Crispr technique and DNA
Congenital abnormalities place a heavy burden on individuals and the health care system
For the first time, scientists are able to engineer any part of the human genome with extreme precision using a revolutionary new technique called Crispr which has been likened to editing the individual letters on any chosen page of an encyclopedia without creating spelling mistakes. The landmark development means it is now possible to make the most accurate and detailed alterations to any specific position on the DNA of the 23 pairs of human chromosomes without introducing unintended mutations or flaws, scientists said
The development has been hailed as a milestone in medical science because it promises to revolutionise the study and treatment of a range of diseases, from cancer and incurable viruses to inherited genetic disorders such as sickle-cell anaemia and Down syndrome. hereditary diseases as Crispr technique heralds genetic revolution  . to revolutionise study and treatment of a range of diseases

Germline gene therapy on sperm, eggs or embryos to eliminate inherited diseases alters the DNA of all subsequent generations, but fears over its safety, and the prospect of so-called “designer babies”, has led to it being made illegal in Britain and many other countries.
The new gene-editing technique could address many of the safety concerns because it is so accurate. Some scientists now believe it is only a matter of time before IVF doctors suggest that it could be used to eliminate genetic diseases from affected families by changing an embryo’s DNA before implanting it into the womb.
“If this new technique succeeds in allowing perfectly targeted correction of abnormal genes, eliminating safety concerns, then the exciting prospect is that treatments could be developed and applied to the germline, ridding families and all their descendants of devastating inherited disorders,” said Dagan Wells, an IVF scientist at Oxford University.

Restriction enzymes: allowed scientists to cut the DNA molecule at or near a recognised genetic sequence. The enzymes work well in microbes but are more difficult to target in the more complex genomes of plants and animals. Their discovery in the 1970s opened the way for the age of genetic engineering, from GM crops to GM animals, and led to the 1978 Nobel Prize for medicine.
Polymerase chain reaction (PCR): a technique developed in 1983 by Kary Mullis  in California allowed scientists to amplify the smallest amounts of DNA – down to a single molecule – to virtually unlimited quantities. It quickly became a standard technique, especially in forensic science, where it is used routinely in analysing the smallest tissue samples left at crime scenes. Many historical crimes have since been solved with the help of the PCR test. Mullis won the Nobel Prize for chemistry in 1993.

By STEVE CONNOR in the Independent
Wednesday 06 November 2013