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PRAGUE: British researchers said Monday they had revolutionised a screening technique on embryos to help couples avoid the heartbreak of handing on a crippling inherited disease to their baby.
Five couples are expecting healthy babies as a result of their work, they said in research presented at a conference here of the European Society of Human Reproduction (ESHRE).
The technique amounts to a breakthrough in the search for an embryonic "fingerprint" -- a batch of genetic markers -- of diseases, such as muscular dystrophy and cystic fibrosis, that are caused by flaws in a single gene, they said.
This search, called pre-implantation genetic diagnosis, entails screening embryos that are created by in-vitro fertilisation.
At present, using a method introduced in the early 1990s, lab clinicians can only spot conditions where there is a glaring, well-known mutation in a single gene.
And in diseases that only affect males but not females, clinicians have to eliminate male embryos. This halves the number of embryos available for implantation in the uterus, which slashes chances of a successful pregnancy.
The new test, devised by doctors at the Center for Preimplantation Genetic Diagnosis at Guy's and St. Thomas' NHS Foundation Trust in London, entails testing parents and any existing children or relations to identify around about a dozen markers of the disease.
A cell is then taken from the embryo and then amplified a million times over to see if it carries these markers, and if so whether it carries two copies of them in its chromosomes.
The technique, called pre-implantation genetic haplotyping, fine-tunes the previous diagnostic tool, making it more accurate and allowing more embryos to be available for implantation.
In use for the past three months, it has been tested on embryos for Duchenne muscular dystrophy (DMD), a disease which means that both copies of chromosome 7 must carry a fault for a child to have the disease. Five successful pregnancies are underway, Guy's and St. Thomas' said in a press release.
"The development of this new approach for single-gene disorders represents a major step forward in widening the scope and availability of (embryonic gene testing) for serious diseases," the research, presented at the conference, said.
The team said they have already compiled a set of markers for cystic fibrosis; a blistering skin condition called junctional epidermolysis bullosa; a muscle-wasting disease called myotonic dystrophic; and Prader-Willi syndrome, characterised by short stature, mental retardation, flabby muscle and compulsive eating. - AFP/fa
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