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Desperate Measures
We look at the misunderstood genetic disorder, Prader-Willi syndrome
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Imagine that you are hungry all the time, that you are on a diet all the time, and that you can only eat about half as much as everybody else – not to lose weight, but just so you don’t gain weight. This is how American mom Teresa Kellerman describes Prader-Willi syndrome (PWS) on the Prader-Willi Syndrome Arizona Association’s website.
Although considered a rare syndrome by most people, it is one of the most common conditions seen in genetic clinics. But it is also one of the most misunderstood, as it is often not diagnosed. PWS is caused by a missing piece of genetic material on chromosome 15 and it is not more prevalent in a specific gender or race.
Signs of prader-willi syndrome
Dr Engela Honey, a paediatrician at the Department of Genetics, Division of Human Genetics at the University of Pretoria, describes the characteristics of PWS. “It is a genetic condition and presents with severe hypotonia (low muscle tone), increased appetite and obesity from about one year. If the appetite is not controlled, morbid obesity will develop.” Dr Honey explains that different characteristics are apparent at different ages and stages (see “what to look for”).
Five-year-old Luke Legemaate, from Durban, has PWS. His mom, Janet, tells their story. “At birth, the first indication that something was wrong was that Luke was very swollen and floppy,” says Janet. “He was also non-responsive, he never cried and couldn’t feed on his own. We had to tube-feed him.” For two years, Janet and husband Brian had to subject Luke to several tests, one of which was a PWS test that came back negative, but they could not find the answer to what was wrong with their little boy. Although he could walk, with the help of a therapy programme, Luke was “walking, but falling all the time”, says Janet. At the age of two years and eight months, they did another PWS test that came back positive. “We finally had a name (for his condition),” says Janet. “We could now focus on what to do in order for him to reach his full potential.”
Dr Honey explains how PWS is diagnosed. “The diagnosis is made on clinical features and confirmed with blood tests. There are two different tests: FISH (fluorescent in situ hybridisation) where the presence of that specific piece of chromosome 15 is detected or not, and DNA studies where a methylation test detects if that specific area on chromosome 15 is working or not.” The latter is the more accurate of the two tests.
Living with restrictions
“We live in a society that is all about social events and these are generally focused around food,” says Janet. “As a family, this requires significant planning before we venture out. We’ve had to make drastic adjustments about meal times, diets and keeping food away – and these are not just for us. We’ve also had to include extended family and friends. I have, at times, felt like a tyrant because I’ve had to say ‘no!’ yet again to Luke when he wants to eat something outside of his routine or diet. This is something most other children take for granted.” Janet says that taking Luke to the supermarket can also be testing. “He knows he shouldn’t ask for treats. We have to be strict. At times I’ve had to leave the trolley right there in the shop and take him home to make him understand that we cannot relent. Also, on the odd occasion we do visit a restaurant, I have to make it clear to him that he has only one of two choices from the menu. That’s it.” Luke is on a low-calorie diet of 900 calories a day and meal times are strict. Because of the low muscle tone and inactivity, those who suffer from PWS need fewer kilojoules than the normal person. “On a ‘bad’ weekend, Luke can easily pick up 2kg,” says his mom.
Kath Megaw, a clinical dietician from Cape Town, says the amount of calories a person needs depends on their physical structure and age. For an overweight child who is not on growth hormone therapy, a diet of 700 calories per day is recommended. “That breaks down into about 150 calories per meal, three times a day, with 250 calories left over for snacks. It’s not very much, but because of the comparative inability for a person with PWS to exercise (and lose) 700 calories a day, it becomes very necessary to restrict their food intake,” says Megaw.
Management and treatment
PWS is a complex syndrome, where in many cases the characteristics of autism are also present. Parents need to seek professional help to deal with very trying circumstances. There are several professionals whose input is required to help make the life of someone with PWS more bearable (albeit not all of these are a must for each case). There is also no cure for PWS or any best treatment. “Treatment consists of a multidisciplinary team,” says Dr Honey. “This includes a paediatric endocrinologist (to monitor growth hormone therapy), a geneticist, a speech therapist, a dietician, an occupational therapist, a physiotherapist, a psychologist and a remedial teacher.” But Dr Honey says the best “medicine” is early detection and weight management. Megaw reiterates that it is important for food management to be implemented early. “It is far easier to start outright than to remove privileges later because of weight gain. It is also important that you recognise that food-seeking, which may result in morbid obesity, will be a problem and that you take steps to control this before it becomes a life-threatening situation,” says Megaw.
Food management also means locks on pantries, fridges and food cupboards, says Megaw. “Not straight away, but when food-seeking becomes apparent. Although this might seem antiquated and unfair, it is incredibly helpful to the person with PWS to know that food is secure and is not a temptation.”
And the way forward? Janet knows a time will come when they will literally have to lock away food. This is the reality. But for now, they are happy to do whatever it takes to keep their lovable little boy happy and healthy.
What to look for…
During pregnancy
Reduced foetal activity; baby may stay in the breech position
In the neonatal period
Severely hypotonic; struggles to feed; a weak or an absent cry; shows little facial expression; almond-shaped eyes; thin upper lips with down-turned angles of the mouth; sticky and thick saliva; narrow forehead; underdeveloped penis (micropenis) and undescended testicles in boys; in girls, there is hypoplasia (underdevelopment or incomplete development) of the labia minora
In the infant period
Hands and feet are usually small; the ulnar (forearm) borders of the hands and inner side of the legs are usually straight; delayed speech development; hypotonia improves to a point and motor activity increases, but gross motor development is delayed
Childhood period
Between the ages of two and three there is increased appetite and excessive weight gain; excessive sleepiness; decreased pain sensitivity; skin picking; temper tantrums related to food cravings; an increase in body fat mass compared to a low muscle mass, regardless of their weight; linear growth velocity is decreased and they are shorter than their peers; a small number of children may have an autistic personality
Adolescence and adulthood
Sleep and respiratory problems due to inactivity and obesity; behavioural problems, learning difficulties and temper tantrums; usual growth spurt and normal sexual development during adolescence is usually absent due to the lack of normal sex hormone production
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