Prenatal diagnosis and molecular cytogenetic characterization of chromosome 22q11.2 deletion syndrome associated with congenital heart defects.

[22q11.2 deletion syndrome]

To report prenatal diagnosis of 22 q 11 .2 deletion syndrome in a pregnancy with congenital heart defects in the fetus .A 26 -year -old , primigravid woman was referred for counseling at 24 weeks of gestation because of abnormal ultrasound findings of fetal congenital heart defects . The Level II ultrasound revealed a singleton fetus with heart defects including overriding aorta , small pulmonary artery , and ventricular septal defect . Cordocentesis was performed . The DNA extracted from the cord blood was analyzed by multiplex ligation-dependent amplification (MLPA ). The MLPA showed deletion in the DiGeorge syndrome (DGS ) critical region of chromosome 22 low copy number repeat (LCR ) 22 -A ∼C . Conventional cytogenetic analysis revealed a normal male karyotype . Repeated amniocentesis and cordocentesis were performed . Whole-genome array comparative genomic hybridization (aCGH ) on cord blood was performed . aCGH detected a 3 .07 -Mb deletion at 22 q 11 .21 . Conventional cytogenetic analysis of cultured amniocytes revealed a karyotype 46 ,XY . Metaphase fluorescence in situ hybridization (FISH ) analysis on cultured amniocytes confirmed an interstitial 22 q 11 .2 deletion .Prenatal ultrasound findings of congenital heart defects indicate that the fetuses are at increased risk for chromosome abnormalities . Studies for 22 q 11 .2 deletion syndrome should be considered adjunct to conventional karyotyping . Although FISH has become a standard procedure for diagnosis of 22 q 11 .2 deletion syndrome , MLPA can potentially diagnose a broader spectrum of abnormalities , and aCGH analysis has the advantage of refining the 22 q 11 .2 deletion breakpoints and detecting uncharacterized chromosome rearrangements or genomic imbalances .