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Biomedical subjects

Peter J Francis

Publications and source records attributed to Peter J Francis.

15 recordsLinked to original sources
PubMed2006

Photodynamic therapy of subfoveal choroidal neovascularization secondary to reticular pattern dystrophy: three-year results of an uncontrolled, prospective case series.

PURPOSE: To investigate the effects of photodynamic therapy (PDT) on subfoveal choroidal neovascularization (CNV) secondary to reticular pattern dystrophy (RPD) of the retinal pigment epithelium. DESIGN: Open-label, prospective, interventional case series. METHODS: Thirteen eyes diagnosed with subfoveal CNV associated with RPD were considered. Complete ophthalmic examinations were performed at baseline and thereafter at three-month intervals for three years. Primary outcome measure was the number of eyes with <15 letters loss (approximately <3 lines) at 12, 24, and 36 months, compared with baseline. Secondary outcome measures included CNV progression and number of PDT sessions. RESULTS: Seven eyes showed a decrease in best-corrected visual acuity of at least three lines at three-year examination. Each eye received a median number of treatments of two, zero, and zero in years one, two, and three, respectively. CONCLUSIONS: PDT does not appear to guarantee long-term vision stabilization in RPD-related subfoveal CNV, and alternative therapies should be investigated.

Aged↗
PubMed2006

Expanded genome scan in extended families with age-related macular degeneration.

PURPOSE: To investigate further the genetic contribution to age-related macular degeneration (AMD), increasing the power of a previous analysis and reproducing the original findings. METHODS: A large cohort of families with this condition was assembled, and an expanded genome scan was performed with 556 microsatellite markers. In 2003, the results were reported of a genome-wide linkage analysis of 70 of these pedigrees. Members of 51 new families have now been ascertained and many of the original pedigrees expanded. Parametric and nonparametric linkage analyses were performed with a denser map of markers. In addition, analyses were performed with the sample stratified by age at ascertainment and by two major advanced phenotypes for the disease: neovascular AMD (choroidal neovascularization) and geographic atrophy. RESULTS: The results corroborate the macular degeneration-susceptibility loci consistently reported by the authors and others in genome-wide scans. New loci were identified, including the finding of a two-point HLOD of 3.70 at 6q25.2. CONCLUSIONS: The results suggest that the use of families enriched in predisposition to AMD has legitimacy. Genetic analyses of a genome-wide scan performed on our large cohort of families add further confirmatory evidence that susceptibility loci lie on 1q, 3p, 9q, and 10q. Furthermore, new loci have been identified, including a locus on 6q.

Aged↗
PubMed2004

Genetics of childhood cataract.

PURPOSE OF REVIEW: Congenital cataracts, although much less common than their age-related counterparts, account for one-tenth of cases of childhood blindness. Approximately half are inherited, either in isolation or as part of a syndrome of ocular or systemic anomalies. This article reviews recent advances made in understanding the molecular genetic basis of isolated, nonsyndromic inherited cataract. RECENT FINDINGS: New disease-causing mutations continue to be identified and now encompass genes encoding a wide variety of different lens proteins. More detailed investigations of the functional consequences of each mutation are being reported and suggest that lens opacification results not only from precipitation and amyloid-like accumulation of proteins essential for lens transparency but also from interference with their secondary functions. SUMMARY: Improved functional characterization of mutations causing childhood cataract will improve understanding of lens development and physiology but will also have implications for the more common age-related cataract. This too has a significant genetic component to its etiology, and genes causing monogenic forms of childhood inherited cataract represent excellent candidate genes for age-related cataract. The identification of the genes conferring increased risk of developing age-related cataract will bring closer the development of a medical treatment to delay the onset of lens opacification and need for surgery.

Cataract↗
PubMed2003

Benign intracranial hypertension in children following renal transplantation.

Benign intracranial hypertension (BIH) is a condition characterized by headache, papilledema, and a raised cerebrospinal fluid pressure with normal cranial imaging. It is uncommon in childhood. Previously, there have been reports that children with chronic impairment of renal function may be at greater risk of developing BIH. This study involved retrospective case note analysis of children undergoing renal transplantation over the last 11 years at our institution. Nine children developed BIH after renal transplantation. The prevalence of the condition in our series was 4.4%. Several etiologically relevant risk factors were identified, including medication (nitrofurantoin, minocycline) and excess weight gain. Our results suggest that BIH may be a more frequent complication of the post-operative care of pediatric renal transplant recipients than previously thought. We hope to alert pediatric nephrologists that examination of the fundus for papilledema in all renal transplant patients complaining of headache is essential. If the diagnosis of BIH is delayed, irretrievable visual loss may not be avoided.

Adolescent↗
PubMed2003

Analysis of the ARMD1 locus: evidence that a mutation in HEMICENTIN-1 is associated with age-related macular degeneration in a large family.

Age-related macular degeneration (AMD) is a common cause of severe vision loss. Identification of the genes involved in AMD will lead to a better understanding of this disease at the molecular level, which will eventually lead to early detection, prevention and treatment. Previously, we mapped the ARMD1 gene to 1q25-31 in a large family with AMD. Here, we narrow the ARMD1 locus to 14.9 Mb between LAMB2 and D1S3469, a region containing 50 known genes. Twenty candidate genes within this region were screened for mutations. Only one DNA variation, an A16,263G transition in exon 104 of HEMICENTIN-1, was found to segregate exclusively with the disease haplotype in members of this large family with AMD. This variation produces a non-conservative substitution of arginine for glutamine at amino acid position 5345 (Gln5345Arg). It was also identified in 11 other individuals, all of whom share a haplotype, which envelops HEMICENTIN-1, with the large AMD family. The affected status of all but one of those individuals conforms to the age-dependent penetrance observed in AMD. The amino acid at position 5345 of HEMICENTIN-1 was conserved as glutamine in eight species analyzed. RT-PCR analysis demonstrated that exon 104 of HEMICENTIN-1 is alternatively spliced in various cell types. Exclusive segregation of Gln5345Arg with the disease haplotype in this large family, amino acid conservation of glutamine at this position among mammals, the non-conservative nature of the substitution and similarities to EFEMP1 support the conclusion that HEMICENTIN-1 is the ARMD1 gene.

Amino Acid Sequence↗
PubMed2003

Genetics of age-related macular degeneration.

Gene discoveries will lead to more effective them pies for AMD by identifying specific underlying disease mechanisms that might be corrected by drugs or gene therapy. For example, investigations are currently being carried out using pigment epithelium-derived factor (FEDF). The gene for this potent inhibitor of angiogenesis has been incorporated into an adenoviral vector and delivered into the eye by intravitreal injection to inhibit growth of new blood vessels in eyes with neovascular AMD. In the future, as the genetics of this complex disease are unraveled, more effective treatments and preventative measures that target specific molecular defects underlying the development of AMD can be expected.

Humans↗
PubMed2003

Gene therapy and control of angiogenesis.

The technology of gene therapy may be one step ahead of the present understanding of angiogenesis. The results of studies to modulate angiogenesis have been encouraging, however, and several of these studies are in the preclinical and clinical phases of testing. It is likely, therefore, that gene therapy for such diseases as diabetes mellitus and age-related macular degeneration will soon become a practical reality. It must be hoped that the lessons learned will be beneficial to others attempting to modulate angiogenesis in systemic disorders such as cancer and rheumatoid arthritis.

Eye↗
PubMed2001

A major marker for normal tension glaucoma: association with polymorphisms in the OPA1 gene.

Normal tension glaucoma (NTG) is a major form of glaucoma, associated with intraocular pressures that are within the statistically normal range of the population. OPA1, the gene responsible for autosomal dominant optic atrophy represents an excellent candidate gene for NTG, as the clinical phenotypes are similar and OPA1 is expressed in the retina and optic nerve. Eighty-three well-characterized NTG patients were screened for mutations in OPA1 by heteroduplex analysis and bi-directional sequencing. Sequences found to be altered in NTG subjects were examined for variations in 100 population controls. A second cohort of 80 NTG patients and 86 population controls was subsequently screened to determine whether the initial findings could be replicated. A single nucleotide polymorphism (SNP) on intervening sequence (IVS) 8 (IVS8 + 4 C/T) was found to be strongly associated with the occurrence of NTG in both cohorts (chi(2)=7.97, P=0.005 in the first cohort, chi(2)=9.93, P=0.002 in the second cohort; odds ratio 3.1 (95% CI: 1.8-5.6). A second SNP (IVS8 + 32 T/C) appeared to be associated with disease in the first cohort (chi(2)=4.71, P=0.030), but this finding could not be replicated in the second cohort. In the combined cohort, the compound at-risk genotype IVS8 + 4 C/T, + 32 T/C was strongly associated with the occurrence of NTG (chi(2)=22.04, P=0.00001 after correcting for testing four genotypes). These results indicate that polymorphisms in the OPA1 gene are associated with NTG and may be a marker for the disease.

Base Sequence↗
PubMedDate not supplied

Molecular genetic basis of inherited cataract and associated phenotypes.

Congenital cataract is a leading cause of visual disability in children. Inherited isolated (non-syndromic) cataract represents a significant proportion of cases and recently many causative genetic mutations have been identified. Inherited cataract is known to be clinically and genetically heterogeneous. Eleven clear-cut cataract phenotypes have been described. Cataract may be inherited as autosomal dominant, autosomal recessive, or X-linked recessive traits, and 12 loci and 15 specific genes associated with inherited isolated cataract have been identified to date; it is likely that more genes remain to be discovered. The identification of remaining genes will not only improve our understanding of the mechanism of cataract formation but will shed new light on the developmental biology and biochemistry of the lens. Furthermore, it is possible that some of these genes will be implicated in the more common age related cataract, which also has a genetic component to its etiology.

Cataract↗