ROMA (ITALPRESS) – An international team coordinated by three Italian researchers — Viviana Cordeddu of the Istituto Superiore di Sanità, Marco Tartaglia of the Pediatric Hospital Child Jesus and Lucia Ziccardi of the Fondazione Bietti IRCCS — with the involvement of numerous European and US centers, identified the PRKCZ gene as the new genetic cause of retinite pigmentosa (RP), one of the most frequent hereditary diseases of retina and.
The study, published on Jama Ophthalmology, expands knowledge of the genetic and molecular basis of the disease. The retinite pigmentosa includes an extremely heterogeneous group of hereditary diseases of the retina, with onset both in pediatric and adulthood. The first signs can manifest with a marked difficulty to see in low light conditions, the so-called night blindness, and with a progressive reduction of peripheral vision.
With the progress of the disease, the field of vision can shrink to a characteristic tubular vision, in which the person mainly retains the central vision. A greater sensitivity to light and glare can also appear, a reduction in the ability to perceive contrasts and, in the most advanced forms and depending on the involvement of the central retina, a gradual reduction in visual acuity. Clinical evolution is however variable and depends on the specific genetic form and individual characteristics of the patient.
Through the sequencing of the genome of patients from different countries, researchers have identified pathogenic variants in the PRKCZ gene in ten families, demonstrating that alterations of this gene can cause a new form of retinitis pigmentosa. Most of the patients studied had a seemingly isolated form of the disease, with an adult onset. Q
this is particularly relevant because some forms of piegmentous retinite can occur many years after birth and, in the absence of an obvious family history, make the identification of the genetic cause more complex. The functional studies conducted by the research group also highlighted that the variants identified compromise the normal function of the PKC protein, involved in important cell processes.
The alterations of this protein can interfere with the mechanisms necessary for the maintenance and survival of photoreceptors, retinal cells responsible for the transformation of light into visual signals.
Identification of new genes associated with the disease can help improve the diagnostic path, allowing in some cases to connect the patient’s clinical picture to a specific genetic cause. It can also provide families with more precise information on the origin of the disease, the possible transmission mechanisms and the possible presence of other affected family members.
“Despite the extraordinary progress of genetics in recent years, Viviana Cordeddu, researcher of the Higher Institute of Health and the first author of the study, stresses a significant proportion of patients with retinite pigmentosa still remains without a molecular diagnosis. The identification of PRKCZ allows us to provide a response to new families and contributes to better understand the biological mechanisms underlying the degeneration of the retina”.
“The identification of new genes associated with retinite pigmentosa – says Marco Tartaglia, coordinator of the study and responsible for the Molecular Genetics and Functional Genomics Research Function of the Child Jesus Pediatric Hospital – is an important step forward in understanding the genetic bases and biological mechanisms underlying the disease. The discovery also opens up new perspectives for the development of more accurate diagnostic tools and future increasingly targeted therapies.”.
“Our Institute – adds Monica Varano, scientific director of the Bietti Irccs Foundation – was recognized as a reference centre for rare eye diseases and collaboration with the Iss and the Child Jesus Pediatric Hospital on these issues is long-standing.”.
The new discovery is also a starting point for further studies of the cell mechanisms involved in the degeneration of photoreceptors. The understanding of these mechanisms will contribute, in the long term, to the search for targeted therapeutic strategies, in a context in which gene therapy is affirmed as possible approach to different eye diseases. It is important to note that the identification of PRKCZ as a genetic cause of the disease does not correspond, at the moment, to the availability of a specific therapy for this form of pigment retinitis. The result is first of all an advance in the diagnosis and biological understanding of the disease, laying the foundations for future research activities.
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