Angelman syndrome

A child who laughs a great deal and easily, is drawn to water, barely speaks and is late to walk: out of these seemingly unrelated traits comes the recognisable picture of Angelman syndrome. It is a rare condition present from birth, in which a gene that nerve cells need in order to develop stops working in one small region of a chromosome. It does not get worse over time and does not take away skills already gained, but it stays for life and calls for constant help from adults. Life expectancy is close to usual.

The first thing parents notice

In the first months a baby usually gives no cause for concern. Questions start in the second half of the first year: no sitting without support, no babbling, no attempts to repeat syllables, an awkward reach for a toy. Sometimes feeding draws attention even earlier, because the baby cannot coordinate sucking with swallowing, brings milk back up often and gains weight slowly. In that case tube feeding is used for a while and reflux of stomach contents into the gullet is treated.

Around the age of two it becomes noticeable that the head is growing more slowly than in other children and is flattened at the back. Doctors confirm this by measuring, not by eye.

The behaviour that gives it away

The set of traits is fairly consistent, though no single child has all of them.

• Frequent laughter and smiling with no outward reason, easy excitement, hand flapping and clapping.
• Constant movement and a very short attention span: holding the child on one activity for more than a couple of minutes is hard work.
• Little sleep. Many wake in the night and stay awake for long stretches, and for the family this is often the hardest part.
• A particular pull towards water, towards the rustle of plastic, towards shiny objects.

The child is usually warm and interested in people. That is an important difference from conditions in which contact with others is difficult.

Movement, speech and ways of getting through

Walking comes later than usual and stays unsteady: a wide stance, arms often held up, balance that lets the child down. The hands may tremble and the legs feel stiff. Over the years joints tend to become permanently tight and the spine tends to curve sideways, so the back and the walking pattern are reviewed regularly.

Speech barely develops: most children end up with a handful of words or none. Understanding, though, reaches much further than the ability to speak, and this is where gestures, picture cards, recorded-voice buttons and communication apps on a tablet earn their place. The sooner a child has one reliable way of saying "I want", "it hurts" or "enough", the calmer everything else becomes.

Seizures: when they start and what to do

Seizures affect most children, usually first appearing between the ages of one and three, and they take different shapes, from a still stare into nowhere to whole-body stiffening with jerks. An electroencephalogram is used to clarify the picture; in this syndrome the tracing is fairly characteristic and helps make the diagnosis. Seizures are kept in check with anti-seizure medicines, which the neurologist has to tailor case by case, and that tailoring takes time. By school age they usually become less frequent, though they can return in adulthood.

Call the emergency services if a seizure lasts longer than five minutes, if seizures follow one another without the child regaining consciousness in between, if the child does not come round afterwards, if the lips turn blue or breathing becomes broken, and also if this is the first seizure the child has ever had. A separate urgent reason is choking followed by coughing and fever: food may have gone into the airway.

What is happening in the genes

It comes down to the UBE3A gene on chromosome 15. There are two copies of it, one from the mother and one from the father, but in brain cells only the maternal copy works; the paternal one is switched off from birth. The syndrome arises when the maternal copy is lost or broken, because nothing can stand in for it.

Several routes lead there. Most often the piece of the maternal chromosome carrying the gene is missing. Less often the child receives both copies of chromosome 15 from the father, which means two switched-off copies. There can also be a fault inside the gene itself, or in the mechanism that decides which copy is active. Almost always this is an accident that happened at conception: the parents are healthy and did nothing to cause it. The chance of it happening again in the same family, however, depends on which mechanism was involved and varies considerably, so it is worth identifying rather than stopping at the diagnosis alone.

How the diagnosis is confirmed

Suspicion is raised by the combination of developmental delay, unsteady walking, absent speech and that characteristic behaviour. Confirmation comes from a blood test. First it is checked whether the relevant region of chromosome 15 is working, and this test picks up most cases. Then the cause is pinned down: a missing piece of chromosome, both chromosomes from the father, or a change inside the gene itself. If none of these is confirmed, other conditions with a similar appearance are looked for.

The diagnosis is most often made between the age of one and six. With the result in hand it is worth seeing a genetics specialist, who can explain what the finding means for this child and for future pregnancies.

What helps day to day

There is as yet no medicine that removes the cause, and it should not be promised. Steady work by a small team, on the other hand, achieves a great deal. Physiotherapy improves balance and walking and stops joint stiffness from setting in. A speech and language therapist chooses and fine-tunes the system the child will use to communicate. Behavioural strategies and a predictable routine lower agitation and make sleep easier; sometimes the doctor adds something to help with falling asleep. Squint, the back, the teeth and nutrition are each watched separately.

Things ease with age: restlessness and excitability subside, sleep settles, and skills keep being added little by little. Limited speech and the need for support remain, but general health is usually good.

Online consultation: what a doctor can do

A video appointment is well suited to everything that does not need the doctor's hands. Going through the genetics report and understanding what exactly was found and what it means for other children in the family. Agreeing how to keep a seizure diary and what to record so the neurologist has something to work with. Checking that anti-seizure medicines are being taken correctly and talking through side effects. Building a plan for sleep and for the shape of the day. Pointing out which specialists are needed first and where a family living under constant strain can find support. A seizure happening right now, a choking episode or a head injury are not matters for a remote appointment but for emergency care.

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