A fertility watchdog in Britain, the Human Fertilisation and Embryology Authority (HFEA), has given approval for the extension of embryo screening to cover a wider range of mutated genes, in the main those which raise the risk of cancer in later life.
Meanwhile another proposal which would allow women to donate eggs for research has been put on hold to allow for consultations on whether women have been given sufficient information before giving consent.
The HFEA has ruled that pre-implantation genetic diagnosis, PGD, can now be used to reject embryos that carry a DNA mutation that predisposes carriers to illness in later life, such as breast and bowel cancer.
The ruling extends the range of inherited conditions that can be prevented by picking embryos that lack harmful genes, from those that will cause childhood diseases to now include those that are linked with late onset disease, but are not guaranteed to cause it.
But groundbreaking though the move may appear many critics are concerned and some oppose the ruling seeing it as the first step down the slippery slope of genetic engineering.
Dame Suzi Leather, the chairman of the HFEA, has rejected the criticism and maintains the approval relates only to serious genetic conditions for which there is a single gene test.
Leather says the decision does not open the door for wholesale genetic testing and the circumstances of each case will be carefully assessed.
The HFEA had previously only allowed PGD for inherited diseases such as cystic fibrosis and two cancers that affect young adults and children, and for an inherited type of eye and bowel cancer that conveyed a 90 percent increased risk.
The ruling means families with the inherited cancers can have embryos screened before transfer to the woman's womb to ensure they do not carry faulty genes that would predispose them to the illnesses.
Mutations in the BRCA1 and BRCA2 genes result in about an 80 percent risk of breast cancer while another faulty gene carries similar odds for a type of colon cancer. BRCA1 carriers have a 40 percent risk of suffering from ovarian cancer.
According to Leather the decision deals with serious genetic conditions for which there is a single test and the HFEA would not consider genetic screening for mild conditions such asthma or eczema or schizophrenia where a number of genes have been identified.
Leading fertility experts have welcomed the ruling and say any opportunity which prevents or reduces serious illness is a key component of good preventive medicine.