Prenatal Diagnosis of 18q Deletion Syndrome / 中山大学学报(医学科学版)

ObjectiveTo explore the prenatal diagnostic methods of 18q deletion syndrome and improve understanding on the value of non-invasive prenatal testing （NIPT） in prenatal diagnosis of 18q deletion syndrome. Methods18q deletion syndrome was detected by conventional methods such as serological screening， ultrasonic imaging examination， chromosome karyotype analyses of both amniotic fluid cells and parental peripheral blood， and molecular biological techniques including NIPT， chromosomal microarray analysis （CMA） and copy number variation sequencing （CNV-Seq）. Genetic counseling was conducted based on these examination results. ResultsNIPT identified a 24 MB deletion on the chromosome 18 which contained 17 genes including BCL2 by karyotype analysis of amniotic fluid cells and CMA. Further ultrasonic imaging examination confirmed the diagnosis of 18q deletion syndrome and karyotype analysis of parental peripheral blood revealed a de novo deletion mutation. ConclusionsInterventional prenatal diagnosis is an integral standard for the diagnosis of 18q deletion syndrome. NIPT， as an important screening test in middle pregnancy， can indicate the early possible chromosome segment deletion and reduce the time and economic cost when no abnormality is found in ultrasonic imaging.

A new mosaic der(18)t(1;18)(q32.1;q21.3) with developmental delay and facial dysmorphism / 소아과

We report the case of a 22-month-old boy with a new mosaic partial unbalanced translocation of 1q and 18q. The patient was referred to our Pediatric Department for developmental delay. He showed mild facial dysmorphism, physical growth retardation, a hearing disability, and had a history of patent ductus arteriosus. White matter abnormality on brain magnetic resonance images was also noted. His initial routine chromosomal analysis revealed a normal 46,XY karyotype. In a microarray-based comparative genomic hybridization (aCGH) analysis, subtle copy number changes in 1q32.1-q44 (copy gain) and 18q21.33-18q23 (copy loss) suggested an unbalanced translocation of t(1;18). Repeated chromosomal analysis revealed a low-level mosaic translocation karyotype of 46,XY,der(18)t(1;18)(q32.1;q21.3)[12]/46,XY[152]. Because his parents had normal karyotypes, his translocation was considered to be de novo. The abnormalities observed in aCGH were confirmed by metaphase fluorescent in situ hybridization. We report this patient as a new karyotype presenting developmental delay, facial dysmorphism, cerebral dysmyelination, and other abnormalities.