[Chromosome 22q11.2 microdeletion and phenotype analysis of patients with non-syndromic tetralogy of Fallot].

Objective: To investigate the frequency and clinical phenotypes of 22q11.2 microdeletion in patients with non-syndromic tetralogy of Fallot (TOF).

Methods: Six-eight non-syndromic TOF patients (38 males and 30 females, aged 0-11 years) were selected and evaluated by history, physical examination and review of medical records. After informed consent was obtained, peripheral blood was drawn for genomic DNA extraction. Chromosome 22q11.2 microdeletion was screened by multiplex ligation-dependent probe amplification (MLPA). Suspected cases were confirmed with fluorescence in situ hybridization (FISH). Data was analyzed with SPSS 11.5 software. Phenotype-genotype correlations were assessed using Fisher's exact test. P values less than 0.05 on a 2-sided test were considered to be significant.

Results: Six-eight non-syndromic TOF children were screened for a 22q11.2 deletion, among which 59 (86.8%) presented pulmonary stenosis (PS) and 9 (13.2%) presented pulmonary atresia (PA). Seven patients (10.3%) were found to have carried a deletion. Among these, four had TOF-PS, three had TOF-PA. The frequency of 22q11.2 deletion in patients with TOF-PA (3/9, 33.3%) is much higher than that of TOF-PS (4/59, 6.80%) (P< 0.05).

Conclusion: 22q11.2 microdeletion is present in approximately 10.3% of patients with non-syndromic TOF. The deletion tends to have a higher prevalence in patients with TOF-PA. 22q11.2 deletion should be screened in non-syndromic TOF children and genetic counselling may be provided.