WHAT IS WHS?
We all have genes that are inherited from our parents. Genes are packaged onto chromosomes that are in pairs, each cell in the body has 23 pairs of chromosomes. One chromosome from each pair is inherited from the mother and the other chromosome from each pair is inherited from the father.
A child with Wolf Hirschhorn Syndrome lost a small amount of material from the tip of chromosome 4; the other chromosome 4 is normal. The features of Wolf Hirschhorn Syndrome will occur even if only the very tip of chromosome 4 is missing.
Sometimes it is difficult to see this under a microscope, so more than one blood sample may be taken from the child before the diagnosis is made; in addition, the chromosomes of the parents may have to be examined very carefully. The loss of chromosome 4 may occur in several ways, the main ones are described below: The parents could have entirely normal chromosomes in which case the loss of chromosome 4 material occurred spontaneously, during the production of a particular egg or sperm. In this case, the risks of a similar problem occurring again in a subsequent pregnancy are low.
Alternatively, one or other of the parents have rearranged chromosomes with part of chromosome 4 on another chromosome. This causes the parent no harm since their total genetic material is normal. The parent is said to have a balanced rearrangement. However, there is a risk that children will inherit a chromosome 4 with a piece missing, such children will be affected and said to have an unbalanced rearrangement.
Tests can be done early in a subsequent pregnancy to detect any abnormal chromosomes in the baby: the advantages and disadvantages of these tests should be discussed with a Doctor or Genetic Counsellor. The diagnosis of Wolf Hirschhorn Syndrome is made when blood has been taken from a newborn baby to try to discover why he or she has a number of unusual physical features. If a baby is found to be lighter than expected or to have a shape of face very different from the parents, a close examination may show a number of other variations. There may be unusually shaped ears, hands or genitalia and there may be evidence of defects in the heart or palate. The name Syndrome is used when there are a cluster of these abnormalities. Before it was possible to examine the chromosomes, a number of syndromes were described and then the proof depended on whether there were a reasonable number of the described features in any individual. Since the 1960’s it has been possible to count the chromosomes and later developments have allowed individual chromosomes to be examined very carefully. In Wolf Hirschhorn Syndrome there is a small piece of the short arm of chromosome 4 missing.
It is very difficult to understand this unless we know more about chromosomes. Let’s start from the beginning. We are made up of millions and millions of tiny cells. These bricks which build up our body can only be seen under a microscope. Different parts of the body have different types of cells, but even if the cell is a tireless heart muscle cell or an inspired brain cell, the centre of the cell is very similar. This centre is called the nucleus. The nucleus is made up of an amazingly neat chemical called desoxyribose nucleic acid (DNA).This DNA is a long spiral shaped molecule which contains all our genes. Genes are the bits of information which tell our developing bodies exactly what shape to be. Put scientifically, the genes which are coded in the DNA sequence control the types of chemicals which build up the shape and size of every part of the body. Try to imagine that the DNA in every nucleus is like a tape bound inside a cassette. The words on the tape could be commands which tell people what to do. If the instructions coming from the tape were telling someone how to construct a car or computer, just imagine what would happen if a piece of the tape was damaged or missing. This is roughly what happens in conditions like Wolf Hirschhorn Syndrome. Here some of the DNA is missing. So what are chromosomes?
When cells divide the DNA gathers up into convenient rolls like skeins of wool. The tangles of DNA are called chromosomes and they are of different lengths. They gather in 23 pairs and are numbered 1 to 22 with 1 being the largest. The 23rd pair are the sex chromosomes and are called XX (girls) and XY (boys). Wolf Hirschhorn Syndrome affects chromosome 4. This is a large chromosome but it is only the short arm which is affected (chromosomes have a lump near the middle and the pieces either side are called arms, since the lump is not exactly in the centre there is a short arm and a long arm either side of it).
Occasionally this missing piece of chromosome is stuck onto another chromosome (this is called translocation). A few parents have a balanced translocation meaning that they have the correct amount of DNA and therefore haven’t lost any genes. However, when the cells divide up their chromosomes to form their eggs or sperms the resulting offspring may have that short chromosome and not have the piece which is stuck onto the other chromosome.
Most parents have normal chromosomes and the chances of having another baby with the same condition is rare, but
if a parent has a balanced translocation of the short arm of Chromosome 4 then there is a much higher chance of
another baby being affected. Your genetic counsellor will give you more information about this. Some parents feel
very upset when they find that it was their chromosome that led to this condition. It is most unfair to blame themselves
for this since we have no idea ourselves about how our chromosomes are arranged. There is no way in which we can
change this nor was there any way in which we could have caused it to happen.
This might be a good point to look at a philosophical point. When the difficult news is broken to parents that their little
baby has such a major problem which will severely affect his or her future, a number of parents feel a great bitterness
about the whole design of the universe as well as the sadness and bereavement for the baby they were expecting to
have. They feel that it is totally unfair that chromosomes should be so weak that they can break or get damaged in this
way. They may feel that the whole of life has ganged up against them to produce such bad luck. This is very difficult
and can distance them from supportive family or friends especially if linked to religious groups. It seems that we could
not have developed into such complicated but remarkable beings if it hadn’t been for occasional breaks in the
chromosomes way back at the dawn of life. Spontaneous changes in the chromosomes which led to alterations in the
shape or activity of life forms were probably the way we developed from the original one cell creatures. Perhaps it is
at least some consolation that the problem is caused by the very activity which allowed us to evolve to what we are
Every child with Wolf Hirschhorn Syndrome is different but they share a number of characteristics. It will be most
helpful to consider these in the order of importance to the child at various ages.
This list is rather daunting but it may help in making sure that your child has had all these areas checked. The severe
learning difficulties and the muscle weakness are the most difficult problems. There is no medical treatment which can
improve these and it is these which are going to restrict his or her opportunities. It is also these which increase the
risk of chest infections and ultimately reduce the life expectancy.