Anne-Marie Lind

Computer-assisted prenatal aneuploidy screening for chromosome 13, 18, 21, X and Y based on multiplex ligation-dependent probe amplification (MLPA).

In routine prenatal diagnostics we used a commercial multiplex ligation-dependent probe amplification (MLPA) kit for aneuploidy screening for chromosomes 13, 18, 21, X and Y. We present the results of 1593 consecutive prenatal samples analysed and diagnosed prior to knowledge of the G-banding analysis during 8-month routine use of computer-assisted MLPA aneuploidy screening. In total, 27 aneuploidies were detected. There were no false positive results while two false negative results could be explained by a placental mosaicism and a partial monosomy, respectively. In total, 3.2% of the samples were inconclusive. We conclude that automatic computer assisted MLPA is a rapid, simple and reliable method for detection of aneuploidies in prenatal diagnostics.

Multiplex ligation-dependent probe amplification (MLPA) in prenatal diagnosis : experience of a large series of rapid testing for aneuploidy of chromosomes 13, 18, 21, X, and Y

Multiplex ligation‐dependent probe amplification (MLPA) is a relatively new method for rapid prenatal diagnosis of common aneuploidies, and larger series to evaluate its performance remain to be reported.

Visual classification of banded human chromosomes I. Karyotyping compared with classification of isolated chromosomes

Visual karyotyping and visual classification of isolated chromosomes was carried out by seven investigators on 22 trypsin banded metaphases of average quality. The karyotyping experiment resulted in an average error rate of 0-1% (zero-0-4%) and the classification of isolated chromosomes resulted in an error rate of 3% (2-5%). The B and F group chromosomes were found to be most difficult to classify when isolated, while no errors were made of the no. 1 and the X chromosome. Large differences were seen in the resulting error pattern for the individual investigators both with regard to their total error rate and also the chromosome types which they most frequently misclassified. Based upon these error patterns it is suggested that more than 95% of the chromosomes in an average quality material contain features upon which a reliable visual classification can be made. Thus there may be a potential possibility that these chromosomes may be classified by computer on the basis of these features. The fact that visual karyotyping is much more reliable than visual classification of isolated chromosomes indicated that computer classification of chromosomes should include programming capable of making appropriate comparison between the chromosomes in the metaphase and at the same time take into account the expected presence of 23 chromosome pairs for normal cells. This would simulate the human performance of visual karyotyping and make a classification possible of at least some of the remaining 5% difficult chromosomes.

Diagnostic yield by supplementing prenatal metaphase karyotyping with MLPA for microdeletion syndromes and subtelomere imbalances.

The aim of the study was to retrospectively assess the relevance of using multiplex ligation‐dependent probe amplification (MLPA) for detection of selected microdeletion syndromes (22q11, Prader–Willi/Angelman, Miller–Dieker, Smith–Magenis, 1p‐, Williams), the reciprocal microduplication syndromes and imbalance at the subtelomere regions of chromosomes in a routine prenatal setting.

A case of first trimester chromosomal mosaicism confined to the cultivation of the gestational products

The advantages of the emergence and developmcnt of chorionic villi sampling (CVS) for early prenatal diagnosis are evident, but there are a host of new diagnostic problems caused by the use of extraembryonic tissues. We report a case in which 45X/46XY mosaicism was diagnosed by cultivation of chorionic villi and fetal cells. Direct chromosomal preparations of chorionic villi failed to diagnose the abnormality.