Edwards' syndrome (trisomy 18)

Edwards' syndrome is a rare genetic condition in which the cells carry an extra, third copy of chromosome 18. That spare chromosome throws out the fine tuning of early development: the heart, the kidneys, the brain, the face, the hands and the feet are all affected. Most often it is picked up during pregnancy, less often in the first days after birth. It cannot be cured, because medicine has no way of altering a set of chromosomes, and an honest conversation about it usually opens with very hard words. But there is an enormous distance between "incurable" and "nothing can be done", and almost everything worth saying from here on fits into exactly that space.

Where the extra chromosome comes from

In every cell, chromosomes come in pairs: one from the mother, one from the father. As eggs and sperm mature the pairs separate, and occasionally pair number 18 does not separate at all, so three copies rather than two end up in the embryo. It is a random error of cell division, at a moment nobody can influence.

Which brings up the thing parents most need to hear first: there is no cause to go looking for. No medicine taken, no cold caught, no glass of wine drunk before the pregnancy was known about, no job and no amount of stress has anything to do with trisomy 18. The one established factor is the mother's age: the older she is, the likelier it becomes that chromosomes fail to separate, and that holds for any trisomy. Even so it can happen at any age, and most of these pregnancies occur in younger women simply because younger women have more babies.

Recurrence is very unusual: after one such pregnancy the risk in the next is a little above average but still very small. There is a rarer situation again, in which the extra chromosome 18 material reaches the baby because of a rearrangement of chromosomes in one of the parents; the chance of it happening again is then different and is worked out individually. That is why families are offered genetic counselling and a karyotype test — not to find someone to blame, but to know what to expect next time.

Three forms, and why they are not the same

The outlook in trisomy 18 varies enormously, and it depends above all on how many cells ended up with the extra chromosome.

• Full trisomy 18. The extra chromosome is in every cell. This is the commonest and the most severe form, and it accounts for the great majority of cases.
• Mosaic trisomy 18. The error happened after conception, as the embryo was dividing, so some cells carry the extra chromosome and others have the usual set. The larger the proportion of normal cells, the milder the picture, and no test can predict that in advance.
• Partial trisomy 18. What is duplicated is not a whole chromosome but a piece of one. This is very rare, and how severe it is depends on which section has been copied.

Tests in pregnancy establish that there is a trisomy, but they almost never answer the question of how this particular child will develop. The form is pinned down after birth, and it shapes both the follow-up and the conversation about the future.

How it looks in a newborn

Every baby with Edwards' syndrome has its own set of features, and no one baby has the whole list. But some recur often enough for the diagnosis to be suspected in the delivery room.

• a very low birth weight despite a full-term pregnancy;
• a small head with a prominent back to it, a small lower jaw, low-set ears;
• hands held in fists with the index finger and little finger crossing over their neighbours — one of the most recognisable signs;
• feet with a rounded sole, giving a rocker-bottom shape, or club foot;
• cleft lip and cleft palate;
• heart defects, present in nearly every baby and largely deciding how the first weeks go;
• kidney abnormalities, defects of the abdominal wall, differences in the spine;
• weak sucking, difficulty feeding, bringing up milk;
• pauses in breathing and an unsteady breathing pattern from the first hours;
• very low muscle tone or, conversely, increased tone.

Severe developmental disability is present in every child with this syndrome, and its extent only becomes clear over time.

What the tests in pregnancy show

Antenatal programmes are organised differently from country to country, so your own doctor will give you the exact timings and the exact tests. The underlying principle is the same everywhere and has two steps that are worth keeping apart.

Screening answers the question of how likely something is, not whether it is there. At the end of the first trimester a combined test is done: a scan measuring the fluid at the back of the baby's neck, plus a blood test from the mother. If that window has been missed, a blood test on a different pattern is offered in the second trimester. There is also non-invasive prenatal testing, which detects fragments of the baby's DNA in the mother's blood: it is more accurate than the other screens but is still a screen, and its result is not a diagnosis.

Diagnostic testing does give a definite answer, because it examines the baby's own cells: a sample is taken either of chorionic villi or of amniotic fluid. Both are done under ultrasound guidance, both carry a small risk of losing the pregnancy, and that is always explained beforehand. A further source of information is the detailed scan in the second trimester, which shows heart defects, the posture of the hands and feet, and poor growth.

None of these tests is compulsory, and you can decline at any stage. That is not a formality: some parents want to know everything in advance so they can prepare and choose where to give birth, and others deliberately would rather not know — both decisions are reasonable. The only thing worth settling in advance with your doctor or midwife is what you would do with the answer, because that is the real question.

The conversation about outlook

Plain speaking is needed here, because softened phrasing at this point simply costs time.

Most pregnancies with full trisomy 18 end in miscarriage or stillbirth. Of the babies born alive, a substantial number do not get through the first days and weeks, usually because of heart defects and pauses in breathing; a minority reach their first birthday, and in the full form adulthood is reached by a very small number. With the mosaic and partial forms the picture is different: the effects can be considerably milder, some of these children grow up and go to school with support, and some become adults and work.

All of that is statistics, not a timetable for one particular child: the numbers give a frame but do not say what this child will be like or how long he or she will live. Children with Edwards' syndrome know their parents, respond to a voice and to touch, have things they like and things they do not, and remain themselves — with their own character and their own habits — exactly as any other child does.

What can be done

No treatment exists that could take the extra chromosome away. But care here is not an empty word: it is aimed at keeping the child free of pain and fear and as well as possible, and at making sure the family is not left alone with it. Several professionals look after the baby at once — a neonatologist, a cardiologist, a neurologist, a surgeon, a feeding specialist, a physiotherapist — and together with the parents they draw up a care plan and revise it as it becomes clearer what helps.

• Heart and breathing. Regular monitoring, breathing support, treatment of heart failure. Whether to operate on the heart is decided case by case: for some it clearly improves life, for others it brings more burden than benefit, and parents take part in that decision on equal terms with the doctors.
• Feeding. Weak sucking is one of the main problems of the early weeks. Specific feeding techniques help, as do thickeners and, where needed, a tube or a gastrostomy, so that the baby gets enough without being exhausted by the act of feeding itself.
• Development and comfort. Physiotherapy and work on positioning, help with speech and communication, pain relief, treatment of seizures, management of constipation and reflux: everything that decides the quality of each individual day.
• Palliative care. It is often taken to mean giving up on treatment, and that is wrong. The palliative team comes in alongside active care, eases pain and breathlessness, supports the parents and gives them a break. Involving them early is not surrender.

Immediate help is needed for pauses in breathing, a blue colour, floppiness with refusal to feed, and seizures: those are not waited on — call an ambulance (across Europe the single number is 112). Parents of a child with this diagnosis are usually told in advance what to do in these situations and where to turn first.

And a word about the parents themselves. This is grief that begins before the loss and sometimes lives alongside a family for years, and carrying it alone is not possible. Psychological support, groups of families with the same diagnosis, and the chance to talk to someone who has already been through it help every bit as much as the medical side.

Online consultation

A remote appointment is most often needed at two points. The first is when a screening result is in hand and its meaning is unclear: the doctor will explain the difference between a probability and a diagnosis, what tests come next, how chorionic villus sampling differs from amniocentesis and what each one risks, so that the decision is taken calmly rather than in a panic. The second is when the diagnosis is already known: then it is worth going through which specialists to involve, how to organise feeding and follow-up, what to ask at face-to-face appointments, and how to reach palliative and psychological support. Planning a future pregnancy is another thing that is convenient to talk through online. The diagnosis itself is only ever made in person, from the baby's own cells, and no conversation over a screen can take its place.

This material is for information only and does not replace medical advice.