Multiplex ligation-dependent probe amplification

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Multiplex ligation-dependent probe amplification (MLPA) is a variation of the multiplex polymerase chain reaction that permits amplification of multiple targets with only a single primer pair. [1] It detects copy number changes at the molecular level, and software programs are used for analysis. Identification of deletions or duplications can indicate pathogenic mutations, thus MLPA is an important diagnostic tool used in clinical pathology laboratories worldwide.

Contents

History

Multiplex ligation-dependent probe amplification was invented by Jan Schouten, a Dutch scientist. [1] The method was first described in 2002 in the scientific journal Nucleic Acid Research. [2] The first applications included the detection of exon deletions in the human genes BRCA1, MSH2 and MLH1, which are linked to hereditary breast and colon cancer. Now MLPA is used to detect hundreds of hereditary disorders, as well as for tumour profiling.

Description

Example of exon deletions detected by Multiplex ligation-dependent probe amplification in a Duchenne muscular dystrophy patient MLPA in GeneMarker.jpg
Example of exon deletions detected by Multiplex ligation-dependent probe amplification in a Duchenne muscular dystrophy patient

MLPA quantifies the presence of particular sequences in a sample of DNA, using a specially designed probe pair for each target sequence of interest. The process consists of multiple steps: [3]

  1. The sample DNA is denatured, resulting in single-stranded sample DNA.
  2. Pairs of probes are hybridized to the sample DNA, with each probe pair designed to query for the presence of a particular DNA sequence.
  3. Ligase is applied to the hybridized DNA, combining probe pairs that are hybridized immediately next to each other into a single strand of DNA that can be amplified by PCR.
  4. PCR amplifies all probe pairs that have been successfully ligated, using fluorescently labeled PCR primers.
  5. The PCR products are quantified, typically by (capillary) electrophoresis.

Each probe pair consists of two oligonucleotides, with sequence that recognizes adjacent sites of the target DNA, a PCR priming site, and optionally a "stuffer" to give the PCR product a unique length when compared to other probe pairs in the MLPA assay. Each complete probe pair must have a unique length, so that its resulting amplicons can be uniquely identified during quantification, avoiding the resolution limitations of multiplex PCR. Because the forward primer used for probe amplification is fluorescently labeled, each amplicon generates a fluorescent peak which can be detected by a capillary sequencer. Comparing the peak pattern obtained on a given sample with that obtained on various reference samples, the relative quantity of each amplicon can be determined. This ratio is a measure for the ratio in which the target sequence is present in the sample DNA.

Various techniques including DGGE (Denaturing Gradient Gel Electrophoresis), DHPLC (Denaturing High Performance Liquid Chromatography), and SSCA (Single Strand Conformation Analysis) effectively identify SNPs and small insertions and deletions. MLPA, however, is one of the only accurate, time-efficient techniques to detect genomic deletions and insertions (one or more entire exons), which are frequent causes of cancers such as hereditary non-polyposis colorectal cancer (HNPCC), breast, and ovarian cancer. MLPA can successfully and easily determine the relative copy number of all exons within a gene simultaneously with high sensitivity.

Relative ploidy

An important use of MLPA is to determine relative ploidy. For example, probes may be designed to target various regions of chromosome 21 of a human cell. The signal strengths of the probes are compared with those obtained from a reference DNA sample known to have two copies of the chromosome. If an extra copy is present in the test sample, the signals are expected to be 1.5 times the intensities of the respective probes from the reference. If only one copy is present the proportion is expected to be 0.5. If the sample has two copies, the relative probe strengths are expected to be equal.

Dosage quotient analysis

Dosage quotient analysis is the usual method of interpreting MLPA data. [4] If a and b are the signals from two amplicons in the patient sample, and A and B are the corresponding amplicons in the experimental control, then the dosage quotient DQ = (a/b) / (A/B). Although dosage quotients may be calculated for any pair of amplicons, it is usually the case that one of the pair is an internal reference probe.

Applications

MLPA facilitates the amplification and detection of multiple targets with a single primer pair. In a standard multiplex PCR reaction, each fragment needs a unique amplifying primer pair. These primers being present in a large quantity result in various problems such as dimerization and false priming. With MLPA, amplification of probes can be achieved. Thus, many sequences (up to 40) can be amplified and quantified using just a single primer pair. MLPA reaction is fast, inexpensive and very simple to perform.

MLPA has a variety of applications [5] including detection of mutations and single nucleotide polymorphisms, [6] analysis of DNA methylation, [7] relative mRNA quantification, [8] chromosomal characterisation of cell lines and tissue samples, [9] detection of gene copy number, [10] detection of duplications and deletions in human cancer predisposition genes such as BRCA1, BRCA2, hMLH1 and hMSH2 [11] and aneuploidy determination. [12] MLPA has potential application in prenatal diagnosis both invasive [13] and noninvasive. [14]

Recent studies have shown that MLPA (as well as another variants such as iMLPA) is a robust technique for inversion characterisation. [15]

Variants

iMLPA

Differences between MLPA and iMLPA MLPA iMLPA.png
Differences between MLPA and iMLPA

Giner-Delgado, Carla, et al. described a variant of MLPA combining it with iPCR. They call these new method iMLPA [15] and its procedure is the same as MLPA but there are necessary two additional steps at the beginning:

  1. First, a DNA treatment with restriction enzymes that cut on both sides of the region of interest is necessary.
  2. The fragments obtained from digestion are recircularized and linked

The probe design is quite similar. Each probe will be formed by two parts that have at least: a target sequence, which is a region that contains the sequence complementary to the region of interest, so that the correct hybridization can occur. And a primer sequence at the end, it is a sequence whose design varies and is what will allow the design of primers and subsequent fragment amplification. In addition, one of the parts of the probe usually contains a stuffer between the target sequence and the primer sequence. The use of different stuffers allows the identification of probes with the same primer sequences but different target sequences, that is key for multiple amplification of several different fragments in a single reaction.

The next step continues with the typical MLPA protocol. [1]

Related Research Articles

Polymerase chain reaction Laboratory technique to multiply a DNA sample for study

Polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it to a large enough amount to study in detail. PCR was invented in 1983 by the American biochemist Kary Mullis at Cetus Corporation. It is fundamental to many of the procedures used in genetic testing and research, including analysis of ancient samples of DNA and identification of infectious agents. Using PCR, copies of very small amounts of DNA sequences are exponentially amplified in a series of cycles of temperature changes. PCR is now a common and often indispensable technique used in medical laboratory research for a broad variety of applications including biomedical research and criminal forensics.

Reverse transcription polymerase chain reaction Laboratory technique to multiply an RNA sample for study

Reverse transcription polymerase chain reaction (RT-PCR) is a laboratory technique combining reverse transcription of RNA into DNA and amplification of specific DNA targets using polymerase chain reaction (PCR). It is primarily used to measure the amount of a specific RNA. This is achieved by monitoring the amplification reaction using fluorescence, a technique called real-time PCR or quantitative PCR (qPCR). Combined RT-PCR and qPCR are routinely used for analysis of gene expression and quantification of viral RNA in research and clinical settings.

In molecular biology, an amplicon is a piece of DNA or RNA that is the source and/or product of amplification or replication events. It can be formed artificially, using various methods including polymerase chain reactions (PCR) or ligase chain reactions (LCR), or naturally through gene duplication. In this context, amplification refers to the production of one or more copies of a genetic fragment or target sequence, specifically the amplicon. As it refers to the product of an amplification reaction, amplicon is used interchangeably with common laboratory terms, such as "PCR product."

Fluorescence <i>in situ</i> hybridization

Fluorescence in situ hybridization (FISH) is a molecular cytogenetic technique that uses fluorescent probes that bind to only particular parts of a nucleic acid sequence with a high degree of sequence complementarity. It was developed by biomedical researchers in the early 1980s to detect and localize the presence or absence of specific DNA sequences on chromosomes. Fluorescence microscopy can be used to find out where the fluorescent probe is bound to the chromosomes. FISH is often used for finding specific features in DNA for use in genetic counseling, medicine, and species identification. FISH can also be used to detect and localize specific RNA targets in cells, circulating tumor cells, and tissue samples. In this context, it can help define the spatial-temporal patterns of gene expression within cells and tissues.

Real-time polymerase chain reaction

A real-time polymerase chain reaction is a laboratory technique of molecular biology based on the polymerase chain reaction (PCR). It monitors the amplification of a targeted DNA molecule during the PCR, not at its end, as in conventional PCR. Real-time PCR can be used quantitatively and semi-quantitatively.

SNP genotyping is the measurement of genetic variations of single nucleotide polymorphisms (SNPs) between members of a species. It is a form of genotyping, which is the measurement of more general genetic variation. SNPs are one of the most common types of genetic variation. A SNP is a single base pair mutation at a specific locus, usually consisting of two alleles. SNPs are found to be involved in the etiology of many human diseases and are becoming of particular interest in pharmacogenetics. Because SNPs are conserved during evolution, they have been proposed as markers for use in quantitative trait loci (QTL) analysis and in association studies in place of microsatellites. The use of SNPs is being extended in the HapMap project, which aims to provide the minimal set of SNPs needed to genotype the human genome. SNPs can also provide a genetic fingerprint for use in identity testing. The increase of interest in SNPs has been reflected by the furious development of a diverse range of SNP genotyping methods.

Bisulfite sequencing Lab procedure detecting 5-methylcytosines in DNA

Bisulfitesequencing (also known as bisulphite sequencing) is the use of bisulfite treatment of DNA before routine sequencing to determine the pattern of methylation. DNA methylation was the first discovered epigenetic mark, and remains the most studied. In animals it predominantly involves the addition of a methyl group to the carbon-5 position of cytosine residues of the dinucleotide CpG, and is implicated in repression of transcriptional activity.

Digital polymerase chain reaction is a biotechnological refinement of conventional polymerase chain reaction methods that can be used to directly quantify and clonally amplify nucleic acids strands including DNA, cDNA, or RNA. The key difference between dPCR and traditional PCR lies in the method of measuring nucleic acids amounts, with the former being a more precise method than PCR, though also more prone to error in the hands of inexperienced users. A "digital" measurement quantitatively and discretely measures a certain variable, whereas an “analog” measurement extrapolates certain measurements based on measured patterns. PCR carries out one reaction per single sample. dPCR also carries out a single reaction within a sample, however the sample is separated into a large number of partitions and the reaction is carried out in each partition individually. This separation allows a more reliable collection and sensitive measurement of nucleic acid amounts. The method has been demonstrated as useful for studying variations in gene sequences — such as copy number variants and point mutations — and it is routinely used for clonal amplification of samples for next-generation sequencing.

Loop-mediated isothermal amplification (LAMP) is a single-tube technique for the amplification of DNA and a low-cost alternative to detect certain diseases. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) combines LAMP with a reverse transcription step to allow the detection of RNA.

Nucleic acid test Group of techniques to detect a particular nucleic acid sequence

A nucleic acid test (NAT) is a technique used to detect a particular nucleic acid sequence and thus usually to detect and identify a particular species or subspecies of organism, often a virus or bacterium that acts as a pathogen in blood, tissue, urine, etc. NATs differ from other tests in that they detect genetic materials rather than antigens or antibodies. Detection of genetic materials allows an early diagnosis of a disease because the detection of antigens and/or antibodies requires time for them to start appearing in the bloodstream. Since the amount of a certain genetic material is usually very small, many NATs include a step that amplifies the genetic material—that is, makes many copies of it. Such NATs are called nucleic acid amplification tests (NAATs). There are several ways of amplification, including polymerase chain reaction (PCR), strand displacement assay (SDA), or transcription mediated assay (TMA).

The versatility of polymerase chain reaction (PCR) has led to a large number of variants of PCR.

OLIGO Primer Analysis Software was the first publicly available software for DNA primer design. The first papers describing this software were published in 1989 and 1990, and consecutive upgrades in the 1990s and 2000s, all have been cited together over 600 times in scientific journals and over 500 times in patents. The program is a comprehensive real time PCR primer and probe search and analysis tool, and also does other tasks such as siRNA and molecular beacon searches, open reading frame and restriction enzyme analysis etc. It has been created and maintained by Wojciech Rychlik and Piotr Rychlik. The OLIGO has been reviewed several times in scientific journals, for the first time in 1991 in a review in Critical Reviews in Biochemistry and Molecular Biology, and for its next upgrades.

High Resolution Melt (HRM) analysis is a powerful technique in molecular biology for the detection of mutations, polymorphisms and epigenetic differences in double-stranded DNA samples. It was discovered and developed by Idaho Technology and the University of Utah. It has advantages over other genotyping technologies, namely:

Diversity arrays technology

Diversity Arrays Technology (DArT) is a high-throughput genetic marker technique that can detect allelic variations to provides comprehensive genome coverage without any DNA sequence information for genotyping and other genetic analysis. The general steps involve reducing the complexity of the genomic DNA with specific restriction enzymes, choosing diverse fragments to serve as representations for the parent genomes, amplify via polymerase chain reaction (PCR), insert fragments into a vector to be placed as probes within a microarray, then fluorescent targets from a reference sequence will be allowed to hybridize with probes and put through an imaging system. The objective is to identify and quantify various forms of DNA polymorphism within genomic DNA of sampled species.

Multiplex polymerase chain reaction refers to the use of polymerase chain reaction to amplify several different DNA sequences simultaneously. This process amplifies DNA in samples using multiple primers and a temperature-mediated DNA polymerase in a thermal cycler. The primer design for all primers pairs has to be optimized so that all primer pairs can work at the same annealing temperature during PCR.

Molecular Inversion Probe (MIP) belongs to the class of Capture by Circularization molecular techniques for performing genomic partitioning, a process through which one captures and enriches specific regions of the genome. Probes used in this technique are single stranded DNA molecules and, similar to other genomic partitioning techniques, contain sequences that are complementary to the target in the genome; these probes hybridize to and capture the genomic target. MIP stands unique from other genomic partitioning strategies in that MIP probes share the common design of two genomic target complementary segments separated by a linker region. With this design, when the probe hybridizes to the target, it undergoes an inversion in configuration and circularizes. Specifically, the two target complementary regions at the 5’ and 3’ ends of the probe become adjacent to one another while the internal linker region forms a free hanging loop. The technology has been used extensively in the HapMap project for large-scale SNP genotyping as well as for studying gene copy alterations and characteristics of specific genomic loci to identify biomarkers for different diseases such as cancer. Key strengths of the MIP technology include its high specificity to the target and its scalability for high-throughput, multiplexed analyses where tens of thousands of genomic loci are assayed simultaneously.

Polony sequencing is an inexpensive but highly accurate multiplex sequencing technique that can be used to “read” millions of immobilized DNA sequences in parallel. This technique was first developed by Dr. George Church's group at Harvard Medical School. Unlike other sequencing techniques, Polony sequencing technology is an open platform with freely downloadable, open source software and protocols. Also, the hardware of this technique can be easily set up with a commonly available epifluorescence microscopy and a computer-controlled flowcell/fluidics system. Polony sequencing is generally performed on paired-end tags library that each molecule of DNA template is of 135 bp in length with two 17–18 bp paired genomic tags separated and flanked by common sequences. The current read length of this technique is 26 bases per amplicon and 13 bases per tag, leaving a gap of 4–5 bases in each tag.

9q34 deletion syndrome is a rare genetic disorder. Terminal deletions of chromosome 9q34 have been associated with childhood hypotonia, a distinctive facial appearance and developmental disability. The facial features typically described include arched eyebrows, small head circumference, midface hypoplasia, prominent jaw and a pouting lower lip. Individuals with this disease may often have speech impediments, such as speech delays. Other characteristics of this disease include: epilepsy, congenital and urogenital defects, microcephaly, corpulence, and psychiatric disorders. From analysis of chromosomal breakpoints, as well as gene sequencing in suggestive cases, Kleefstra and colleagues identified EHMT1 as the causative gene. This gene is responsible for producing the protein histone methyltransferase which functions to alter histones. Ultimately, histone methyltransferases are important in deactivating certain genes, needed for proper growth and development. Moreover, a frameshift, missense, or nonsense error in the coding sequence of EHMT1 can result in this condition in an individual.

Recombinase polymerase amplification (RPA) is a single tube, isothermal alternative to the polymerase chain reaction (PCR). By adding a reverse transcriptase enzyme to an RPA reaction it can detect RNA as well as DNA, without the need for a separate step to produce cDNA,. Because it is isothermal, RPA can use much simpler equipment than PCR, which requires a thermal cycler. Operating best at temperatures of 37–42 °C and still working, albeit more slowly, at room temperature means RPA reactions can in theory be run quickly simply by holding a tube. This makes RPA an excellent candidate for developing low-cost, rapid, point-of-care molecular tests. An international quality assessment of molecular detection of Rift Valley fever virus performed as well as the best RT-PCR tests, detecting less concentrated samples missed by some PCR tests and an RT-LAMP test. RPA was developed and launched by TwistDx Ltd., a biotechnology company based in Cambridge, UK.

Johannes Petrus Schouten is a Dutch scientist, entrepreneur and philanthropist. He is the inventor of Multiplex-Ligation-dependent Probe Amplification (MLPA), a method for the research of genetic disorders. He founded the biotech company MRC Holland, based in Amsterdam and the MRC Holland Foundation.

References

  1. 1 2 3 Schouten JP, McElgunn CJ, Waaijer R, Zwijnenburg D, Diepvens F, Pals G (2002). "Relative quantification of 40 nucleic acid sequences by multiplex ligation-dependent probe amplification". Nucleic Acids Res. 30 (12): 57e–57. doi:10.1093/nar/gnf056. PMC   117299 . PMID   12060695.
  2. ↑ Schouten, Jan P.; McElgunn, Cathal J.; Waaijer, Raymond; Zwijnenburg, Danny; Diepvens, Filip; Pals, Gerard (2002-06-15). "Relative quantification of 40 nucleic acid sequences by multiplex ligation-dependent probe amplification". Nucleic Acids Research. 30 (12): e57. doi:10.1093/nar/gnf056. ISSN   0305-1048. PMC   117299 . PMID   12060695.
  3. ↑ "Multiplex Ligation-dependent Probe Amplification (MLPA)". Bitesize Bio. 2018-12-27. Retrieved 2021-06-07.
  4. ↑ Yau SC, Bobrow M, Mathew CG, Abbs SJ (1996). "Accurate diagnosis of carriers of deletions and duplications in Duchenne/Becker muscular dystrophy by fluorescent dosage analysis". J. Med. Genet. 33 (7): 550–558. doi:10.1136/jmg.33.7.550. PMC   1050661 . PMID   8818939.
  5. ↑ List of MLPA related articles Archived 2007-02-20 at the Wayback Machine
  6. ↑ Volikos E, Robinson J, Aittomaki K, Mecklin JP, Jarvinen H, Westerman AM, de Rooji FW, Vogel T, Moeslein G, Launonen V, Tomlinson IP, Silver AR, Aaltonen LA (2006). "LKB1 exonic and whole gene deletions are a common cause of Peutz‐Jeghers syndrome". J. Med. Genet. 43 (5): e18. doi:10.1136/jmg.2005.039875. PMC   2564523 . PMID   16648371.
  7. ↑ Procter M, Chou LS, Tang W, Jama M, Mao R (2006). "Molecular diagnosis of Prader-Willi and Angelman syndromes by methylation-specific melting analysis and methylation-specific multiplex ligation-dependent probe amplification" (PDF). Clin. Chem. 52 (7): 1276–1283. doi: 10.1373/clinchem.2006.067603 . PMID   16690734.
  8. ↑ Wehner M, Mangold E, Sengteller M, Friedrichs N, Aretz S, Friedl W, Propping P, Pagenstecher C (2005). "Hereditary nonpolyposis colorectal cancer: pitfalls in deletion screening in MSH2 and MLH1 genes". Eur. J. Hum. Genet. 13 (8): 983–986. doi: 10.1038/sj.ejhg.5201421 . PMID   15870828.
  9. ↑ Wilting SM, Snijders PJ, Meijer GA, Ylstra B, Van den IJssel PR, Snijders AM, Albertson DG, Coffa J, Schouten JP, van de Wiel MA, Meijer CJ, Steenbergen RD (2006). "Increased gene copy numbers at chromosome 20q are frequent in both squamous cell carcinomas and adenocarcinomas of the cervix". J. Pathol. 209 (2): 220–230. doi:10.1002/path.1966. PMID   16538612. S2CID   25427077.
  10. ↑ Introduction to MLPA
  11. ↑ Bunyan DJ, Eccles DM, Sillibourne J, Wilkins E, Thomas NS, Shea-Simonds J, Duncan PJ, Curtis CE, Robinson DO, Harvey JF, Cross NC (2004). "Dosage analysis of cancer predisposition genes by multiplex ligation-dependent probe amplification". Br. J. Cancer. 91 (6): 1155–1159. doi:10.1038/sj.bjc.6602121. PMC   2747696 . PMID   15475941.
  12. ↑ Gerdes T, Kirchhoff M, Lind AM, Larsen GV, Schwartz M, Lundsteen C (2005). "Computer-assisted prenatal aneuploidy screening for chromosome 13, 18, 21, X and Y based on multiplex ligation-dependent probe amplification (MLPA)". Eur. J. Hum. Genet. 13 (2): 171–175. doi: 10.1038/sj.ejhg.5201307 . PMID   15483643.
  13. ↑ Hochstenbach R, Meijer J, van de Brug J, Vossebeld-Hoff I, Jansen R, van der Luijt RB, Sinke RJ, Page-Christiaens GC, Ploos van Amstel JK, de Pater JM (2005). "Rapid detection of chromosomal aneuploidies in uncultured amniocytes by multiplex ligation-dependent probe amplification (MLPA)". Prenat. Diagn. 25 (11): 1032–1039. doi:10.1002/pd.1247. PMID   16231311. S2CID   23214645.
  14. ↑ Illanes S, Avent N, Soothill PW (2005). "Cell-free fetal DNA in maternal plasma: an important advance to link fetal genetics to obstetric ultrasound". Ultrasound Obstet. Gynecol. 25 (4): 317–322. doi: 10.1002/uog.1881 . PMID   15789415.
  15. 1 2 Giner-Delgado, C., Villatoro, S., Lerga-Jaso, J., Gayà-Vidal, M., Oliva, M., Castellano, D., ... & Olalde, I. (2019). Evolutionary and functional impact of common polymorphic inversions in the human genome. Nature communications, 10(1), 1-14. https://doi.org/10.1038/s41467-019-12173-x
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