200 patients were diagnosed with a new genetic panel designed for the clarification of the diagnosis of rare cancers

The Laboratory of Epigenetics of the Research Centre for Medical Genetics has developed a genetic panel that allows the rectification of the diagnosis of rare cancers as part of applied scientific research projects supported by the Russian Ministry of Science and Higher Education. Diagnoses were made for 200 people since the beginning of the use of a new genetic panel at the Research Centre for Medical Genetics, this is a significant number in the rare disease sphere.

Rare diseases include various phakomatoses: Legius syndrome, schwannomatosis, neurofibromatosis types 1 and 2. These diseases affect the skin, the nervous system, and patients develop various tumors, both benign and malignant. For example, neurofibromatosis type 1 can be represented by plexiform neurofibroma. All these diseases have similar clinical manifestations and the doctor cannot always make an accurate diagnosis based on the clinical picture. The spots that develop with Legius syndrome can be taken as a manifestation of neurofibromatosis, but this syndrome does not have such severe consequences as other diseases of this group, it does not require intensive treatment. In case of schwannomatosis, drugs that are prescribed for neurofibratomatoses will not have the desired effect. Accurate diagnosis is extremely important for the prognosis of the course of the disease and the choice of therapy.

The genetic panel developed in the Laboratory of Epigenetics of the Research Centre for Medical Genetics included 5 genes, mutations in which are responsible for the development of various phakomatoses. Today, NGS (next generation sequencing) types such as exome and genome sequencing are often used for DNA diagnostics. However, they do not provide sufficient depth of reading for targeted genes. It can be difficult to make a diagnosis if the patient has a mosaic genotype, when the pathogenic mutation is not present in all cells of the body. In this case, the studied sample may not contain sufficient number of molecules with mutations, which means that the cause of the disease may not be established. A small number of genes in the panel allows for deep sequencing and detection of mutations even in patients with a mosaic genotype. Mosaic cases in phakomatoses can be up to 30%, according to the laboratory. Accurate diagnosis is especially important for patients with neurofibromatosis type 1, as they are at high risk of developing plexiform neurofibroma. Today, a targeted drug has already been developed for treatment. It is available to patients under the age of 18 due to the “Krug Dobra” Foundation. However, the prescription of the drug requires molecular genetic confirmation of the diagnosis. The new genetic panel developed at the Research Centre for Medical Genetics will allow patients to obtain the confirmation of the diagnosis in the shortest possible time.