Dele？？o 22q11.2 em pacientes com defeito cardíaco conotruncal e fenótipo da síndrome da dele？？o 22q11.2

background: the 22q11.2 deletion syndrome is the most frequent human microdeletion syndrome. the phenotype is highly variable, being characterized by conotruncal heart defect, facial dysmorphisms, velopharyngeal insufficiency, learning difficulties and mental retardation. objective: the objective of this study was to investigate the frequency of deletion 22q11.2 in a brazilian sample of individuals with isolated conotruncal heart defect and 22q11.2 deletion syndrome phenotype. methods: twenty-nine patients were studied by classical cytogenetics, by fluorescence in situ hybridization (fish), and by molecular techniques. results: cytogenetic analysis by g-banding revealed a normal karyotype in all patients except one who presented a 47,xx,+idic(22)(q11.2) karyotype. using molecular techniques, a deletion was observed in 25% of the patients, all exhibiting a 22q11.2 deletion syndrome phenotype. in none of the cases the deletion was inherited from the parents. the frequency of 22q11.2 deletion was higher in patients with the clinical spectrum of the 22q11.2 deletion syndrome than in patients with isolated conotruncal heart defect. conclusion: investigating the presence of the deletion and its correlation with the patients' clinical data can help the patients and their families to have a better genetic counseling and more adequate clinical follow-up.