Genetic background of congenital conotruncal heart defects--a study of 45 families.

Introduction: The latest achievements in molecular diagnosis create new possibilities for evaluation of congenital abnormalities.

Aim: To present our preliminary experience with genetic diagnosis of congenital combined conotruncal heart defects.

Methods: The analysis comprised 35 families with more than one member suffering from conotruncal heart defects (Group I) and 10 families (Group II) having a child with the clinical features of CATCH 22 syndrome. All family pedigrees were performed. Each patient was investigated by echocardiography to assess the diagnosis of the cardiac defect. Anamnestic information with regard to developmental milestones, learning abilities in childhood and psychiatric disorders were recorded. All individuals were qualified for further genetic molecular diagnostic procedures such as FISH analysis for microdeletion of chromosome 22q11 using probe N25 DiGeorge Region with 22qter control Direct CP 5141-DC.

Results: Based on the pedigree analysis in Group I we suggest that complex heart defects are transmitted as a recessive variant. None of the members of these families has the clinical features of CATCH 22 syndrome. In Group II we did not find familial predisposition for the appearance of congenital heart defects. None of the evaluated members of the families from Group I had microdeletion of chromosome 22q11 based on FISH analysis so we decided to isolate DNA for further molecular diagnosis. In group II in 6 (60%) individuals with typical features for CATCH 22 syndrome FISH analysis confirmed microdeletion of chromosome 22q11.

Conclusions: 1. The huge progress in molecular genetics creates new possibilities in the diagnosis of congenital heart defects. 2. The identification of families with high risk of recurrence of conotruncal heart defects enables genetic counselling and highly specialised medical care at the proper time.