Spain has become the latest of a small number of countries to allow the genetic screening of embryos to check for certain types of cancer.It happened in the cases of two women undergoing fertility treatment. In one the screening was for a gene that causes breast cancer and in the other the test was for a thyroid cancer-causing gene. Health Minister Trinidad Jimenez described it as a breakthrough of enourmous importance that would give hope to couples who want to avoid an illness developing their child. In January a British woman became the first mother in the UK to give birth to a baby after embryo-screening for breast cancer. It is a highly controversial issue, particularly in Spain where there is strong Catholic opposition as the procedure involves discarding unviable embryos. The Catholic Church says it is akin to abortion.