• to make informed judgements about the economic, social and ethical issues concerning embryo screening that they have studied or from information that is presented to them
• Embryos can be screened for the alleles that cause these and other genetic disorders’.

Some disorders are inherited:

• Huntington’s disease; a disorder of the nervous system is caused by a dominant allele of a gene and can therefore be passed on by only one parent who has the disorder
• Cystic fibrosis; a disorder of cell membranes must be inherited from both parents. The parents may be carriers of the disorder without actually having the disorder themselves. It is caused by a recessive allele of a gene and can therefore be passed on by parents, neither of whom has the disorder. (Attention is drawn to the potential sensitivity needed in teaching about inherited disorders.)