Can we rely on the multiplex ligation-dependent probe amplification method (MLPA) for prenatal diagnosis?

Abstract

Background: The major aneuploidies that are diagnosed prenatally involve the autosomal chromosomes 13, 18, and 21, as well as sex chromosomes, X and Y. Because multiplex ligation-dependent probe amplification (MLPA) is rapid and non-invasive, it has replaced traditional culture methods for the screening and diagnosis of common aneuploidies in some countries.

Objective: To evaluate the sensitivity and specificity of MLPA in a cross-sectional descriptive study for the detection of chromosomal aneuploidies in comparison to other methods.

Materials and methods: Genomic DNA was extracted from the peripheral blood samples of 10 normal controls and the amniotic fluid of 55 patients. Aneuploidies screening of chromosomes 13, 18, 21, X and Y were carried out using specific MLPA probe mixes (P095-A2). For comparison purposes, samples were also tested by Quantitative Fluorescent-PCR (QF-PCR) and routine chromosomal culture method.

Results: Using this specific MLPA technique and data-analyzing software (Genemarker v1.85), one case was diagnosed with 45, X (e.g. Monosomy X or Turner's Syndrome), and the remaining 54 cases revealed normal karyotypes. These results were concordant with routine chromosomal culture and QF-PCR findings.

Conclusion: The experiment demonstrates that MLPA can provide a rapid and accurate clinical method for prenatal identification of common chromosomal aneuploidies with 100% sensitivity and 100% specificity.

Keywords: Common aneuploidies; MLPA; Prenatal screening.

Figure 1

Image of amniotic fluid cells grown in Amniomax media after 15 days (Gibco, USA) ( Magnification 400X).To double check the results of MLPA obtained from the amniotic cells in the first day, they were grown and the experiment repeated with larger amount of cells and DNA

Figure 2

This is a part of the MLPA analysis report (Genemarker v1.85) of a normal disomic female and monosomic X female’s DNA, respectively. Normal relative probe signals are between the grey lines (0.7-1.3), and are depicted in green. Aberrant relative probe signals are depicted in red. The arrows indicate the eight chromosomes X signals, which all show a relative decrease in sample monosomic as compared to normal