPs) are likely candidates to affect survival signaling. Here we report that TSP1 antagonized microvascular survival to retinal hyperoxia, and Akt signaling in both the retina and in cultured endothelial cells. TSP1 expression is correlated with the association of the CD36 receptor with Src versus Fyn. In the presence of TSP1, CD36 is coprecipitated with Fyn as previously shown by others. However, in the absence of TSP1, there is a preferential association with Src. We now demonstrate that these Src family kinases play an important role in modulating microvascular survival in response to TSP1 by crossing tsp1(-/-) mice to the src(-/-) and fyn(-/-) mice and testing the survival of retinal blood vessels in hyperoxia. We find that tsp1(-/-), fyn(-/-), and double-mutant tsp1(-/-)/fyn(-/-) mice have a similar enhancement of capillary survival in oxygen, whereas in a tsp(-/-) background, the loss of only one allele of src restores the balance in survival and apoptosis to that of wild-type mice. Taken together, we hypothesize that TSP1 antagonizes VEGF-driven Akt survival signaling in part through the recruitment of Fyn to membrane domains containing CD36, but when TSP1 is absent, an opposing Src recruitment contributes to VEGF-driven Akt phosphorylation and capillary survival.

Obligatory participation of macrophages in an angiopoietin 2-mediated cell death switch.

Macrophages have a critical function in the recognition and engulfment of dead cells. In some settings, macrophages also actively signal programmed cell death. Here we show that during developmentally scheduled vascular regression, resident macrophages are an obligatory participant in a signaling switch that favors death over survival. This switch occurs when the signaling ligand angiopoietin 2 has the dual effect of suppressing survival signaling in vascular endothelial cells (VECs) and stimulating Wnt ligand production by macrophages. In response to the Wnt ligand, VECs enter the cell cycle and in the absence of survival signals, die from G1 phase of the cell cycle. We propose that this mechanism represents an adaptation to ensure that the macrophage and its disposal capability are on hand when cell death occurs.

Allelic homogeneity in Avellino corneal dystrophy due to a founder effect.

Avellino corneal dystrophy (ACD) is a common corneal dystrophy that shows allelic homogeneity, R124H mutation in the transforming growth factor beta-induced (TGFBI) gene. There are distinct phenotypes of homozygous Avellino corneal dystrophy, termed types I and II. To investigate if the difference is caused by a modifier mutation, we sequenced the entire coding region of TGFBI of two types of ACDs. The sequences obtained from each type were identical, and we could not find any nucleotide alternations. Instead, we found seven single nucleotide polymorphisms (SNPs) compared with the normal control. Primer extension analysis revealed that all 14 homozygous patients were homozygotes in each SNP, which meant that all the patients shared the same disease haplotype. Subsequent analysis of 45 heterozygous ACD patients showed strong linkage disequilibrium between disease alleles of each SNP and ACD. These results strongly suggest that the allelic homogeneity of TGFBI associated corneal dystrophies (ACD, lattice corneal dystrophy types I and III, granular corneal dystrophy and Reis-Bucklers dystrophy) might not be caused by mutation hot spots but by the founder effects.

Micro serial analysis of gene expression in normal human choroid and retinal pigment epithelial transcriptomes.

PURPOSE: To investigate the gene expression profile of the normal human choroid/retinal pigment epithelium(RPE) tissues. METHODS: Micro serial analysis of gene expression (Micro SAGE) was performed. A SAGE library was constructed from 110 microg of total RNA of normal human choroid/RPE tissue, and cloned tag concatemers transformed to E.coli were sequenced. The sequence data were analyzed by SAGE software and matched to GenBank and UniGene public databases. The sequence data were also compared with the choroid/RPE cDNA library of NEIBank. RESULTS: A total of 12 070 tags were sequenced; 3627 tags were unique. Of these 3627 tags, 2508 tags were encoded genes and 1119 tags were unknown tags in the UniGene database. The most frequently expressed tag was TCCCTATTAA, but the gene corresponding to this tag has not been identified yet. Other frequently expressed tags encoded a tissue inhibitor of matrix metalloproteinase 3, insulin-like growth factor binding protein-related protein 1, and transthyretin. These genes are notably different, with high expression frequencies when compared to the cDNA library of NEIBank. CONCLUSIONS: This gene expression profile of the normal human choroid/RPE tissue should provide further understanding of the biological function of the choroid and the pathogenesis of diseases in which the choroid and RPE play a role, such as choroidal neovascularization.

A novel missense mutation in a Japanese patient with gelatinous droplike corneal dystrophy.

PURPOSE: To report a novel missense mutation in TACSTD2 gene, L186P, responsible for gelatinous droplike dystrophy (GDLD). DESIGN: Case report and experimental study. METHOD: A 10-year-old Japanese boy suffering from typical GDLD was studied. A 1.1-kb DNA fragment of the TACSTD2 gene was amplified and analyzed using a molecular biological method. cDNA from the patient's cornea was also analyzed to determine which allele was expressed in the patient's corneal epithelium. RESULTS: Sequence analysis revealed that the patient is a compound heterozygote for the Q118X mutation and the L186P, the first missense mutation found in Japanese GDLD. Polymerase chain reaction-restriction fragment length polymorphism analysis from cDNA of patient's cornea revealed that the L186P missense mutation allele is expressed in the patient's corneal epithelium. CONCLUSION: We describe a novel mutation in one case of Japanese GDLD. The results confirm that the missense mutation L186P in the TACSTD2 gene is also responsible for the GDLD phenotype.

Allelic homogeneity due to a founder mutation in Japanese patients with lattice corneal dystrophy type IIIA.

Lattice corneal dystrophies (LCDs) are caused by mutations of the transforming growth factor beta-induced gene (TGFBI, formerly betaig-h3). LCD type IIIA (LCDIIIA) has been reported mostly from Japan. In this study, we demonstrate allelic homogeneity for Japanese patients with LCDIIIA, using intragenic polymorphic markers. When exon 11 of TGFBI was analyzed, all 18 patients examined were found to be heterozygous for both a P501T mutation and an IVS10-3C --> T variation. On the other hand, none of 54 normal Japanese control subjects had the P501T, and 5 of the controls were heterozygous for IVS10-3C --> T. Haplotype analysis of the patients revealed that both P501T and IVS10-3C --> T were located on the same chromosome, and a significant linkage disequilibrium (P < 0.001, Fisher's exact probability test) was observed between LCDIIIA (P501T) and IVS10-3C --> T. When exon 8 of the gene was analyzed, all these patients possessed the "G allele" of a 1028G/A polymorphism. A significant linkage disequilibrium (P < 0.003; chi-square test) was also observed between P501T and the G allele in the patients. These results suggest that allelic homogeneity seen in Japanese patients with LCDIIIA may result from a single founder mutation.

Effect of simultaneous oblique muscle surgery in foveal translocation by 360 degrees retinotomy.

PURPOSE: To assess the effect of simultaneous oblique muscle surgery during foveal translocation surgery with 360 degrees retinotomy in patients with neovascular maculopathy. METHODS: Foveal translocation with 360 degrees retinotomy was performed on 31 eyes of 31 patients with neovascular maculopathy (21 with age-related macular degeneration 9 with myopic neovascular maculopathy, and 1 with idiopathic neovascular maculopathy). All eyes had simultaneous torsional muscle surgery with recession of the superior oblique muscle and tucking of the inferior oblique muscle. Visual acuity, binocular vision, and degree of cyclotorsion were assessed pre- and postoperatively. The angles of retinal and global rotation, distance of foveal shift, and surgical complications were also investigated. RESULTS: With a mean postoperative follow-up of 10.0 months, vision improved (>0.2 log MAR units) in 13 eyes, was unchanged in 9 eyes, and worsened (>0.2 log MAR units) in 9 eyes. Ten of 31 eyes (32%) had a final visual acuity of 20/50 or better. Eleven patients had binocular fusion, 13 patients showed suppression, and 7 patients developed diplopia that was managed by spectacles with prisms or by secondary muscle surgery. The mean retinal and global rotations were 30.3 degrees and 23.7 degrees, respectively. The average size of the choroidal neovascular membrane was 1.3 disc diameters (DD), while the average shift of the fovea was 1.5 DD. After the primary surgery, six eyes developed retinal detachment, two eyes macular hole, and three eyes proliferative vitreoretinopathy. These complications were successfully managed by additional surgery. CONCLUSION: Foveal translocation with 360 degrees retinotomy is effective in restoring vision in 40% of patients with neovascular maculopathy. Simultaneous oblique muscle surgery was effective in rotating the globe by about 20 degrees, corresponding to to a foveal shift of 1.5 DD. While the development of torsional diplopia is generally prevented by simultaneous oblique muscle surgery, the relatively high incidence of surgical complications with this procedure should be taken into account.