Prenatal diagnosis of a fetus with pure partial trisomy 1q32-44 due to a familial balanced rearrangement

We diagnosed a pure partial trisomy of the long arm of chromosome 1 in a fetus with multiple malformations detected prenatally. The father was a carrier of a balanced rearrangement involving 46,XY,inv(1)(qter→p36::q32→qter::p36→q32). The fetus had preaxial polydactyly, low-set ears, macrocephaly, a prominent forehead, a broad and flat nasal bridge, a small mouth, an arched palate, micrognathia and unilateral renal agenesis. The couple had previously an infant with the same phenotypic abnormalities. The aberration was initially detected on amniocentesis with GTG banding and was confirmed by fluorescence in situ hybridization (FISH). Our case and other published pure trisomy 1q32-44 cases showed similarities, which allowed the further delineation of the trisomy 1q syndrome. Copyright © 2002 John Wiley & Sons, Ltd.     

Outcome of prenatally diagnosed trisomy 6 mosaicism

We report the prenatal diagnosis of trisomy 6 mosaicism via amniocentesis, in which trisomy 6 cells were identified in three of five culture vessels with 33% (5/15) of colonies showing trisomic cells. The pregnancy was electively terminated and examination revealed minor abnormalities (shortening of the femurs, micrognathia, posterior malrotation of the ears, and bilateral camptomelia of the second digit of the hands and fifth digits of the feet). Cytogenetic analysis of the placenta showed trisomy 6 in 100% of 20 cells studied. Karyotype was 46,XX in 100 cells examined from fetal skin. There are relatively few prenatally diagnosed cases of mosaic trisomy 6 at amniocentesis. Confined placental mosaicism (CPM) has been postulated in other cases where follow-up cytogenetic studies were not available. The present case differs from those previously reported, as it appears to represent CPM of chromosome 6 with phenotypic effects to the fetus. Copyright © 2002 John Wiley & Sons, Ltd.     

Risk of amniocentesis in women screened positive for Down syndrome with second trimester maternal serum markers

In routine obstetrical practice, prior to offering invasive prenatal diagnosis, it is crucial to weigh the risks attendant on amniocentesis against the individual's risk of aneuploidy. We took advantage of a policy of follow-up of patients undergoing Down syndrome maternal serum screening to compare the rates of fetal loss before 24 weeks and of early premature delivery at 24–28 weeks between women who underwent amniocentesis and women who did not. A total of 54 902 patients entered the study, of whom 4039 (7.35%) were lost to follow-up and 387 were excluded because of a severe fetal abnormality. Of the 50 476 remaining patients, 3472 had an amniocentesis whereas 47 004 had not and served as controls. In the amniocentesis group, the fetal loss rate before 24 weeks was 1.12% (95% CI=1.08–1.15) and the 24–28 weeks premature delivery rate was 0.40% (95% CI=0.39–0.41) which was significantly higher than in controls (0.42% with 95% CI 0.41–0.43 and 0.24% with 95% CI 0.23–0.25, respectively). The 0.86% difference in adverse outcome rates between the amniocentesis and control groups may be attributable to amniocentesis and compares favourably with the positive predictive value of maternal serum markers (1.70%) observed in the present study. Copyright © 2002 John Wiley & Sons, Ltd.     

Evaluation of amniotic fluid cell filtration: An experimental approach to early amniocentesis

Prior to a prospective application of amniotic fluid (AF) cell filtration to early amniocentesis, we tested the technique on a surplus from mid-trimester samples. By using the same sample size of 5 ml in experiments with a filter and in routine diagnostic procedures (control), we evaluated an optimal filter system. The prolonged culture time of filtered cells and the reduced number of clones are most probably due to mechanical stress (filtration pressure), whereas loss of the cells by adhesion to the filter system, and an AF-free culture medium (growth factors) are suggested to be less important. The AF cells are very sensitive to mechanical stress. Slow filtration (⩽3 ml AF/min) through filters with a high porosity and the largest possible pore size should be preferred. A mixed cellulose ester filter membrane with a pore size of 5·0 μm proved to be the most efficient, allowing harvest of the filtered cells after only a slight prolongation of the culture time (+2·4 days) compared with unfiltered aliquots. A filter set with a bypass connected by three-way taps allows cell filtration during either aspiration or reinjection of the AF. Cell filtration after amniocentesis and consecutive reverse flushing of the membrane with the appropriate amount of culture medium proved to be the best with regard to easy handling and reducing the risk of bacterial contamination.     

Early genetic amniocentesis and its relationship to respiratory difficulties in paediatric patients: A report of findings in patients and matched controls 3–5 years post-procedure

This study evaluates the long-term pulmonary complications of 25 children from a prospective, matched-control, pilot study evaluating short-term complications of early (11–14 weeks' gestation) versus traditional (15 weeks' gestation and later) genetic amniocentesis. Five children in the early amniocentesis group were found to have various respiratory difficulties, a morbidity rate comparable to that of paediatric patients in the general population. These data identify the need for larger, multicentre trials.