Clinical and molecular description of the prenatal diagnosis of a fetus with a maternally inherited microduplication 22q11.2 of 2.5 Mb

Abstract

Microduplications of 22q11.2 have been recently characterized as a new genomic duplication syndrome showing an extremely variable phenotype ranging from normal or mild learning disability to multiple congenital defects and sharing some overlapping features with DiGeorge/Velocardiofacial syndrome (DGS/VCFS). We report on the prenatal diagnosis of a 22q11.2 microduplication in a fetus with normal development that was referred for chromosomal analysis at 17 weeks of gestation because of advanced maternal age. Pregnancy was the result of an IVF-ICSI attempt after 4 years of infertility, mainly due to severe oligoasthenoteratospermia of the father. Amniocentesis was undertaken and cytogenetic analysis revealed an apparently normal male karyotype. Multiple Ligation-dependent Probe Amplification (MLPA) revealed a microduplication in the 22q11.2 chromosome region. Parental analysis showed that the 22q11.2 microduplication has been inherited from the otherwise healthy mother. Analysis with high resolution array-CGH showed that the size of the microduplication is 2.5 Mb and revealed the genes that are duplicated, including the TBX1 gene. The parents elected to continue with the pregnancy and the infant is now five months old and shows normal development.

Keywords: 22q11.2; Array-CGH; CGH; CNVs; DGS/VCFS; Di George/Velocardiofacial syndrome; G bands Trypsin Giemsa; GTG; IVF-ICSI; MLPA; Microduplication; Multiple Ligation-dependent Probe Amplification; NAHR; Prenatal; comparative genome hybridization; copy number variations; in vitro fertilization- intracytoplasmic sperm injection; non-allelic homologous recombination.