I watched a programme the other night on TV called 'Can't stop eating' and before you think, oh not another programme about obesity, this was different. It concerns a syndrome called Prado Willi syndrome.

Prader-Willi Syndrome (PWS) was first described in 1956 by Swiss doctors, Prof. A Prader, Dr A Labhart and Dr H Willi, who recognised the condition as having unique and clearly definable features. These features are:-
Hypotonia: weak muscle tone, and floppiness at birth.
Immature development of sexual organs and other sexual characteristics.
Obesity caused by excessive appetite and overeating and a decreased calorific requirement owing to low energy expenditure levels. Central nervous system and endocrine gland dysfunction: causing varying degrees of learning disability, short stature, hyperphagia, somnolence, and poor emotional and social development.
Many people with PWS also exhibit characteristic facial and other physical
features. These include: almond-shaped eyes, a narrow forehead (measured across), a down-turned mouth with a triangular-shaped upper lip, and small hands and feet.
People with PWS have poor large muscle strength, often coupled with poor coordination and balance. Muscle tone can be improved with appropriate therapy and exercise. Small muscle strength is usually better.

Think you made a bit of a typo in the title Peggy, it is of course Prader-Willi! I knew a family who had a son with this condition and like many people with PWS he did have borderline or moderate learning difficulties. Some
people have recorded IQs of 90 or above, but a minority have severe learning difficulties. The average IQ is around 70 or slightly lower, although individuals may sometimes find it difficult to perform at their IQ level, as emotional and social skills are often less developed. Reading and writing skills are usually considerably better than number skills and abstract thinking. Individuals often excel at sedentary activities such as jigsaw puzzles, "word searches", sewing, drawing and colouring and he certainly did that, he could do a jigsaw in half the time I could!

PWS is caused by an abnormality on chromosome 15 which occurs around the time of conception. The majority of cases (about 70%) are caused by a deletion on the chromosome 15 inherited from the father, whilst about 25% are caused by inheriting two chromosome 15s from the mother, instead of one from the mother and one from the father (maternal disomy). A small minority of people have a translocation or imprinting irregularity involving chromosome 15. The recurrence risk of PWS in a family is very small. No blame is attributable to either parent. Thinking at present is that PWS is a purely accidental occurrence.

A few people have a PWS diagnosis, but do not have the typical physical features. For example they may be much taller than usual, even without a growth hormone.
PWS-like symptoms can be "acquired" by damage to the hypothalamus during a person's life or from a dysfunction of the hypothalamus. This may be as a result of a head injury, or from a tumour, or from surgery following the removal of a tumour, or from a dysfunction from birth. In these cases, the person does not have any of the genetic abnormalities and few of the physical characteristics of PWS, but acquires some or all of the behavioural and appetite problems which are associated with the syndrome. Management techniques used with people with true PWS can also be helpful in acquired PWS.

A study carried out in one health region in the UK in 2000 estimated birth incidence to be in the region of 1:22,000, Previous estimates have estimated a birth incidence between 1:10,000 and 1:25,000. Much of the uncertainty with regard to the statistics for incidence and prevalence is due to the fact that PWS may still be undiagnosed in some people.

Babies born with PWS are very floppy at birth, and the ability to suckle is weak or absent. Tube-feeding might therefore be required for the first few days or weeks of life because breast-feeding is rarely initially successful. Babies show little interest in feeding during the first few months of their lives and have a very weak cry, and sleep for most of the time during the early weeks. Male babies may have noticeably underdeveloped genital organs. Female babies may also have underdeveloped genitalia, but this is much harder to detect. Developmental milestones such as sitting, standing, walking and talking are generally delayed, but most children with PWS are able to attain all these by the time they are about 5 years old. Infants with PWS are very lovable and placid, and it is true that they seem to draw admiration wherever they go.

The real tell tale marker of this condition begins some time between the ages of one and four years, when children with PWS begin to show a heightened interest in food and in severe cases develop what appears to be an insatiable appetite, so that they will try to obtain food by any means possible.

The degree to which this occurs varies considerably between individuals, but there is always a preoccupation with food in play and talk. This can be helped by good management, dietary control and educating the child about his or her diet. However, if energy intake has not been carefully monitored, weight gain is rapid; hence, a lower calorie diet (energy controlled regime) is essential throughout the person's life. An appropriate exercise programme helps to keep weight levels down and also improves muscle strength. If weight is not controlled, fat accumulates in a characteristic way on the buttocks, stomach, lower trunk and thighs. Children with PWS are generally placid and friendly, but may begin to exhibit stubborn or obsessive behaviour, and outbursts of temper if they cannot get their own way or are denied access to food. The weight gain that dogs people with this condition starts at this stage and it is vitally important to nip this in the bud for the child's sake.