About willi-prader syndrome
What is willi-prader syndrome?
Prader-Willi syndrome (PWS) is a genetic multisystem disorder characterized during infancy by lethargy, diminished muscle tone (hypotonia), feeding difficulties, and poor weight gain. In childhood, features of this disorder include short stature, small genitals and an excessive appetite because affected individuals do not feel satisfied after completing a mean (satiety). Without intervention, this can lead to overeating and the gradual onset of obesity. The food compulsion requires constant supervision. Individuals with severe obesity may have an increased risk of cardiac insufficiency, sleep apnea, diabetes, and other serious conditions that can cause life-threatening complications. All individuals with PWS have some cognitive impairment that ranges from low normal intelligence with learning disabilities to mild to moderate intellectual disability. Behavioral problems are common and can include temper tantrums, obsessive/compulsive behavior, and skin picking. Motor milestones and language development are often delayed. PWS occurs due to abnormalities affecting certain genes in a specific region of chromosome 15. These abnormalities usually result from random (sporadic) errors in development, but are sometimes inherited.
Originally described in the medical literature in 1956, PWS is the first disorder confirmed to be due to imprinting errors (see Causes section). It is the most common genetic cause of life-threatening childhood obesity. The disorder was once known as hypogonadism, hypotonia, hypomentia, obesity (HHHO).
What are the symptoms for willi-prader syndrome?
Signs and symptoms that may be present from birth include:
- Poor muscle tone. A primary sign 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 may be born with almond-shaped eyes, a narrowing of the head at the temples, a turned-down mouth and a thin upper lip.
- Poor sucking reflex. Infants may have a poor sucking reflex due to decreased muscle tone. Poor sucking makes feeding difficult and can result in failure to thrive.
- Generally poor responsiveness. A baby may seem unusually tired, respond poorly to stimulation, have a hard time waking up or have a weak cry.
- Underdeveloped genitals. Males may have a small penis and scrotum. The testicles may be small or not descended from the abdomen into the scrotum (cryptorchidism). In females, the clitoris and labia may be small.
Early childhood to adulthood
Other features of Prader-Willi syndrome appear during early childhood and remain throughout life, requiring careful management. These features may include:
- Food craving and weight gain. A classic sign of Prader-Willi syndrome is a constant craving for food, resulting in rapid weight gain, starting around age 2 years. Constant hunger leads to eating often and consuming large portions. Unusual food-seeking behaviors, such as hoarding food, or eating frozen food or even garbage, may develop.
- Underdeveloped sex organs. A condition called hypogonadism occurs when sex organs (testes in men and ovaries in women) produce little or no sex hormones. This results in underdeveloped sex organs, incomplete or delayed puberty, and in nearly all cases, infertility. Without treatment, women may not start menstruating until their 30s or may never menstruate, and men may not have much facial hair and their voices may never fully deepen.
- Poor growth and physical development. Underproduction of growth hormone can result in short adult height, low muscle mass and high body fat. Other endocrine problems may include underproduction of thyroid hormone (hypothyroidism) or central adrenal insufficiency, which prevents the body from responding appropriately during stress or infections.
- Cognitive impairment. Mild to moderate intellectual disability, such as issues with thinking, reasoning and problem-solving, is a common feature of the disorder. Even those without significant Intellectual disability have some learning disabilities.
- Delayed motor development. Toddlers with Prader-Willi syndrome often reach milestones in physical movement — for example, sitting up or walking — later than other children do.
- Speech problems. Speech is often delayed. Poor articulation of words may be an ongoing problem into adulthood.
- Behavioral problems. Children and adults may at times be stubborn, angry, controlling or manipulative. They may throw temper tantrums, especially when denied food, and may not tolerate changes in routine. They may also develop obsessive-compulsive or repetitive behaviors, or both. Other mental health disorders, such as Anxiety and skin picking, may develop.
- Sleep disorders. Children and adults with Prader-Willi syndrome may have sleep disorders, including disruptions of the normal sleep cycle and a condition in which breathing pauses during sleep (sleep apnea). These disorders can result in excessive daytime sleepiness and worsen behavior problems.
- Other signs and symptoms. These may include small hands and feet, curvature of the spine (scoliosis), hip problems, reduced saliva flow, nearsightedness and other vision problems, problems regulating body temperature, a high Pain tolerance, or a lack of pigment (hypopigmentation) causing hair, eyes and skin to be pale.
What are the causes for willi-prader syndrome?
Prader-Willi syndrome is a genetic disorder, a condition caused by an error in one or more genes. Although the exact mechanisms responsible for Prader-Willi syndrome haven't been identified, the problem lies in the genes located in a particular region of chromosome 15.
With the exception of genes related to sex characteristics, all genes come in pairs — one copy inherited from your father (paternal gene) and one copy inherited from your mother (maternal gene). For most types of genes, if one copy is "active," or expressed, then the other copy also is expressed, although it's normal for some types of genes to act alone.
Prader-Willi syndrome occurs because certain paternal genes that should be expressed are not for one of these reasons:
- Paternal genes on chromosome 15 are missing.
- The child 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.
In Prader-Willi syndrome, a defect on chromosome 15 disrupts the normal functions of a portion of the brain called the hypothalamus, which controls the release of hormones. A hypothalamus that isn't functioning properly can interfere with processes that result in problems with hunger, growth, sexual development, body temperature, mood and sleep.
In most cases, Prader-Willi syndrome is caused by a random genetic error and is not inherited. Determining which genetic defect caused Prader-Willi syndrome can be helpful in genetic counseling.
What are the treatments for willi-prader syndrome?
Early diagnosis and treatment can improve the quality of life for people with Prader-Willi syndrome. A team of health professionals will likely work with you to manage the condition.
Your team may include a doctor who treats hormonal disorders (endocrinologist), behavior specialists, a dietitian, physical and occupational therapists, a mental health professional, a geneticist, and other specialists as needed.
Although specific treatments vary depending on symptoms, most children with Prader-Willi syndrome will need the following:
- Good nutrition for infants. Many infants with Prader-Willi syndrome have difficulty feeding due to decreased muscle tone. Your child's pediatrician may recommend a high-calorie formula or special feeding methods to help your baby gain weight and will monitor your child's growth.
- Human growth hormone (HGH) treatment. HGH treatment in children with Prader-Willi syndrome helps increase growth, improves muscle tone and decreases body fat. A doctor who treats hormonal disorders (endocrinologist) can help determine whether your child would benefit from HGH and discuss any risks. A sleep study is usually recommended before starting growth hormone treatment.
- Sex hormone treatment. Your endocrinologist may suggest that your child take hormone replacement therapy (testosterone for males or estrogen and progesterone for females) to replenish low levels of sex hormones. Hormone replacement therapy usually starts when your child reaches the normal age for puberty and can help reduce the risk of developing thinning of the bones (osteoporosis). Surgery may be needed to correct undescended testicles.
- Weight management. A dietitian can help you develop a healthy, reduced-calorie diet to help manage your child's weight while ensuring proper nutrition. A restricted-calorie diet may require supplemental vitamins or minerals to ensure balanced nutrition. Increasing physical activity and exercise can help manage weight and improve physical functioning.
- Treatment of sleep disturbances. Treating sleep apnea and other sleep problems can improve daytime sleepiness and behavioral issues.
- Various therapies. Your 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 occupational therapy to learn everyday skills. Developmental therapy to learn age-appropriate behaviors, social skills and interpersonal skills also may help. In the U.S., early intervention programs with these types of therapy are usually available for infants and toddlers through a state's health department. During school years, educational planning and support can maximize learning.
- Behavior management. Setting strict limits on behavior, schedules and access to food and strict supervision of food intake may be required. Some people may need medication to manage behavior problems.
- Mental health care. A mental health professional, such as a psychologist or a psychiatrist, may help address psychological problems — for example, obsessive-compulsive behaviors, skin picking or a mood disorder.
- Other treatments. These may include addressing specific symptoms or complications identified by eye exams for vision problems, tests for hypothyroidism or diabetes, and examinations for scoliosis.
Transition 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.
As your child approaches adulthood, consider these strategies:
- Find local resources and services for adults through your child's school and organizations such as the Prader-Willi Syndrome Association.
- Investigate guardianship issues, wills and special needs trusts that address future care and supervision for your child.
- Talk to your child's doctor for suggestions about making the transition to adult medical care.
What are the risk factors for willi-prader syndrome?
In most people with PWS (about 60%), the PWS/AS region of the father’s chromosome 15 is missing or deleted. This chromosomal deletion results from a random error in development and is not inherited (or de novo deletion). Thus, most cases of PWS occur sporadically and the risk of recurrence in another pregnancy is less than 1%.