Improving the Diagnosis of Children with 22q11.2 Deletion Syndrome: A Single-center Experience from Serbia.

ABSTRACT

Objective: The incidence of the 22q11.2 microdeletion among children who have at least two out of five major clinical criteria for 22q11.2 deletion syndrome. Design: Prospective study. Setting: University Children’s Hospital in Belgrade, Serbia between 2005 and 2014. Participants: 57 patients with clinical characteristics of 22q11.2 deletion syndrome. Methods: Standard G-banding cytogenetic analysis was performed in all children, and the 22q11.2 genomic region was examined using fluorescence in situ hybridization (FISH). For patients with no deletion detected by FISH, multiplex ligation-dependent probe amplification (MLPA) analysis was also done in order to detect cryptic deletions of this region and to analyze other genomic loci associated with phenotypes resembling the syndrome. A selected group of patients diagnosed to have 22q11.2 microdeletion by FISH underwent MLPA testing in order to characterize the size and position of deletion. Outcome Measure: The frequency of 22q11.2 microdeletion among children with at least two of the five major characteristics of 22q11.2 deletion syndrome (heart malformations, facial dysmorphism, T-cell immunodeficiency, palatal clefts and hypocalcemia/hypoparathyroidism) Results: Typical 22q11.2 microdeletion was detected in 42.1% of patients; heart malformation were identified in all of them, facial dysmorphism in 79.2%, immunological problems in 63.6%, hypocalcemia in 62.5% and cleft palate in 8.3%. Conclusions: A higher detection rate compared to one-feature criterion is obtained when at least two major features of 22q11.2 deletion syndrome are taking into consideration. The criteria applied in this study could be considered by centers in low-income countries.