Genotype and phenotype study of two patients with 22q11.2 deletion syndrome

Objective: To carry out genetic analysis for two patients affected with congenital heart disease, developmental delay with or without cleft palate.

Methods: Cytogenetic and molecular genetic methods including karyotyping, fluorescence in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA) and single nucleotide polymorphisms array (SNP-array) were employed to detect potential mutations. For parents of both patients, MLPA was used to analyze whether they were carrier of the deletion.

Results: For neither patient, no abnormality was detected upon karyotype analysis. However, FISH analysis has indicated the presence of 22q11.2 deletion. SNP-array analysis has confirmed that both patients have carried a 2.5 Mb deletion in the 22q11.2 region. MLPA analysis suggested none of the parents has carried the same deletion.

Conclusions: Although the phenotypes of our patients were not identical, they were both diagnosed as 22q11.2 deletion syndrome by multiple methods. The deletions in both cases were de novo in nature. Precise delineation of the genotype can facilitate better understanding of the patients' phenotype.