Expanding the Phenotype of 8p23.1 Deletion Syndrome: Eight New Cases Resembling the Clinical Spectrum of 22q11.2 Microdeletion

Abstract

Objective: To report the effectiveness of early molecular diagnosis in the clinical management of rare diseases, presenting 8 patients with 8p23.1DS who have clinical features that overlap the phenotypic spectrum of 22q11.2DS.

Study design: This report is part of a previous study that aims to provide a precocious molecular diagnosis of the 22q11.2 deletion syndrome in 118 infants with congenital heart disease. To confirm the clinical diagnosis, patients underwent comparative genomic screening by the multiplex ligation-dependent probe amplification (MLPA) assay with the SALSA MLPA probemix kits P064-B2, P036-E1, P070-B2, P356-A1, and P250- B1. Subsequently, the patients performed the genomic microarray using the Infinium CytoSNP-850K BeadChip to confirm the deletion, determine the breakpoints of the deletion, and search for genomic copy number variations.

Results: MLPA performed with 3 different kits revealed the 8p23.1 typical deletion involving the PPP1R3B, MSRA, and GATA4 genes in the 5 patients. The array analysis was performed on these 5 patients and 3 other patients (8 patients) who also had clinical suspicion of 22q11 deletion (8 patients) allowed a precise definition of the breakpoints and excluded other genomic abnormalities.

Conclusions: Cytogenomic screening was efficient in establishing a differential diagnosis and ruling out the presence of other concomitant syndromes. The clinical picture of the 8p23.1 deletion syndrome is challenging; however, cytogenomic tools can provide an exact diagnosis and help to clarify the genotype-phenotype complexity of these patients. Our reports underline the importance of early diagnosis and clinical follow-up of microdeletion syndromes.