PRADER-WILLI SYNDROME

WHAT IS PRADER-WILLI SYNDROME?Prader-Willi syndrome is a rare disorder

present at birth that results in a number of physical, mental and behavioral problems. A key feature of Prader-Willi (PRAH-dur VIL-ee) syndrome is a constant sense of hunger that usually begins after the first year of life.

People with Prader-Willi syndrome want to eat constantly and usually have trouble controlling their weight. Many complications of Prader-Willi syndrome are due to obesity.

Common Symptoms Infants

Signs and symptoms of Prader-Willi syndrome generally occur in two stages. Signs of the disorder that may be present in the first year of life include:

Poor muscle tone. A primary sign of Prader-Willi syndrome during infancy is poor muscle tone (hypotonia). Babies may rest with their elbows and knees loosely extended instead of fixed, and they may feel floppy or like "rag dolls" when they're held.

Distinct facial features. Children with Prader-Willi syndrome may be born with almond-shaped eyes, a narrowing of the head at the temples, a turned-down mouth and a thin upper lip.

Failure to thrive. During the first year of life, children with Prader-Willi syndrome may have a poor sucking reflex due to decreased muscle tone. Because poor sucking makes feeding difficult, they tend to gain weight slowly.

Lack of eye coordination (strabismus). The eyes of a child with Prader-Willi syndrome may not move together. Therefore, they may cross or wander to the side.

Generally poor responsiveness. A baby may seem unusually tired, respond poorly to stimulation, wake with difficulty or have a weak cry.

Common Symptoms Cont’d

Early childhoodFrom about ages 1 to 6, other signs of Prader-Willi appear. These problems will remain present throughout life and require careful management or treatment. These signs may include:

Food craving and weight gain. The classic signs of the disorder are a constant craving for food and a rapid gain in weight. Because a child with Prader-Willi syndrome is always hungry, he or she eats frequently and consumes large portions. A child may develop unusual food-seeking behaviors, such as hoarding food or eating things such as garbage or frozen food.

Underdeveloped sex organs. A condition called hypogonadism occurs when sex organs — the testes in men and the ovaries in women — produce little or no sex hormones. This results in underdeveloped sex organs, incomplete development at puberty and in nearly all cases infertility.

Common Symptoms Cont’d Poor growth and physical development. Children with Prader-Willi

syndrome have low muscle mass. They may have short hands and feet. When a person with the disorder reaches full adult stature, he or she is usually shorter than other family members.

Learning disabilities. Mild to moderate mental retardation is a common feature of the disorder. Essentially all people with Prader-Willi syndrome, even those without mental retardation, have learning disabilities.

Delayed motor development. Toddlers with Prader-Willi syndrome often reach milestones in physical movement later than other children. Sitting up by oneself may be delayed until 12 months and walking until 24 months.

Speech problems. Speech is often delayed until a child is 2 years of age. Poor articulation of words may be an ongoing problem.

Behavioral problems. Children may at times be very stubborn or throw temper tantrums, especially when denied food. They may also develop obsessive-compulsive disorder, which results in unwanted, recurring thoughts or repetitive behaviors, or both. Other mental health disorders may develop.

Sleep disorders. Some children with Prader-Willi syndrome may have sleep disorders, including disruptions of the normal sleep cycle and sleep apnea, a condition in which breathing pauses during sleep. Obesity may worsen sleep disorders.

Scoliosis. A number of children with Prader-Willi syndrome develop abnormal curvature of the spine (scoliosis).

Common Symptoms Cont’d Other signs and symptoms of Prader-Willi syndrome may include: Nearsightedness (myopia) Light skin compared with other family members High pain tolerance Skin picking When to see a doctor

A number of conditions can cause some of the early signs of Prader-Willi, such as a failure to thrive, poor muscle tone and poor sucking. Therefore, it's important to get a prompt and accurate diagnosis.

See the doctor if the infant: Has difficulty feeding Doesn't wake easily Doesn't respond to touch Has rag doll-like limbs See a doctor if the older child shows any of the following signs: Rapid weight gain Constant hunger Unusual food-seeking behaviors

Although the exact genes responsible for Prader-Willi syndrome haven't been identified, the problem is known to lie in a particular region of chromosome 15.

With the exceptions of genes related to sex characteristics, all genes come in pairs, one copy inherited from the father (paternal gene) and one copy inherited from the mother (maternal gene). For most types of genes, if one copy is "active," or expressed, then the other copy is also expressed.

However, some types of genes act alone. In other words, it's normal with certain genes for the paternal gene to be expressed and the maternal gene to be "silent." Therefore, if there's an error with the paternal gene, that piece of genetic information is essentially missing.

Causes

Causes Cont’dWhat happens in Prader-Willi syndrome

Prader-Willi syndrome occurs because certain paternal genes that should be expressed aren't for one of the following reasons:

Paternal genes on chromosome 15 are missing.The person has inherited two copies of chromosome 15 from

the mother and no chromosome 15 from the father. There's some error or defect in paternal genes on

chromosome 15.The genetic defect of Prader-Willi syndrome disrupts the

normal functions of a portion of the brain called the hypothalamus. Among its many functions, the hypothalamus controls hunger and thirst and releases hormones that prompt the release of other substances responsible for growth and sexual development. A malfunctioning hypothalamus — caused by the defect on chromosome 15 — interferes with each of these processes, resulting in uncontrollable hunger, stunted growth, sexual underdevelopment and other characteristics of Prader-Willi syndrome.

Risk FactorsDefective or missing portions of paternal genes

responsible for Prader-Willi syndrome usually occur randomly. This means that in most instances, Prader-Willi syndrome can't be prevented. However, in a small number of cases, a genetic mutation inherited from the father may cause Prader-Willi syndrome.

If you have a child with Prader-Willi syndrome and would like to have another baby, consider seeking genetic counseling. A genetic counselor may help determine the risk of having another child with Prader-Willi syndrome.

COMPLICATIONS Obesity-related complications

Many of the possible complications of Prader-Willi syndrome result from obesity. In addition to having constant hunger, people with the disorder have low muscle mass, which requires lower than average calorie needs. This combination of factors makes a person prone to obesity and the medical problems related to obesity. These possible complications include:

Type 2 diabetes. Type 2 diabetes is high blood sugar level due to the body's inability to use insulin efficiently. Insulin plays a vital role in making blood sugar (glucose) — the body's fuel — available to the cells. Obesity significantly increases the risk of diabetes.

Heart disease and stroke. People who are obese are more likely to have high blood pressure, hardened arteries, high cholesterol and other factors that can lead to heart disease and stroke.

Arthritis. Excess weight can cause the bone and cartilage of joints to wear down, resulting in osteoarthritis.

Sleep apnea. This sleep disorder is characterized by pauses in breathing during sleep. The disorder can cause daytime fatigue, high blood pressure and, rarely, sudden death. People with Prader-Willi syndrome may have sleep apnea or other sleep disorders even if they aren't obese, but obesity can worsen sleep problems.

COMPLICATIONS CONTINUED Complications of hypogonadism

Other complications arise from hypogonadism, a condition in which the sex organs don't secrete sufficient amounts of the sex hormones testosterone (males) and estrogen and progesterone (females). These may include:

Sterility. Although there have been a few reports of women with Prader-Willi syndrome becoming pregnant, most people with this disorder are unable to have children (sterile).

Osteoporosis. Osteoporosis is a condition characterized by weak and brittle bones, which can break easily. People with Prader-Willi syndrome are at an increased risk of developing osteoporosis because they have low levels of sex hormones, which help maintain strong bones.

Other complicationsEating large amounts of food quickly, called binge eating, can cause the child's stomach to become abnormally distended (gastric dilatation). Binge eating can also cause choking and any of the other complications associated with obesity.

TESTS AND DIAGNOSISThe presence of other signs, such as

almond-shaped eyes or narrowing of the head at the temples, may also prompt testing. In older children, behavioral problems and weight gain are often the key diagnostic signs of the disorder.

A definitive diagnosis can almost always be made with a laboratory test. Special genetic tests can identify abnormalities in the child's chromosomes that are characteristic of Prader-Willi syndrome.

Treatments and drugsA team of health professionals will likely work with you to

manage the child's condition. Most children with Prader-Willi syndrome will need the following care and treatments:

Good infant nutrition. Many infants with Prader-Willi syndrome have difficulty feeding due to decreased muscle tone. The child's doctor may recommend a high-calorie formula to help the baby gain weight and will monitor the child's development as he or she begins to grow.

Growth hormone treatment. Human growth hormone stimulates growth and influences the body's conversion of food into energy (metabolism). Some studies have suggested that growth hormone treatment in children with Prader-Willi syndrome helps increase growth and decrease body fat, but the long-term effects of growth hormone treatment aren't known. A doctor who treats hormonal disorders (endocrinologist) can help determine whether the child would benefit from growth hormone treatment.

Sex hormone treatment. The endocrinologist may also suggest that the child take hormone replacement therapy (testosterone for males or estrogen and progesterone for females) to replenish low levels of sex hormones. Hormone replacement therapy can help decrease the child's risk of developing thinning of the bones (osteoporosis).

Treatments and Drugs Cont’dHealthy diet. A nutritionist may help you develop a

healthy, reduced-calorie diet to keep the child's weight under control while ensuring proper nutrition.

Overall development. The child will likely benefit from a range of therapies, including physical therapy to improve movement skills and strength; speech therapy to improve verbal skills and articulation; occupational therapy to learn everyday skills; and developmental therapy to learn age-appropriate behaviors, social skills and interpersonal skills. In the United States, early intervention programs providing these types of therapy are usually available for infants and toddlers through a state's health department.

Mental health care. A mental health professional, such as a psychologist or a psychiatrist, may help address any psychological problems the child may have, such as obsessive-compulsive disorder or a mood disorder. Some children may need medication to control behavioral problems.

Treatments and Drugs Cont’dTransition to adult care

Most people with Prader-Willi syndrome will need specialized care and supervision throughout their lives. Many adults with the disorder live in residential care facilities that enable them to eat healthy diets, live safely, work and enjoy leisure activities.

Organizations, such as the Prader-Willi Syndrome Association, can help families find local resources and services.

Also, talk to a doctor for suggestions about making the transition to adult medical care.

Lifestyle and home remedies Tips to help you take care of the child with Prader-Willi

syndrome include the following: Pick up the child carefully. Children with Prader-Willi

syndrome have poor muscle tone, which increases their risk of slipping between the hands when you lift them under their armpits.

Take steps to help prevent binge eating. Adhering to a low-calorie diet is essential to keep the child from becoming overweight. Try to avoid purchasing high-calorie snacks. Store food out of the child's reach. Lock pantries, refrigerators and cupboards. Use small dishes for serving meals.

Supplement the child's diet. If the child is on a restricted-calorie diet, ask the doctor if supplemental vitamins or minerals are necessary to ensure balanced nutrition.

Schedule appropriate screening tests. Be sure to talk to the doctor about having the child screened for complications of Prader-Willi syndrome, including diabetes, osteoporosis and an abnormally curved spine (scoliosis).

Ask the doctor about family support groups in the area. Organizations, such as the Prader-Willi Syndrome Association, provide resources, support groups and educational materials.

Source of Informationhttp://www.mayoclinic.com/health/prader-w

illi-syndrome/DS00922http://www.nichd.nih.gov/health/topics/Prad

er_Willi_Syndrome.cfm