22q11 Copy Number Variations in a Brazilian Cohort of Children with Congenital Heart Disorders.

INTRODUCTION: Congenital heart disease (CHD) is the most common type of congenital defect reported to be one of the leading causes of mortality in the first year of life. Microdeletion and microduplication syndromes (MMS) are associated with cardiac malformations. Understanding which genetic factors are involved in these conditions directly impacts treatment decisions. We aimed to identify the occurrence of genetic alterations and their association with MMS in CHD pediatric patients evaluated in a reference service of Southern Brazil.

METHODS: Participants were recruited during 2010 in the intensive care unit of a pediatric hospital. MMs and regions of chromosome 22 were screened by SALSA MLPA Probemix P245 Microdeletion Syndromes-1A kit for detection of copy number variations (CNVs).

RESULTS: MMS were detected in 11 from 207 patients (5.3%). Heterozygous deletion in the 22q11.2 chromosome region was the most prevalent CNV (5 from 11 patients). Also, atypical RTDR1 deletion and 22q11.2 duplication were detected. MLPA was able to reveal microdeletions in SNRPN and NF1 genes in patients with a normal karyotype and FISH.

CONCLUSION: Our study reports the prevalence and variability of genomic alterations associated with MMS in CHD pediatric patients. The results by MLPA are of great help in planning and specialized care.