[Neurofibromatosis-1 microdeletion syndrome.]

Neurofibromatosis type 1 is a clinically extremely heterogeneous neurocutaneous disorder, inherited in autosomal dominant manner. It is primarily caused by intragenic loss-of-function mutations in the NF1 gene, however, as a result of improvements in molecular diagnostics, copy number variants affecting the NF1 gene and its flanking regions are increasingly being detected. Based on genotype-phenotype analyses, two groups can be distinguished: neurofibromatosis type 1 caused by point mutations and the so-called 17q11.2 microdeletion syndrome caused by microdeletions. Microdeletions are observed in 5-10% of cases and can be divided into four different types (type 1, 2, 3 and atypical) according to the size of the deletion, the genomic location of the breakpoints and the affected gene content. Patients with microdeletions often have a more severe course of the disease, with an increased risk of malignancies. With this review, which summarizes the main characteristics and molecular genetic background of neurofibromatosis-1 microdeletion syndrome, we would like to emphasize the importance of early diagnosis of patients with microdeletion syndrome and draw attention to the importance of close follow-up. Orv Hetil. 2022; 163(51): 2041-2051.