Chromosome 22q11.2 deletion: world definition criteria, standards for diagnosis and monitoring

The article presents own clinical observation of the chromosome 22q11.2 microdeletion syndrome in a child with congenital heart disease. Phenotype also includes facial skull anomalies, immune disorders, developmental delay and even cognitive deficits. The authors analyzed the current world definition criteria, standards for diagnosis and monitoring of patients to diagnose this syndrome. The epidemiology of 22q11.2 deletion syndrome is determined in the work. Its incidence varies between 1 : 3,000–1 : 6,000 newborns, the inheritance is autosomal dominant, however, in Ukraine the syndrome is rarely diagnosed, which in our opinion is due to the lack of neonatal screening and insufficient awareness of physicians of clinical features of the disease. Section 22q11.2 is one of the most structurally complex regions of the genome, primarily through several large blocks. The locus of low copy repeats in region 22q11.2 is prone to a genetic error, which is due to 96% identity. Attention is focused that clinical manifestations vary with age. In young children, typical symptoms include a combination of congenital heart disease, immunodeficiency, malformation of the palate, hypocalcaemia, difficulty in feeding, delayed mental and speech development, behavioral disorders, kidney and genital abnormalities, laryngo-tracheo-esophageal malformations, hypothyroidism, skeletal dysmorphology. In some children, the disease manifests in school-age by behavio­ral anomalies and mental retardation, and hypocalcaemia. The presence of facial features can contribute to identifying the syndrome at any age. At the same time, difficulties in diagnosis are associated with widespread phenotypic variability. The article describes in detail the genetic diagnosis of the syndrome using several methods (fluorescence hybridization in situ, multiplex ligation-dependent probe amplification and chromosomal microarray), the choice of which depends on the period of life and the expressiveness of phenotypic traits. To monitor the child with the syndrome of chromosome 22q11.2 microdeletion, the authors describe approaches that include multidisciplinary team approach and system after system method.