New macular findings in individuals with biallelic KLHL7 gene mutation.

OBJECTIVE: The ubiquitin-proteasome system pathway has been recognised as a crucial cellular mechanism for the proper function of photoreceptor cells. In particular, ubiquitin ligases (E3s) recognise and ubiquitinate specific proteins for degradation. The KLHL7 protein (a BTB-Kelch protein) has been found to play an important role in this process. There have been several reports that heterozygous mutations in the KLHL7 gene in adults are responsible for a rare cause of late-onset autosomal dominant retinitis pigmentosa with preservation of central vision and homozygous mutations in two young children, with Crisponi syndrome (CS)/cold-induced sweating syndrome type 1, result in a recessive form of early-onset peripheral retinal dystrophy type changes. The majority of children do not survive through to adulthood. The objective of this study is to report the visual symptoms and signs of two young adults clinically diagnosed with overlapping BOS/Cisproni syndrome, expanding the phenotypic presentation of KLHL7 gene mutations. METHODS AND ANALYSIS: This is a case report of the ophthalmic findings of two siblings with biallelic KLHL7 gene mutations. Siblings born to a non-consanguineous family and diagnosed with the overlapping clinical phenotype of Bohring-Opitz and and confirmed biallelic KLHL 7 gene mutation by whole exome sequencing were identified. Ophthlamic history and fundal examination was performed and analysed. RESULTS: Both patients had similar retinal findings. The fundus shows confluent hypopigmented/pale yellow lesions in the mid-periphery. The optic disc appears to be pale with a ring of atrophy and vessels appear attenuated. The macular of the younger patient shows a depigmented area around the fovea giving a bull's-eye appearance while the older sibling shows a fibrotic ring around the fovea suggesting a more advanced pathology. CONCLUSION: This paper expands the retinal phenotype to include a distinctive maculopathy in a recently described homozygous mutation in the KLHL7 gene in two young adults presenting with features that overlap the Bohring-Opitz syndrome and CS.

A Combined in silico, in vitro and Clinical Approach to Characterize Novel Pathogenic Missense Variants in PRPF31 in Retinitis Pigmentosa.

At least six different proteins of the spliceosome, including PRPF3, PRPF4, PRPF6, PRPF8, PRPF31, and SNRNP200, are mutated in autosomal dominant retinitis pigmentosa (adRP). These proteins have recently been shown to localize to the base of the connecting cilium of the retinal photoreceptor cells, elucidating this form of RP as a retinal ciliopathy. In the case of loss-of-function variants in these genes, pathogenicity can easily be ascribed. In the case of missense variants, this is more challenging. Furthermore, the exact molecular mechanism of disease in this form of RP remains poorly understood. In this paper we take advantage of the recently published cryo EM-resolved structure of the entire human spliceosome, to predict the effect of a novel missense variant in one component of the spliceosome; PRPF31, found in a patient attending the genetics eye clinic at Bristol Eye Hospital. Monoallelic variants in PRPF31 are a common cause of autosomal dominant retinitis pigmentosa (adRP) with incomplete penetrance. We use in vitro studies to confirm pathogenicity of this novel variant PRPF31 c.341T > A, p.Ile114Asn. This work demonstrates how in silico modeling of structural effects of missense variants on cryo-EM resolved protein complexes can contribute to predicting pathogenicity of novel variants, in combination with in vitro and clinical studies. It is currently a considerable challenge to assign pathogenic status to missense variants in these proteins.

Altered ratios of pro- and anti-angiogenic VEGF-A variants and pericyte expression of DLL4 disrupt vascular maturation in infantile haemangioma.

Infantile haemangioma (IH), the most common neoplasm in infants, is a slowly resolving vascular tumour. Vascular endothelial growth factor A (VEGF-A), which consists of both the pro- and anti-angiogenic variants, contributes to the pathogenesis of IH. However, the roles of different VEGF-A variants in IH progression and its spontaneous involution is unknown. Using patient-derived cells and surgical specimens, we showed that the relative level of VEGF-A165 b was increased in the involuting phase of IH and the relative change in VEGF-A isoforms may be dependent on endothelial differentiation of IH stem cells. VEGFR signalling regulated IH cell functions and VEGF-A165 b inhibited cell proliferation and the angiogenic potential of IH endothelial cells in vitro and in vivo. The inhibition of angiogenesis by VEGF-A165 b was associated with the extent of VEGF receptor 2 (VEGFR2) activation and degradation and Delta-like ligand 4 (DLL4) expression. These results indicate that VEGF-A variants can be regulated by cell differentiation and are involved in IH progression. We also demonstrated that DLL4 expression was not exclusive to the endothelium in IH but was also present in pericytes, where the expression of VEGFR2 is absent, suggesting that pericyte-derived DLL4 may prevent sprouting during involution, independently of VEGFR2. Angiogenesis in IH therefore appears to be controlled by DLL4 within the endothelium in a VEGF-A isoform-dependent manner, and in perivascular cells in a VEGF-independent manner. The contribution of VEGF-A isoforms to disease progression also indicates that IH may be associated with altered splicing. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The carboxyl terminus of VEGF-A is a potential target for anti-angiogenic therapy.

Anti-VEGF-A therapy has become a mainstay of treatment for ocular neovascularisation and in cancer; however, their effectiveness is not universal, in some cases only benefiting a minority of patients. Anti-VEGF-A therapies bind and block both pro-angiogenic VEGF-Axxx and the partial agonist VEGF-Axxxb isoforms, but their anti-angiogenic benefit only comes about from targeting the pro-angiogenic isoforms. Therefore, antibodies that exclusively target the pro-angiogenic isoforms may be more effective. To determine whether C-terminal-targeted antibodies could inhibit angiogenesis, we generated a polyclonal antibody to the last nine amino acids of VEGF-A165 and tested it in vitro and in vivo. The exon8a polyclonal antibody (Exon8apab) did not bind VEGF-A165b even at greater than 100-fold excess concentration, and dose dependently inhibited VEGF-A165 induced endothelial migration in vitro at concentrations similar to the VEGF-A antibody fragment ranibizumab. Exon8apab can inhibit tumour growth of LS174t cells implanted in vivo and blood vessel growth in the eye in models of age-related macular degeneration, with equal efficacy to non-selective anti-VEGF-A antibodies. It also showed that it was the VEGF-Axxx levels specifically that were upregulated in plasma from patients with proliferative diabetic retinopathy. These results suggest that VEGF-A165-specific antibodies can be therapeutically useful.

VEGF-A165b is an endogenous neuroprotective splice isoform of vascular endothelial growth factor A in vivo and in vitro.

Vascular endothelial growth factor (VEGF) A is generated as two isoform families by alternative RNA splicing, represented by VEGF-A165a and VEGF-A165b. These isoforms have opposing actions on vascular permeability, angiogenesis, and vasodilatation. The proangiogenic VEGF-A165a isoform is neuroprotective in hippocampal, dorsal root ganglia, and retinal neurons, but its propermeability, vasodilatatory, and angiogenic properties limit its therapeutic usefulness. In contrast, a neuroprotective effect of endogenous VEGF-A165b on neurons would be advantageous for neurodegenerative pathologies. Endogenous expression of human and rat VEGF-A165b was detected in hippocampal and cortical neurons. VEGF-A165b formed a significant proportion of total VEGF-A in rat brain. Recombinant human VEGF-A165b exerted neuroprotective effects in response to multiple insults, including glutamatergic excitotoxicity in hippocampal neurons, chemotherapy-induced cytotoxicity of dorsal root ganglion neurons, and retinal ganglion cells (RGCs) in rat retinal ischemia-reperfusion injury in vivo. Neuroprotection was dependent on VEGFR2 and MEK1/2 activation but not on p38 or phosphatidylinositol 3-kinase activation. Recombinant human VEGF-A165b is a neuroprotective agent that effectively protects both peripheral and central neurons in vivo and in vitro through VEGFR2, MEK1/2, and inhibition of caspase-3 induction. VEGF-A165b may be therapeutically useful for pathologies that involve neuronal damage, including hippocampal neurodegeneration, glaucoma diabetic retinopathy, and peripheral neuropathy. The endogenous nature of VEGF-A165b expression suggests that non-isoform-specific inhibition of VEGF-A (for antiangiogenic reasons) may be damaging to retinal and sensory neurons.

Mutational spectrum of the ZEB1 gene in corneal dystrophies supports a genotype-phenotype correlation.

PURPOSE: Mutations in ZEB1 have been reported in posterior polymorphous corneal dystrophy (PPCD3; MIM #609141) and Fuchs' endothelial corneal dystrophy (FECD6; MIM #613270). Although PPCD and keratoconus are clinically and pathologically distinct, PPCD has been associated with keratoconus, suggesting a common genetic basis. The purpose of our study was to perform mutational screening of the ZEB1 gene in patients affected with keratoconus or PPCD. METHODS: Sanger sequencing of ZEB1 was performed in 70 unrelated patients with keratoconus and 18 unrelated patients with PPCD. Real-time quantitative PCR (RT-qPCR) was performed on RNA from cultured corneal keratocytes obtained from a keratoconic patient harboring a missense ZEB1 mutation (p.Gln640His) undergoing corneal transplantation. RESULTS: Mutational analysis of ZEB1 in PPCD identified a previously reported frameshift mutation (C.1578_1579INSG) and a novel nonsense mutation (C.2249C A) in exon 7 of ZEB1 causing the insertion of a stop codon: p.Ser750X. In the keratoconus cohort, a novel heterozygous pathogenic mutation in exon 7 (c.1920G > T; p.Gln640His) of ZEB1 was identified in a family affected with keratoconus and Fuchs' endothelial corneal dystrophy. RT-qPCR performed on cultured corneal keratocytes harboring the missense ZEB1 mutation (p.Gln640His) demonstrated that COL4A1 and COL4A2 were markedly downregulated, and COL4A3, COL4A4, and COL8A2 were moderately downregulated. CONCLUSIONS: Our data combined with the previously reported mutational spectrum of ZEB1 support a genotypephenotype correlation: missense substitutions in the ZEB1 protein are associated with FECD6 and keratoconus, whereas protein truncating ZEB1 mutations result in PPCD3. The dysregulation of α-type IV collagens represents a common link between ZEB1 mutation and the clinical phenotypes (PPCD3, FECD, and keratoconus).

Tumor necrosis factor polymorphisms associated with tumor necrosis factor production influence the risk of idiopathic intermediate uveitis.

PURPOSE: Idiopathic intermediate uveitis (IIU) is a potentially sight-threatening inflammatory disorder with well-defined anatomic diagnostic criteria. It is often associated with multiple sclerosis, and both conditions are linked to HLA-DRB1*15. Previously, we have shown that non-infectious uveitis (NIU) is associated with interleukin 10 (IL10) polymorphisms, IL10-2849A (rs6703630), IL10+434T (rs2222202), and IL10+504G (rs3024490), while a LTA+252AA/TNFA-238GG haplotype (rs909253/rs361525) is protective. In this study, we determined whether patients with IIU have a similar genetic profile as patients with NIU or multiple sclerosis. METHODS: Twelve polymorphisms were genotyped, spanning the tumor necrosis factor (TNF) and IL10 genomic regions, in 44 patients with IIU and 92 population controls from the UK and the Republic of Ireland. RESULTS: IIU was strongly associated with the TNFA-308A and TNFA-238A polymorphisms. We found the combination of TNFA-308 and -238 loci was more strongly associated with IIU than any other loci across the major histocompatibility complex, including HLA-DRB1. CONCLUSIONS: TNF polymorphisms, associated with increased TNF production, are highly associated with IIU. These results offer the potential to ascribe therapeutic response and risk (i.e., the influence of HLA-DRB1*15 status and TNFR1 polymorphism) to anti-TNF therapy in IIU.

Autosomal dominant retinitis pigmentosa with intrafamilial variability and incomplete penetrance in two families carrying mutations in PRPF8.

PURPOSE: The aim of this study was to report detailed genotype/phenotype correlation in two British autosomal dominant retinitis pigmentosa (adRP) families with recently described mutations in PRPF8. METHODS: Ten affected members from the two families (excluded for PRPF31 mutations) were assessed clinically. Seven subjects had fundus photography; some had electrophysiology, autofluorescence imaging, and visual field testing. Linkage analysis was performed from genomic DNA in one family. RNA was extracted from lymphocytes of the proband from both families, reverse transcribed into cDNA and subsequently screened for mutations in PRPF8. Segregation of mutations in each family was tested by direct genomic sequencing of the specific exons carrying the mutation. RESULTS: All affected members complained of nyctalopia with variable age of onset. In the first family, there was marked variation in the clinical phenotype among affected individuals ranging from severe rod-cone dystrophy to a 67-year-old patient with a normal retinal appearance and mild rod dysfunction on scotopic electroretinography (ERG). The second family demonstrated similar variability and a history of a nonpenetrant individual. Linkage analysis in the first family showed strong evidence for linkage to markers on chromosome 17p implicating PRPF8 as a candidate gene. A c.6353 C>T change causing a nonconservative missense mutation p.S2118F was found in exon 38 of PRPF8 by direct sequencing of the cDNA. The mutation c.6930G>C (p.R2310S) was found in the second family. CONCLUSIONS: This is the first report of marked intrafamilial variability associated with mutations in the PRPF8 gene, including incomplete penetrance. PRPF8 mutations should be suspected in patients with adRP and variable expressivity.

Punctate inner choroidopathy and multifocal choroiditis with panuveitis share haplotypic associations with IL10 and TNF loci.

PURPOSE: The white-dot syndromes are a heterogenous group of chorioretinal disorders that have many common clinical features. Whether these disorders represent distinct clinical entities or different manifestations of the same disease warrants further interrogation. Two white-dot syndromes were investigated, with closely overlapping phenotypes--multifocal choroiditis with panuveitis (MFCPU) and punctate inner choroidopathy (PIC)--for differences in clinical course and genotype frequency at IL10 and TNF loci, known to be associated with noninfectious uveitis. METHODS: Twelve polymorphisms were genotyped, spanning the TNFA and IL10 genomic regions, in 61 patients with MFCPU or PIC and 92 population controls from the United Kingdom and Republic of Ireland. RESULTS: There were clear differences in clinical course between patients with MFCPU and PIC which had prognostic significance. However, both patient groups demonstrated similar associations with the IL10 haplotype, IL10htSNP2(-2849)AX/htSNP5(+434)TC and negative associations with the TNF haplotype, LTA+252A/TNFhtSNP1(-308)G/TNFhtSNP2(-238)G/TNFhtSNP3(+488)A/TNFd3. CONCLUSIONS: Despite clear differences in clinical course and outcome, MFCPU and PIC may still represent two manifestations of the same disease, given their similar genetic associations with IL10 and TNF loci, which are known to be associated with noninfectious uveitis and autoimmunity, in general. Definitive proof will necessitate genomewide sequence analysis. However, the data also support the notion that epigenetic factors have a strong effect on clinical phenotype.

Clinical and experimental advances in congenital and paediatric cataracts.

Cataracts (opacities of the lens) are frequent in the elderly, but rare in paediatric practice. Congenital cataracts (in industrialized countries) are mainly caused by mutations affecting lens development. Much of our knowledge about the underlying mechanisms of cataractogenesis has come from the genetic analysis of affected families: there are contributions from genes coding for transcription factors (such as FoxE3, Maf, Pitx3) and structural proteins such as crystallins or connexins. In addition, there are contributions from enzymes affecting sugar pathways (particularly the galactose pathway) and from a quite unexpected area: axon guidance molecules like ephrins and their receptors. Cataractous mouse lenses can be identified easily by visual inspection, and a remarkable number of mutant lines have now been characterized. Generally, most of the mouse mutants show a similar phenotype to their human counterparts; however, there are some remarkable differences. It should be noted that many mutations affect genes that are expressed not only in the lens, but also in tissues and organs outside the eye. There is increasing evidence for pleiotropic effects of these genes, and increasing consideration that cataracts may act as early and readily detectable biomarkers for a number of systemic syndromes.

Recombinant human VEGF165b inhibits experimental choroidal neovascularization.

PURPOSE: Vascular endothelial growth factor (VEGF-A) is the principal stimulator of angiogenesis in wet age-related macular degeneration (AMD). However, VEGF-A is generated by alternate splicing into two families, the proangiogenic VEGF-A(xxx) family and the antiangiogenic VEGF-A(xxx)b family. It is the proangiogenic family that is responsible for the blood vessel growth seen in AMD. METHODS: To determine the role of antiangiogenic isoforms of VEGF-A as inhibitors of choroidal neovascularization, the authors used a model of laser-induced choroidal neovascularization in the mouse eye and investigated VEGF-A(165)b effects on endothelial cells and VEGFRs in vitro. RESULTS: VEGF-A(165)b inhibited VEGF-A(165)-mediated endothelial cell migration with a dose effect similar to that of ranibizumab and bevacizumab and 200-fold more potent than that of pegaptanib. VEGF-A(165)b bound both VEGFR1 and VEGFR2 with affinity similar to that of VEGF-A(165). After laser injury, mice were injected either intraocularly or subcutaneously with recombinant human VEGF-A(165)b. Intraocular injection of rhVEGF-A(165)b gave a pronounced dose-dependent inhibition of fluorescein leakage, with an IC(50) of 16 pg/eye, neovascularization (IC(50), 0.8 pg/eye), and lesion as assessed by histologic staining (IC(50), 8 pg/eye). Subcutaneous administration of 100 microg twice a week also inhibited fluorescein leakage and neovascularization and reduced lesion size. CONCLUSIONS: These results show that VEGF-A(165)b is a potent antiangiogenic agent in a mouse model of age-related macular degeneration and suggest that increasing the ratio of antiangiogenic-to-proangiogenic isoforms may be therapeutically effective in this condition.

VEGF-A165b is cytoprotective and antiangiogenic in the retina.

PURPOSE: A number of key ocular diseases, including diabetic retinopathy and age-related macular degeneration, are characterized by localized areas of epithelial or endothelial damage, which can ultimately result in the growth of fragile new blood vessels, vitreous hemorrhage, and retinal detachment. VEGF-A(165), the principal neovascular agent in ocular angiogenic conditions, is formed by proximal splice site selection in its terminal exon 8. Alternative splicing of this exon results in an antiangiogenic isoform, VEGF-A(165)b, which is downregulated in diabetic retinopathy. Here the authors investigate the antiangiogenic activity of VEGF(165)b and its effect on retinal epithelial and endothelial cell survival. METHODS: VEGF-A(165)b was injected intraocularly in a mouse model of retinal neovascularization (oxygen-induced retinopathy [OIR]). Cytotoxicity and cell migration assays were used to determine the effect of VEGF-A(165)b. RESULTS: VEGF-A(165)b dose dependently inhibited angiogenesis (IC(50), 12.6 pg/eye) and retinal endothelial migration induced by 1 nM VEGF-A(165) across monolayers in culture (IC(50), 1 nM). However, it also acts as a survival factor for endothelial cells and retinal epithelial cells through VEGFR2 and can stimulate downstream signaling. Furthermore, VEGF-A(165)b injection, while inhibiting neovascular proliferation in the eye, reduced the ischemic insult in OIR (IC(50), 2.6 pg/eye). Unlike bevacizumab, pegaptanib did not interact directly with VEGF-A(165)b. CONCLUSIONS: The survival effects of VEGF-A(165)b signaling can protect the retina from ischemic damage. These results suggest that VEGF-A(165)b may be a useful therapeutic agent in ischemia-induced angiogenesis and a cytoprotective agent for retinal pigment epithelial cells.

Cytokine polymorphism in noninfectious uveitis.

PURPOSE: Noninfectious uveitis is a sight-threatening immune-mediated intraocular inflammatory disorder. The inheritance of uveitis in multiplex families and its association with known monogenic and polygenic immunologic disorders suggests that common genetic variants underlie susceptibility to uveitis as well as to other immunologic disorders. TNFA and IL10 are strong candidate genes, given the influence of these cytokines on inflammation, immune tolerance, and apoptosis. METHODS: The role of 12 polymorphisms spanning the TNFA and IL10 genomic regions was investigated in 192 uveitis patients and 92 population control subjects from four regional centers in the United Kingdom and Republic of Ireland. RESULTS: The results demonstrate that uveitis is associated with three haplotype-tagging SNPs (htSNPs) in the IL10 gene: htSNP2 (rs6703630), htSNP5 (rs2222202), and htSNP6 (rs3024490). IL10htSNP2AG/htSNP5TC was the most significantly associated haplotype (P = 0.00085), whereas the LTA+252AA/TNFhtSNP2GG haplotype was protective (P = 0.00031). Furthermore, subgroup analysis showed that the frequency of the TNFd4 allele was higher in patients with nonremitting ocular disease and/or those requiring higher levels of maintenance immunosuppression. Although these associations lost significance after Bonferroni correction, they infer a relationship that may be validated by a larger study. CONCLUSIONS: Since these variants are implicated in the susceptibility and severity of several immunologic disorders, the results support the hypothesis that common genetic determinants influence shared mechanisms of autoimmunity.

Does acute loss of vision in autosomal dominant optic atrophy occur early in childhood?

PURPOSE: In contrast to Autosomal dominant optic atrophy (ADOA), acute loss of vision is normally observed in Leber's hereditary optic neuropathy (LHON) patients. We present a case of a young child with ADOA with a confirmed OPA1 mutation who appeared to have had an acute visual loss in the third year of life. METHODS: Differentiating between ADOA and LHON requires careful documentation of visual symptoms, family history, clinical examination and genetic testing if available. CONCLUSIONS: This clarifies the clinical diagnosis, ensuring appropriate genetic counselling is provided so that affected individuals are accurately informed on inheritance patterns and implications for family members.

ß-Defensin 1 haplotype associated with postoperative endophthalmitis.

PURPOSE: Endophthalmitis is a rare but sight-threatening complication of intraocular surgery. ß-Defensins are antimicrobial peptides that appear to be important components of the ocular immune response. We propose that variation in defensin genes may alter susceptibility to endophthalmitis. METHODS: Post-cataract endophthalmitis patients (n = 28) and post-cataract controls (n = 75) were recruited and DNA samples extracted. The ß-defensin 1 gene (DEFB1) was screened for single-nucleotide polymorphisms (SNPs) using bidirectional sequencing. Case-control statistical assessment was undertaken for both the individual polymorphic loci observed and combined haplotypes using PHASE software. RESULTS: We identified 19 SNPs and observed strong linkage disequilibrium within the gene. We found that the three-SNP haplotype -688C/-44C/-20A was associated strongly with endophthalmitis [odds ratio (OR) = 8.88 (1.74, 45.42), corrected p = 0.0095]. Furthermore, we uncovered several trends, including increased prevalence of the -44CC genotype in the endophthalmitis group. CONCLUSION: We have shown previously that the -44CC SNP genotype was present in a single case of bilateral endophthalmitis. In this study, we found this genotype to be more common in the endophthalmitis group and a mini-haplotype including this SNP was associated strongly with endophthalmitis. There is functional evidence that this genetic profile decreases transcription of the ß-defensin 1 peptide and could therefore reduce the innate ocular immune defence.

Clinical phenotype of posterior polymorphous corneal dystrophy in a family with a novel ZEB1 mutation.

PURPOSE: To describe the clinical phenotype in a family with posterior polymorphous corneal dystrophy (PPCD) and a novel mutation in the ZEB1 gene. METHODS: Clinical examination, anterior segment photography, specular microscopy and electrophysiological investigations were performed and quantified. Genomic DNA extracted from peripheral blood was sequenced for ZEB1 exons. Cosegregation of identified mutation with the disease status in the family was confirmed using polymerase chain reaction and restriction fragment length polymorphism. RESULTS: Ocular examination was performed on five family members from two generations. Three had anomalies of the corneal endothelium that were consistent with PPCD. Endothelial cell counts ranged from 2306 to 2987 mm(2) (ref. 2000-4000 cells/mm(2) ). No evidence of glaucoma or retinal abnormalities was observed. Extraocular abnormalities such as inguinal herniation, hydrocoele and possible bony or connective tissue anomalies were part of the disease spectrum in this family. Mutation analysis revealed a novel change in exon 5 of ZEB1 (c.672delA) that cosegregated with the affected disease status. CONCLUSION: The detailed clinical features of PPCD associated with a novel ZEB1 mutation are supportive of the previously proposed range of phenotype parameters. Further phenotype-genotype correlations may provide insights into the clinical variability and pathological processes affecting the corneal endothelium, Descemet's membrane, retinal photoreceptor function and extraocular tissues of some patients.

A dominantly inherited mutation in collagen IV A1 (COL4A1) causing childhood onset stroke without porencephaly.

We describe a three generation family with recurrent strokes and cataracts. The index case, a 14 year old boy presented with stroke at the age of 14 years and again 6 months later. His mother had long standing episodic headaches diagnosed as migraine. Grandmother was initially diagnosed with multiple sclerosis and had recurrent strokes at age 18 years and 49 years. MRI scanning showed a diffuse leukoencephalopathy with microhaemorrhages in all three individuals. All of the family members had cataracts but did not have retinal arterial changes. Sequence analysis of COL4A1 revealed the heterozygous missense mutation c.2263G-->A in exon 30, responsible for a glycine-to-arginine substitution (p.Gly755Arg) in both the index case and mother. Grandmother died at the age of 73 years and DNA analysis was not possible. Mutation in COL4A1 should be considered in families with a history of autosomal dominant cerebral vasculopathy, even in the absence of porencephaly.

Expression of pro- and anti-angiogenic isoforms of VEGF is differentially regulated by splicing and growth factors.

Vascular endothelial growth factor A (VEGFA; hereafter referred to as VEGF) is a key regulator of physiological and pathological angiogenesis. Two families of VEGF isoforms are generated by alternate splice-site selection in the terminal exon. Proximal splice-site selection (PSS) in exon 8 results in pro-angiogenic VEGFxxx isoforms (xxx is the number of amino acids), whereas distal splice-site selection (DSS) results in anti-angiogenic VEGFxxxb isoforms. To investigate control of PSS and DSS, we investigated the regulation of isoform expression by extracellular growth factor administration and intracellular splicing factors. In primary epithelial cells VEGFxxxb formed the majority of VEGF isoforms (74%). IGF1, and TNFalpha treatment favoured PSS (increasing VEGFxxx) whereas TGFbeta1 favoured DSS, increasing VEGFxxxb levels. TGFbeta1 induced DSS selection was prevented by inhibition of p38 MAPK and the Clk/sty (CDC-like kinase, CLK1) splicing factor kinase family, but not ERK1/2. Clk phosphorylates SR protein splicing factors ASF/SF2, SRp40 and SRp55. To determine whether SR splicing factors alter VEGF splicing, they were overexpressed in epithelial cells, and VEGF isoform production assessed. ASF/SF2, and SRp40 both favoured PSS, whereas SRp55 upregulated VEGFxxxb (DSS) isoforms relative to VEGFxxx. SRp55 knockdown reduced expression of VEGF165b. Moreover, SRp55 bound to a 35 nucleotide region of the 3'UTR immediately downstream of the stop codon in exon 8b. These results identify regulation of splicing by growth and splice factors as a key event in determining the relative pro-versus anti-angiogenic expression of VEGF isoforms, and suggest that p38 MAPK-Clk/sty kinases are responsible for the TGFbeta1-induced DSS selection, and identify SRp55 as a key regulatory splice factor.