ABSTRACT
Background: Trisomy mosaicism of chromosome 5 is uncommon with few cases described. Case report: A 41-year-old woman underwent ultrasound (US) at 16 weeks, which showed oligohydramnios and intrauterine growth restriction (IUGR). Amniocentesis discovered a karyotype of 47,XX,+5/46,XX. US at 19 weeks disclosed IUGR, enlargement of right side of heart, main pulmonary artery dilatation, and a suspected congenital pulmonary airway malformation (CPAM) in the inferior lobe of the left lung. Due to poor fetal prognosis, the parents opted for legal termination of pregnancy. At postmortem, a wide ventricular septal defect and CPAM type 3 were found. Cytogenetic analyses on fetal tissues detected mosaic trisomy 5 in skin, thymus, kidneys and CPAM. Placenta and fetal peripheral blood revealed normal female karyotype. Discussion/conclusion: These results suggest that if a fetus presents normal phenotypic features, mosaicism may be confined to extraembryonic structures, otherwise, in case of malformations, it may be carried by affected organs.
Subject(s)
Cystic Adenomatoid Malformation of Lung, Congenital , Trisomy , Adult , Amniocentesis/methods , Chromosomes, Human, Pair 5 , Comparative Genomic Hybridization , Cri-du-Chat Syndrome , Female , Fetal Growth Retardation/diagnosis , Fetus , Humans , In Situ Hybridization, Fluorescence , Mosaicism , Pregnancy , Prenatal Diagnosis , Trisomy/diagnosis , Trisomy/genetics , Uniparental DisomyABSTRACT
OBJECTIVE: We present prenatal diagnosis of pseudomosaicism for trisomy 5 and a review of the literature of mosaic trisomy 5 at amniocentesis. CASE REPORT: A 39-year-old woman underwent amniocentesis at 17 weeks of gestation, which revealed a karyotype of 47,XY,+5[1]/46,XY[20]. The single colony with trisomy 5 had five metaphase cells, and all five cells had the karyotype of 47,XY,+5. Repeat amniocentesis performed at 20 weeks of gestation revealed a karyotype of 46,XY in 27/27 colonies. Simultaneously, interphase fluorescence in situ hybridization (FISH), array comparative genomic hybridization (aCGH), and quantitative fluorescent polymerase chain reaction (QF-PCR) were performed on uncultured amniocytes. Interphase FISH revealed no trisomy 5 in 100 uncultured amniocytes. aCGH revealed no genomic imbalance. QF-PCR excluded uniparental disomy 5. A healthy 3662-g male baby was delivered with a normal karyotype in cord blood and 3.75% (3/80 cells) of trisomy 5 cells in uncultured urinary cells compared with 0.95% (1/105 cells) of trisomy 5 cells in normal control examined by FISH at 1.5 months of age. A review of seven cases with mosaic trisomy 5 at amniocentesis shows that 4/7 had clinically normal outcome, 3/7 had structural defects, mainly the heart, 6/6 had normal karyotype in blood, and 2/3 had mosaic trisomy 5 in the fetal tissues. CONCLUSION: Prenatal diagnosis of mosaic trisomy 5 should alert the possibility of fetal structural abnormalities, especially the heart, and culture artifacts. We suggest that the application of molecular cytogenetic techniques such as aCGH, interphase FISH, and QF-PCR on uncultured amniocytes is useful in our understanding of the mosaic status at repeat amniocentesis.