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Milestone - 30,000 DNA samples from families with rare hereditary eye diseases

The Molecular Genetics Laboratory at the Department for Ophthalmology at the University Hospital Tübingen was founded 1992 and since then has collected and investigated - in large parts - the impressive number of 30,000 DNA samples from patients affected by rare hereditary eye diseases as well as their relatives.

There is a strong focus on Hereditary Retinal Diseases and Diseases of the Optic Nerve (optic atrophy and familial glaucoma). The number nees to be considered impressive because it these are so-called rare diseases, which are defined with less than one patient affected among 2,000 normal persons. Some diseases are so rare that only very few patients and families can be identified worldwide.

Each year the Molecular Genetics Laboratory banks about 1,200 DNA samples from blood samples but also DNA sent by clinicians and geneticists from Germany and abroad in the in-house biobank. Many patients are seen and remitted by the In-house Special Out Patient Clinic for Hereditary Rtinal Degenerations and Neuro-Ophthalmology, in which these patients are examined and supervised by experienced ophthalmologists for these rare disorders.

The biobank and database holds material and data from approximately 8,000 patients from over 6,000 families with Inherited Retinal Diseases. More than 1,000 of these are patients with achromatopsia, a rare congenital disorder in which patients suffer from severely reduced visual acuity, lack of color vision and strong light sensitivity and glare. In addition, DNA samples from over 2,000 patients with various forms of optic nerve disease (optic atrophy and Leber's hereditary optic neuropathy) are banked. The Tübingen Biobank for rare hereditary eye diseases thus needs to be considered among the TOP5 in Europe.

The samples in the biobank are used for research and to elucidate the genetic causes of these diseases, both at the Tübingen Institute for Ophthalmic Research, as well as through collaboration projects with other researchers and scientists in Germany and throughout the world. Ten 'disease genes' for hereditary eye diseases were discovered directly in Tübingen and eleven others were identified elsewhere using DNA samples from the Tübingen biobank. The biobank and its researchers are especially renowned for their work on the causes of achromatopsia, which led to the development of the world's first gene therapy study for CNGA3-achromatopsia in Tübingen. This project has also shown that the biobank and database is an important resource for the identification of patients for clinical trials, and especially for new therapy development.

Previously, only single candidate genes could be investigated using genetic methods. Today, all genes that are known for a particular disease (Panel sequencing), or even all human genes (Exome sequencing) can be examined simultaneously. In individual cases, even the entire genome of a human being (Genome sequencing) is now being investigated as part of research projects to identify the genetic cause.

While in the past a large proportion of patients with hereditary disorders remained unexplained, the technical advancements have improved so that - depending on the clinical diagnosis - 50-90% of all banked cases have already been solved, i.e. the suspected genetic cause of the disease in the families could be identified and the patients has received a genetic diagnosis.

Why is identifying the genetic cause important in such diseases? It serves to confirm the clinical diagnosis and to define the underlying mode of inheritance. The latter allows calculating the risk for relatives and children to be afflicted by the same disease. But most importang, almost all current therapeutic concepts rely on the exact knowledge of the molecular cause, since most concepts are currently based on the correction of the genetic defect or the replacement of the defective gene and protein.

Contact

Dr. Susanne Kohl
E-mail: susanne.kohl[at]uni-tuebingen.de

Prof. Dr. Bernd Wissinger
E-mail: wissinger[at]uni-tuebingen.de