Variability of CATCH-22 symptome complex within the framework of 22q11.2 deletion syndrome

Chromosomal pathology is one of the most common causes of congenital malformations. The CATCH-22 symptom complex is most often associated with a microdeletion of chromosome 22, upon detection of which it is customary to diagnose DiGeorge syndrome, a known primary immunodeficiency or syndrome of innate errors of immunity. According to our data on the frequency of occurrence among all chromosomal abnormalities, DiGeorge’s syndrome takes second place in the Sverdlovsk region after Down’s syndrome, but its diagnosis is not simple due to varying severity of clinical manifestations, as well as different forms of the chromosome 22 defects. Along with several typical variants of 22q11 microdeletions, there duplications of critical regions are also reported, accompanied by immunodeficiency and other symptoms of CATCH-22. The effectiveness of diagnosing chromosomal abnormalities both in pre- and postnatal period largely depends on the grouping criteria of the patients with suspected chromosomal abnormalities, and on the methods used to identify hereditary pathology. In our study, we analyzed and compared the results of studies of 23 patients with various rearrangements of the 22q11.2 region, which were observed by a geneticist and clinical immunologist. The paper presents data on the polymorphism of phenotypes associated with rearrangements of the 22q11.2 region with an analysis of pathomorphological manifestations depending on the type of structural anomaly, i.e, del22q11.2, or dup22q11.2. The results of analysis demonstrate importance of different diagnostic options for laboratory studies of microdeletion and microduplication syndromes associated with immune-dependent pathology. We also compared the results of molecular genetic diagnostics and phenotypic manifestations in deletions and duplications of the 22q11.2 region. To identify the rearrangements of 22q11.2 region, two different methods were used – Prenatal BoBs and multiplex ligase-dependent probes’ amplification (MLPA). In particular, the both methods were used in the same patient to verify diagnosis, thus enabling to show differences in their efficiency. It was concluded that 22q11.2 deletion syndrome exhibits wide heterogeneity in phenotypic traits: neurological and immunological manifestations, anomalies in musculoskeletal development and internal organs, skull deformities and facial dysmorphia. Each clinical case was unique, requiring careful analysis of clinical manifestations. It is necessary to have a wide range of laboratory options for molecular genetic verification of the diagnosis.