Background
Galactosaemia literally means 'galactose in the blood'. Galactose is a sugar which mainly comes from lactose, the sugar found in milks. Lactose is normally broken down into the two simple sugars, galactose and glucose. The galactose is then broken down further and used in many parts of the body including the brain. In Galactosaemia it cannot be broken down completely and used because of deficiency or absence of an enzyme, galactose-1-phosphate uridyl transferase or Gal-1-PUT. Galactose, galactose-1-phosphate and other harmful chemicals build up and lead to the serious illness that occurs in the first few weeks of life once the baby is fed on milk containing lactose. It is a lifelong condition. What Causes Galactosaemia?
The enzyme is deficient or absent because of a mistake or mutation in the genetic code. Our chromosomes are made of something called DNA. They carry a coded message, rather like a computer programme that makes us what we are, for example giving us a particular hair colour. We have two copies of all our chromosomes (except the sex chromosomes) and therefore our genes. We inherit one copy from our mother and one from our father. In Galactosaemia the child inherits a mistake or mutation from both parents, which codes for the enzyme Gal-1-PUT. They can't therefore make enough Gal-1-PUT to break down galactose in the diet. The parents are perfectly healthy because they have one normal gene which allows them to make enough of the enzyme to keep them healthy. A parent doesn't know they carry the disorder until they have an affected child. In each and every pregnancy there is a 1:4 chance of having another affected baby.

We can look for the genetic mistake (or mutation) in the DNA, and when we do this we find that in quite a high proportion of children there is the same mutation. We are frying to look to see whether the mutation is related in any way to the sorts of problems that children with Galactosaemia have, but at the moment there only seems to be a loose association between the mutation and outcome of affected children.

How Common is Galactosaemia?
Galactosaemia is rare but it is still common enough for paediatricians and biochemists to understand a lot

Making the Diagnosis
Someone with Galactosaemia is unable to break down and use (metabolise) galactose. The main dietary source of galactose is lactose which is found in milks. This is why the baby becomes unwell usually in the first week having appeared completely normal at birth. Galactose and galactose 1 phosphate levels rise in the baby's blood and he/she becomes ill. Signs of liver disease including jaundice, lethargy, poor feeding, and weight loss are very common. The severity of the liver disease varies a lot. Babies can also be prone to infection at this stage, although this does not continue to be a problem. Cataracts may also be present. These symptoms are not just seen in Galactosaemia and the paediatrician looking after your baby will do a range of tests to make the diagnosis. The diagnosis is made by measuring the enzyme level in your baby's blood. If he/she has been given a blood transfusion your doctor may need to take blood from both parents to make the diagnosis.

Once the galactose-free diet has been started the liver disease will disappear and the baby will start to gain weight normally. Over time the cataracts will also disappear.

What is the Treatment for Galactosaemia?
The most important part of the treatment is to exclude galactose from the diet for the rest of the child's life. The main source of this in the diet is lactose in milk and milk products. This means that people with Galactosaemia have a special milk and do not have butter, cheese and any milk products such as milk protein which has different names such as whey protein or casein which contain Lactose. Lactose and milk products are added to many processed foods and even medicines so you need to find out what is in them before giving them. This sounds very difficult at first but you will be in dose touch with a dietician who will always be able to help if you need to check anything. Information and lactose free food lists are available from the individual support groups of many of the countries involved in the European Galactosaemia Society. You will become confident at dealing with the diet and remember help is always available.

It is a diet for life.

What will happen once the Baby is on the Diet?
The paediatrician will make sure the liver disease and the cataracts have disappeared completely and will then make sure that your baby grows normally. There should be no long term liver or eye problems. He/she will need regular medical and developmental checks which will be organised for you. At first these appointments will be quite often but gradually they will be less frequent.

Other than excluding galactose (and some care needs to be taken with medicines used regularly) the baby, child and adult with Galactosaemia can be treated as completely normal. If a medicine needs to be given urgently for a serious illness the possibility of the medicine containing lactose is less important than the illness being treated. Immunisations should be given at the normal time.

Long Term
Unfortunately some children develop speech and language and/or learning difficulties, especially in maths and science. We are not entirely sure whether this is because of some damage which may have occurred in the womb (this is no fault of the mother), or whether it is because all of us make a small amount of galactose in our own bodies. This then affects the brain but does not cause the liver disease to recur.

There is no way of preventing this at present. The speech and language difficulties consist mainly of problems with organising speech, and the term used for this is oromotor dyspraxia. There may also be problems with movements which is called motor dyspraxia. This leads to slowness in completing tasks.

There seems to be no clear association between how ill your baby was initially or how quickly the diagnosis was made, and the chance of developing these neurological difficulties. We do not understand why one child has more problems than another. Although we cannot undo these difficulties, by picking them up early we can try to minimise the effect they have on your child's education and social interactions. For this reason assessments will often be carried out if there are any worries.
In addition to these neurological problems, many girls do not go into puberty at the right time, or having started their periods may stop having them. There are galactosaemic women though who have had babies. The baby is not affected by the mother's galactosaemia. Unfortunately however galactosaemia does seem to affect the ovaries and women may be infertile or have reduced fertility. There may be ways of getting around this in the future but even now women can have IVF using donated eggs. All girls are kept under review and if puberty doesn't happen at the right age medicine a little like hormone replacement treatment can be given. This will be done very carefully and puberty will progress at the same rate as in a girl who has gone into puberty naturally. You will be kept up to date with any new information on fertility treatment by your doctor.

Possibly related to the hormonal problems, but also due to the diet, older patients may develop osteoporosis. As dietary factors are important, boys can be affected by this just like girls although it is likely to be milder. Calcium supplements and regular exercise will minimise the risk. Again, this is something that will be monitored and will depend on the calcium intake.

None of these problems are life-threatening and Galactosaemic children are otherwise as healthy as any other child provided they continue on their galactose free diet throughout life. In the future we hope that research will lead to better ways of preventing some or all of the long term problems in Galactosaemia.

This information was written with the help of
Dr. Jane Collins, MSc., MD, FRCP, FRCPCH,
Great Ormond Street Hospital
London