Genetics and the Macular Dystrophies. George Anadiotis D.O. Medical Director Clinical and Biochemical Genetics Randall Children s Hospital

Transcription

1 Genetics and the Macular Dystrophies George Anadiotis D.O. Medical Director Clinical and Biochemical Genetics Randall Children s Hospital

2 Stargardt disease Best Vitelliform Macular Dystrophy North Carolina Macular Degeneration

3 Central macular scar with some pigmentary changes and perimacular flecks Fundus autoflorescence

4 ABCA4 Gene ATP binding cassette subfamily A member 4 Causes the most common type of Stargardt AR Also causes Fundus Flavimaculatus which is an allelic subtype of Stargardt Also causes a severe form of retinal dystrophy due to homozygous null mutations

5 ABCA4 mutations ABCA4 is produced in photoreceptors. Phototransduction leads to the formation of toxic byproducts and the job of the ABCA4 protein is to remove one of these substances, N retinylidene PE from the photoreceptor cells

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7 Gene Therapy Targeting DNA After 20 years of high profile failure, gene therapy is finally well on its way to clinical approval. It hasn t always been such high times for gene therapy, however. The field was booming in its early days, with approvals for gene therapy clinical trials rising exponentially from the first one in 1989 to 116 in But that year, gene therapy trial participant Jessie Gelsinger, a relatively healthy 18 year old who had an unusually mild form of liver disease caused by mutations in a gene on the X chromosome, died 4 days after receiving an injection of an adenovirus carrying an unmutated copy of the gene meant to correct his condition. The viral vector apparently triggered a massive immune response that caused multiple organ failure and brain death. Excerpt from The Scientist 2012

8 Gene Therapy Trial Occurring at Casey Eye Institute in Portland and at Hospital National des Quinze Vingt in Paris 9 patients with Stargardt, another 9 with atrophic age related macular degeneration Cells derived from human embryonic stem cellderived retinal pigment epithelium No adverse immune responses noted. Pts. are on immunosuppression Dose escalation currently in progress Dose injected into one eye with the other for control

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10 Gene Therapy Trial 72% (13 of 18) were noted to have patches of increasing subretinal pigmentation consistent with transplanted retinal pigment epithelium Best corrected visual acuity improved in ten eyes, remained the same in seven eyes and decreased by more than ten letters in one eye. Untreated eyes remained unchanged

11 Gene Therapy Trial Vision related quality of life issues increased for general and peripheral vision, and near and distance activities, improving by points 3 12 months after transplantation in patients with age related macular degeneration and 8 20 points in patients with Stargardt

12 Gene Therapy Concerns Limited number of patients The subretinal area is privileged, but will new areas still need continuing immunosuppression and for how long? The progression of these diseases has led to photoreceptor cell death. Can this treatment be combined with techniques to regenerate photoreceptors?

13 Generation of three dimensional retinal tissue with functional photoreceptors from human ipscs Xiufeng Zhong, Christian Gutierrez, Tian Xue, Christopher Hampton, M. Natalia Vergara, Li Hui Cao, Ann Peters, Tea Soon Park, Elias T. Zambidis, Jason S. Meyer, David M. Gamm, King Wai Yau & M. Valeria Canto Soler Nature Communications 5 Published 10 June 2014 Abstract Many forms of blindness result from the dysfunction or loss of retinal photoreceptors. Induced pluripotent stem cells (ipscs) hold great potential for the modelling of these diseases or as potential therapeutic agents. However, to fulfill this promise, a remaining challenge is to induce human ipsc to recreate in vitro key structural and functional features of the native retina, in particular the presence of photoreceptors with outersegment discs and light sensitivity. Here we report that hipsc can, in a highly autonomous manner, recapitulate spatiotemporally each of the main steps of retinal development observed in vivo and form three dimensional retinal cups that contain all major retinal cell types arranged in their proper layers. Moreover, the photoreceptors in our hipsc derived retinal tissue achieve advanced maturation, showing the beginning of outer segment disc formation and photosensitivity. This success brings us one step closer to the anticipated use of hipsc for disease modelling and open possibilities for future therapies.

14 Other Therapies ALK 001 is modified vitamin A, delivered orally, which prevents the formation of toxic vit A dimers in the eye Just completed phase one trials Double blind placebo controlled study currently underway. Dose is one capsule a day. Mouse models indicate that there is significant slowing of formation of ocular lipofuscin which is what contributes to visual loss.

15 home disorders genes tests laboratories clinics resources chiasmata Search Results Disorders (6) Genes (0) Tests (84) Laboratories (0) Clinics (0) Search Disorders... search Disorders - Results for STARGARDT Disorder Synonym(s) Related Ads Stargardt Disease, Autosomal Recessive OMIM Fundus Flavimaculatus Macular Degeneration, Juvenile Macular Dystrophy with Flecks Type 1 STGD1 Cardiac Disease Testing at GPS@WUSTL gps.wustl.edu/cardiac-disease Robust germline variant detection by NGS Variety of panels available Stargardt Disease 3 OMIM Stargardt Disease 4 OMIM Autosomal Dominant Macular Dystrophy Macular Dystrophy with Flecks Type 3 STGD3 Clinical Trial and Diagnostic Testing DDCclinic.org/laboratory Targeted Mutations for Amish Population Whole gene seq, NGS panels, quick TAT Stargardt Disease ABCA4-Related Stargardt Disease 1 OMIM ABCA4-Related Fundus Flavimaculatus ABCA4-Related Macular Degeneration, Juvenile ABCA4-Related Macular Dystrophy with Flecks Type 1 ABCA4- Related STGD1 Renal Disease Testing at GPS@WUSTL gps.wustl.edu/renal-disease NGS for Alport & Nephrotic Syndromes, ahus, metabolic disorders CNGB3-Related Stargardt Disease 1 OMIM CNGB3-Related Fundus Flavimaculatus CNGB3-Related Macular Degeneration, Juvenile CNGB3-Related Macular Dystrophy with Flecks Type 1 CNGB3- Related STGD1

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17 home disorders genes tests laboratories clinics resources chiasmata Cone-Rod Dystrophy NextGen Sequencing (NGS) Panel Full Gene Sequencing Clinical Research Prenatal Carrier Test Details Disorder Cone-Rod Dystrophy 7 Cone-Rod Dystrophy 11 Cone-Rod Dystrophy 13 X-linked Cone-Rod Dystrophy 3 Cone-Rod Dystrophy CERKL-Related Retinitis Pigmentosa Stargardt Disease, Autosomal Recessive Jalili Syndrome UNC119-Related Cone-Rod Dystrophy Cone-Rod Dystrophy 2 Cone-Rod Dystrophy 6 Cone-Rod Dystrophy 15 Cone-Rod Dystrophy 4 Cone-Rod Dystrophy 5 Cone-Rod Dystrophy 12 Choroidal Dystrophy, Central Areolar 2 PRPH2-Related Cone-Rod Dystrophy Cone-Rod Dystrophy 3 Cone-Rod Dystrophy 16 Cone Dystrophy 3 Cone-Rod Dystrophy 9 Type Molecular Panel Method Sequencing, Next Gen Genes ABCA4, ADAM9, AIPL1, C21orf2, C8orf37, CABP4, CACNA1F, CACNA2D4, CDHR1, CERKL, CNGB3, CNNM4, CRX, GUCA1A, GUCY2D, KCNV2, PDE6C, PITPNM3, PROM1, PRPH2, RAX2, RDH5, RIMS1, RPGRIP1, SEMA4A, UNC119 Ordering Test Code 1337 Test URL Turnaround

18 Best Vitelliform Macular Dystrophy Caused by the BEST1 gene and by PRPH2 gene Most cases caused by BEST1 PRPH2 mostly causes adult onset vitelliform MD In adults only about 25% of affected individuals will have mutations in one of these 2 genes for the rest cause is unknown AD inheritance

19 Lesion in the macula with areas of accumulation of lipofuscin

20 BEST1 gene Associated with the flow of chloride ions Mutations change the ion channel but how this actually results in buildup of lipofuscin and progressive loss of vision are still unknown

21 PRPH2 Produces a product known as peripherin 2 Peripherin 2 is involved in the stability of structures containing light sensitive pigments Abnormalities in this gene result in the degeneration of photoreceptors over time

22 NC Macular Dystrophy AD with highly variable expressivity Probable involvement of the PRDM13 gene (1/2016) PRDM13 gene is part of a gene family that controls gene expression during transcription