Mrs Carmichael, 44, comes from a family affected by Fragile-X syndrome, the commonest inherited mental handicap in Britain. Two younger brothers and two cousins have it. Her brothers "are nice, happy chaps, but they can never lead normal lives," she said.
Because of the family history, Mrs Carmichael believed that although she is perfectly healthy and symptomless, there was a risk to any children she might have. At the time of her first pregnancy, no genetic tests were available for the condition but it was known that it affected mainly boys. Her first pregnancy was a male foetus. She decided on an abortion.
In the 1980s, a chromosome test became available: this could not discover whether she was a carrier of the defective gene, but it could be used during pregnancy. She now has two daughters aged 15 and 12, and completed her family in 1988 with the birth of a son.
Four years later, after a reliable test for carrier status was devised, Mrs Carmichael discovered she had not inherited the defective gene and had never been at risk of bearing children with the disease. She says the knowledge is "a tremendous relief - because of my own children. I was contemplating, when do I have to tell my children that they could be carriers?"
Her eldest daughter had already been asking questions, prompted by her uncles' condition, and Mrs Carmichael had warned her that when she had children in her turn there was a risk that they might be affected. Now that worry has been alleviated. "I know a lot of families who have the same anxieties about about how to tell their children that they are at risk of having children with the same sort of thing as their brothers and sisters," she said.
Mrs Carmichael worries that NHS genetics services "simply don't have the personnel or funding, so families do not have good follow-up". She knows of some who have had only the chromosome test and have not been recalled for the more reliable genetic test. Some women have decided not to have children, ignorant that a more modern test might clear them.Reuse content