A Question of Health

My partner and I both carry the gene for sickle-cell disease. We are thinking of having children, but we are terribly worried about the possibility of producing a child with sickle-cell disease. Is it possible to have tests early in pregnancy to see if a child has the disease?

Q. My partner and I both carry the gene for sickle-cell disease. We are thinking of having children, but we are terribly worried about the possibility of producing a child with sickle-cell disease. Is it possible to have tests early in pregnancy to see if a child has the disease?

A. Sickle-cell disease (sometimes called sickle-cell anaemia) is a genetic condition that occurs when two parents, each of whom is usually a healthy person who carries one copy of the sickle-cell gene, have a child with two copies of the sickle-cell gene. A child with two copies of the gene will have sickle-cell disease, which can cause serious, and sometimes life-threatening, problems both in childhood and later in life. If two parents are carriers of the sickle-cell gene, there is a one-in-four (25 per cent) chance that each of their children will have sickle-cell disease. It is possible to have tests during the early part of pregnancy to see if a baby is affected by sickle-cell disease. This can be done within the first three or four months of pregnancy. However, if the baby is affected, parents then are faced with the agonising decision of whether to carry on with the pregnancy, or have an abortion. Before you get pregnant, you should get expert advice, either from a sickle-cell specialist or a clinical genetics centre. The Sickle Cell Society is a very good source of information about sickle-cell disease (tel: 020-8961 7795; net: www. sicklecellsociety.org).

Q. I recently had an X-ray taken of my spine because I have been suffering from chronic backache. The bones of the spine looked normal, but the X-ray showed that I have some small stones in both of my kidneys. I am now undergoing blood tests to try to find the cause of these kidney stones. What causes stones to form in the kidneys?

A. Some people seem to form stones in their kidneys and no cause can be discovered. But sometimes, an underlying condition is detected by blood or urine tests that explains why the stones are forming. One relatively common cause is a high level of calcium in the bloodstream. This can be due to an enlarged or overactive parathyroid gland (a tiny group of glands in the neck just near the thyroid gland). The parathyroid glands control the level of calcium in the blood. If they are producing too much parathyroid hormone, your calcium levels go up, and some of this calcium can be deposited in the kidneys in the form of stones. Kidney stones can also be caused by things like gout, excessive intake of vitamin D, and some kidney diseases. Whatever the cause of the stones, you can help yourself by drinking at least four pints of water a day.

Please send your questions to A Question of Health, 'The Independent', Independent House, 191 Marsh Wall, London E14 9RS; fax 020-7005 2182; or e-mail to health@ independent.co.uk. Dr Kavalier regrets that he is unable to respond personally to questions