Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New test can detect both genetic and chromosomal abnormalities in embryos

02.07.2009
One-step screening for both genetic and chromosomal abnormalities has come a stage closer as scientists announced that an embryo test they have been developing has successfully screened cells taken from spare embryos that were known to have cystic fibrosis.

They told a news briefing at the 25th annual meeting of the European Society of Human Reproduction and Embryology in Amsterdam today (Tuesday) that, as a result, they would be able to offer clinical trials to couples seeking fertility treatment later this year.

The researchers based in the USA and the UK have been able to prove that the technique, known as genome-wide karyomapping, was capable of not only detecting diseases caused by a specific gene mutation, in this case cystic fibrosis, but that it was also capable of detecting aneuploidy (an abnormal number of any of the 23 pairs of chromosome) at the same time. This is the first time they have been able to demonstrate that the test can work in cells taken from embryos that have already been diagnosed with the cystic fibrosis gene mutation using conventional preimplantation genetic diagnosis (PGD).

Gary Harton, PGD scientific director of the Genetics & IVF Institute in Fairfax, Virginia (USA) told a news briefing: "Karyomapping is a universal method for analysing the inheritance of genetic defects in the preimplantation embryo without any prior patient or disease specific test development, which often delays patient treatment. For the first time, the inheritance of both single gene defects and chromosomal abnormalities can be detected simultaneously at the single cell level. Unlike other methods, this is achieved entirely by analysing the DNA sequence at over 300,000 locations genome-wide in parents and appropriate family members, often children already affected by a disease, and comparing their sequence with that inherited by the embryo. This can be achieved very rapidly using current microchip technology known as microarray."

With karyomapping it is not necessary to know the exact DNA mutation that is being sought; the scientists just need to take the relevant chunk of DNA from the parent that carries the mutation somewhere along its length, and if it matches a chunk of DNA from the embryo, then they know the embryo has inherited the mutation. As karyomapping involves analysing chromosomes, it also detects the existence of aneuploidy at the same time.

"The range of applications is broad and includes single gene defects, abnormal chromosome number, structural chromosome abnormalities and HLA [human leukocyte antigen] matching in 'saviour sibling' cases," said Mr Harton.

Karyomapping was developed by Professor Alan Handyside of the London Bridge Fertility Gynaecology and Genetics Centre in London (UK), and Mr Harton has been providing samples and DNA information in order to test the method and validate it for use in the clinic.

"The hope is that clinicians will be able to test embryos for specific genetic diseases and know that, with one test, they are transferring chromosomally normal embryos. This will be a step forward from current technology that is mostly limited to choosing one test or the other," explained Prof Handyside.

Karyomapping would also be quicker and cheaper. Currently, developing a PGD test for a single gene defect can take weeks or months, as scientists have to identify the exact patient or disease-specific genetic mutation first before screening for it, which is labour-intensive and costly. By contrast, karyomapping can be carried out without such extended pre-test development; at present, it takes about three days, but Mr Harton and his colleagues believe this could be reduced to 18-24 hours.

In this most recent stage of their research they examined cells from five embryos that had been donated for medical research by a couple who had received successful fertility treatment, including PGD for cystic fibrosis. The embryos had developed to the blastocyst stage, which is about five days after fertilisation. Conventional PGD had already identified which embryos were unaffected, affected or were carriers of the disease. Karyomapping of cells from the donated embryos confirmed these diagnoses, but, in addition, it was able to identify which parent carried the affected chunk of DNA. Karyomapping also revealed two aneuploidies in two embryos, which had not been detected by the earlier PGD.

Mr Harton said: "This demonstrates that karyomapping, following genome-wide analysis of a single cell biopsied from embryos at the blastocyst stage, can provide highly accurate analysis for cystic fibrosis, combined with the detection of chromosomal aneuploidy. Now that vitrification [an improved method of embryo freezing] has improved embryo survival after thawing, it should be possible to vitrify embryos at the blastocyst stage, either before or after biopsy, and analyse the embryos for virtually any genetic disease and screen for aneuploidy of all 23 pairs of chromosomes simultaneously. This approach could make PGD by karyomapping less expensive than conventional single disease PGD because fewer embryos will be biopsied, more embryos will be chromosomally normal following growth to the blastocyst stage, and there is no need to custom develop tests for each disease or couple interested in PGD."

Prof Handyside concluded: "These tests have helped us to learn everything we can before we start to treat actual patients. I am confident that we will be offering a clinical trial to patients using karyomapping some time this year."

Mary Rice | EurekAlert!
Further information:
http://www.eshre.com

More articles from Life Sciences:

nachricht Immune Defense Without Collateral Damage
24.01.2017 | Universität Basel

nachricht The interactome of infected neural cells reveals new therapeutic targets for Zika
23.01.2017 | D'Or Institute for Research and Education

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Efficient time synchronization of sensor networks by means of time series analysis

24.01.2017 | Information Technology

Immune Defense Without Collateral Damage

24.01.2017 | Life Sciences

Open, flexible assembly platform for optical systems

24.01.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>