Symptoma

Prader-Willi Syndrome

Prader Willi Syndrome

Prader–Willi syndrome is a rare, genetic disorder characterized especially by failure to thrive, short stature, mental retardation, hypotonia, functionally deficient gonads, and obesity.

The presentation of Prader-Willi syndrome depends upon the age of the patient.

In fetal life:

In neonates and children:

In adults:

  • Short Stature

    Clinical manifestations include mental retardation; muscular hypotonia; hyperphagia; obesity; short stature; hypogonadism; strabismus; and hypersomnolence. [icd9data.com]

    stature (adult), small hands and feet, mild dysmorphology, and behavior problems which can be severe. [curlie.org]

    Prader-Willi syndrome is a genomic imprinting disorder, characterized by obesity, hyperphagia, mental retardation, short stature and hypogonadism. The presenting signs and symptoms depend upon the age at which the patient is seen. [ncbi.nlm.nih.gov]

    Prader–Willi syndrome is a rare, genetic disorder characterized especially by failure to thrive, short stature, mental retardation, hypotonia, functionally deficient gonads, and obesity. [symptoma.com]

  • Weight Gain

    Newborns are often small and floppy Male infants may have undescended testicles Other symptoms may include: Trouble feeding as an infant, with poor weight gain Almond-shaped eyes Delayed motor development Narrowed head at the temples Rapid weight gain [nlm.nih.gov]

    Regardless of the underlying mechanism for lower TEE, the estimation of energy requirements with the use of equations derived for the general population would result in weight gain in individuals with PWS. [ncbi.nlm.nih.gov]

  • Weakness

    RESULTS: Fourteen boys and six girls presented with hypotonia, poor responsiveness, feeding difficulty, and infrequent, weak crying. [ncbi.nlm.nih.gov]

    Babies born with PWS have poor muscle tone and a weak cry. They initially are slow feeders and appear undernourished. The feeding problems improve after infancy. [stanfordchildrens.org]

    Babies : High-calorie formula may help an infant stay at a healthy weight if he can't eat well because of weak muscle tone. [webmd.com]

    […] fetal life: Reduced fetal movements and abnormal position Polyhydramnios Requirement for caesarean section In neonates and children: Feeding difficulties (poor suckling reflex) Delayed developmental motor milestones Delayed onset of speech Thick saliva Weak [symptoma.com]

  • Feeding Difficulties

    Conclusion: Neonatal hypotonia, reduced FM, feeding difficulties and cryptorchidism should immediately suggest PWS, yet late diagnosis continues in some cases. [ncbi.nlm.nih.gov]

  • Infertility

    Until recently, experts believed that people with PWS were infertile. [nichd.nih.gov]

    The use of assisted reproductive technologies (ART) has increased gradually in the treatment of infertility worldwide. [ncbi.nlm.nih.gov]

    Puberty is delayed in patients of Prader-Willi syndrome and infertility is common. Testing should be done to check for gene abnormalities before birth so that appropriate measures can be taken beforehand. [symptoma.com]

    Prader–Willi syndrome genetic disorder on chromosome 15, causing weak muscles, slow development, obesity, intellectual impairment, narrow forehead, small hands/feet, short height, light skin/hair, and infertility Upload media Wikipedia Instance of disease [commons.wikimedia.org]

  • Overeating

    Prader-Willi syndrome (PWS) is characterized by extreme floppiness at birth, impaired sexual development, short stature, severe over-eating, characteristic physical features and learning disabilities (LD). [ncbi.nlm.nih.gov]

    Access of child to food should be restricted to prevent bouts of overeating and to keep their weight in check. Muscle activity like sports should be encouraged to overcome hypotonia and motor problems. [symptoma.com]

    The two main genetic causes and other rarer cause of PWS all involving chromosome 15 give rise to a pattern of atypical early development characterised by extreme floppiness and failure to thrive at birth with the subsequent emergence of severe over-eating [ipwso.org]

  • Failure to Thrive

    Prader-Willi syndrome (PWS) is characterized by infantile lethargy and hypotonia causing poor feeding and failure to thrive, childhood obesity, short stature, and hypogonadism. [ncbi.nlm.nih.gov]

    The two main genetic causes and other rarer cause of PWS all involving chromosome 15 give rise to a pattern of atypical early development characterised by extreme floppiness and failure to thrive at birth with the subsequent emergence of severe over-eating [ipwso.org]

  • Insatiable Hunger

    This is presumed to be the basis of the insatiable hunger and obesity of patients with the syndrome. [onlinelibrary.wiley.com]

    Along with insatiable hunger, symptoms of the condition include: mild to moderate intellectual impairment and learning disabilities, behavioral problems, sleep abnormalities, and usually infertility. [medicaldaily.com]

    Published January 25. 2020 1:02PM Updated January 26. 2020 12:55AM By Tim Cook Cami Grundy, 21, of Groton lives with a rare disorder called Prader-Willi Syndrome, a condition that along with learning disabilities creates an insatiable hunger in the individual [theday.com]

    This compelling one-hour documentary follows four families – each with children living with Prader-Willi Syndrome (PWS) - also known as insatiable hunger. Click here to subscribe to the channel: Follow us on Facebook - ... [youtube.com]

    The affected persons often have an insatiable hunger, overeate and steal food. It is a relatively common congenital disorder with an incidence of about 1 in 10.000 live births. [whonamedit.com]

  • Increased Appetite

    Increased appetite usually starts during childhood and can be gradual. [youtube.com]

    Increased appetite Children with Prader-Willi syndrome develop an increased appetite and eat an excessive amount of food if they have the opportunity. The medical name for this is hyperphagia. [nhs.uk]

    During this phase, the children do not have an increased appetite or increased interest in food. [pwsausa.org]

    It is caused by increased appetite, decreased perception of satiety and obsessive and compulsive behaviour towards food. Ghrelin is a powerful appetite-stimulating hormone. [clinicaltrials.gov]

  • Malocclusion

    The patient was diagnosed with an Angle Class II malocclusion and a skeletal Class II jaw-base relationship with a deep overbite. [ncbi.nlm.nih.gov]

  • Almond-Shaped Eyes

    The clinical appearance of PWS includes dysmorphic facial features with almond-shaped eyes, a narrow bifrontal diameter, and a thin upper lip; short stature; central obesity; and small hands and feet. [ncbi.nlm.nih.gov]

    Characteristic facial features (a narrow forehead, almond-shaped eyes, a thin upper lip and down-turned mouth), as well as very small hands and feet, are frequently observed. [orpha.net]

    (menkes, textbook of child neurology, 5th ed, p229) Congenital neurobehavioral disorder characterized by rounded face, low forehead, almond shaped eyes, squinting, hypogonadism, hypotonia, insatiable appetite leading to obesity, and mental retardation [icd9data.com]

    Dysmorphic findings in a child with Prader-Willi syndrome include narrowing of the temples, almond-shaped eyes, strabismus, and a thin upper lip. Figure 1. [aafp.org]

  • Strabismus

    Strabismus was present in 25 (54%) patients: 22 (48%) patients had esotropia and three (7%) had exotropia. Nine patients either received or required strabismus surgery. [ncbi.nlm.nih.gov]

    Clinical manifestations include MENTAL RETARDATION; MUSCULAR HYPOTONIA; HYPERPHAGIA; OBESITY; short stature; HYPOGONADISM; STRABISMUS; and HYPERSOMNOLENCE. [web.archive.org]

    Clinical manifestations include mental retardation; muscular hypotonia; hyperphagia; obesity; short stature; hypogonadism; strabismus; and hypersomnolence. [icd9data.com]

  • Esotropia

    Strabismus was present in 25 (54%) patients: 22 (48%) patients had esotropia and three (7%) had exotropia. Nine patients either received or required strabismus surgery. [ncbi.nlm.nih.gov]

    He had bilateral gynecomastia, decreased biparietal diameter, almond shaped eyes with esotropia. He had hypogonadism and also had mild cognitive impairment. He did not have any proximal myopathy or other focal neurological deficits. [jfmpc.com]

    […] obsessive-compulsive behavior, stubbornness, rigidity, stealing, and lying Sleep disturbance or sleep apnea Short stature by age 15 years (based on the individual family) Hypopigmentation Hands and feet small for height/age Narrow hands with straight ulnar border Esotropia [arupconsult.com]

    […] scrotum, and small testes in males; hypoplastic labia minora and clitoris in females; and pubertal deficiency) Infantile central hypotonia Rapid weight gain between 1 and 6 years of age Minor criteria Decreased fetal movement and infantile lethargy Esotropia [aafp.org]

  • Blonde Hair

    Someone with PWS may also be born with distinct facial features including almond-shaped eyes, a narrowing of the head, a thin upper-lip, light skin and hair (50% of people have fair skin, blonde hair and blue eyes, regardless of what their family members [aruma.com.au]

    Around half of all children with Prader-Willi syndrome will have fair skin, blonde hair and blue eyes, regardless of what their family members look like.Children with Prader-Willi syndrome are delayed in all aspects of development, reaching developmental [betterhealth.vic.gov.au]

    The child usually has blue eyes and blond hair. They tend to lag behind other children in the transition to solid food. [patient.info]

  • Fair Complexion

    There were no facial dysmorphic features except that he had fair complexion. He had bilateral gynecomastia. Both hands and feet were relative small (Figure 1). There was only scanty axillary and pubic hair. [hindawi.com]

  • Reduced Fetal Movement

    In fetal life: Reduced fetal movements and abnormal position Polyhydramnios Requirement for caesarean section In neonates and children: Feeding difficulties (poor suckling reflex) Delayed developmental motor milestones Delayed onset of speech Thick saliva [symptoma.com]

    Prenatal Development Most pregnancies of children with PWS are uneventful, though reduced fetal movement is noted in the majority of PWS pregnancies. [ncbi.nlm.nih.gov]

  • Small Hand

    hands and feet, mild dysmorphology, and behavior problems which can be severe. [curlie.org]

    The clinical appearance of PWS includes dysmorphic facial features with almond-shaped eyes, a narrow bifrontal diameter, and a thin upper lip; short stature; central obesity; and small hands and feet. [ncbi.nlm.nih.gov]

    First described by Prader, Labhardt and Willi in 1956 on the basis of nine children with the tetrad of small stature, mental retardation, obesity and small hands and feet. [whonamedit.com]

  • Muscle Hypotonia

    Because of weak muscles (hypotonia), the infant is not able to drink from a bottle and may need special feeding techniques or tube feedings until his/her muscles become stronger. [rarediseases.about.com]

    (hypotonia) learning difficulties lack of sexual development behavioural problems, such as temper tantrums or stubbornness Read more about symptoms of Prader-Willi syndrome. [nhs.uk]

    A newborn with PWS tends to weigh less than normal, has weak muscles (hypotonia), and may find sucking difficult. Between the ages of 2 and 5 years individuals start developing a voracious appetite. Some, however, may start later. [web.archive.org]

    […] in part, plays a role in muscle hypotonia and weakness. [medicalhomeportal.org]

  • Round Face

    (menkes, textbook of child neurology, 5th ed, p229) Congenital neurobehavioral disorder characterized by rounded face, low forehead, almond shaped eyes, squinting, hypogonadism, hypotonia, insatiable appetite leading to obesity, and mental retardation [icd9data.com]

    (Menkes, Textbook of Child Neurology, 5th ed, p229) Definition (CSP) congenital neurobehavioral disorder characterized by rounded face, low forehead, almond shaped eyes, squinting, hypogonadism, hypotonia, insatiable appetite leading to obesity, and mental [fpnotebook.com]

    face/full cheeks (55%), and skull features (53%). [frontiersin.org]

    Affected individuals also have mild-moderate intellectual impairment, hypogonadism, and characteristic facies consisting of a narrow bifrontal diameter, almond-shaped eyes, a round face, and downturned corners of the mouth. [medscape.com]

  • Low Forehead

    (menkes, textbook of child neurology, 5th ed, p229) Congenital neurobehavioral disorder characterized by rounded face, low forehead, almond shaped eyes, squinting, hypogonadism, hypotonia, insatiable appetite leading to obesity, and mental retardation [icd9data.com]

    (Menkes, Textbook of Child Neurology, 5th ed, p229) Definition (CSP) congenital neurobehavioral disorder characterized by rounded face, low forehead, almond shaped eyes, squinting, hypogonadism, hypotonia, insatiable appetite leading to obesity, and mental [fpnotebook.com]

    He also presented low forehead, almond-shaped eyes, thin upper lip, high-arched palate, small hands, tapering fingers and hepatomegaly. Blood exams were normal. An abdomen ultrasound scan revealed the presence of fatty liver disease. [ijponline.biomedcentral.com]

  • Hunger

    Mindfulness-based strategies included mindful eating, visualizing and labeling hunger, and rapidly shifting attention away from hunger by engaging in Meditation on the Soles of the Feet. [ncbi.nlm.nih.gov]

    A key feature of Prader-Willi syndrome is a constant sense of hunger that usually begins at about 2 years of age. [mayoclinic.org]

    It causes poor muscle tone, low levels of sex hormones and a constant feeling of hunger. The part of the brain that controls feelings of fullness or hunger does not work properly in people with pws. [icd9data.com]

    Hypothalamic dysfunction underlies most of the symptoms of Prader-Willi syndrome, leading to disturbances of sleep-wake cycles, sexual characteristics, hunger and satiety, pain and temperature sensations. [symptoma.com]

    It causes unrelenting hunger and excessive eating, a root cause of morbidity and mortality in PWS patients. [uab.edu]

  • Emotional Lability

    Prader-Willi syndrome (PWS) is an uncommon genetic disorder characterized by mental retardation, decreased muscle tone, short stature, emotional lability and an insatiable appetite which can lead to life-threatening obesity. [ncbi.nlm.nih.gov]

    In addition, PWS children exhibit several other behavioral problems, including skin picking, repetitive behaviors, difficulty with routine changes and great emotional lability. Several PWS children are also diagnosed as autists. [metinalista.si]

    lability; and skin picking [62]. [ijpeonline.biomedcentral.com]

    Characteristic symptoms may include temper tantrums, oppositional behavior and stubbornness, emotional lability, and obsessive ruminations or compulsive behaviors such as skin-picking (2). [ajp.psychiatryonline.org]

  • Emotional Outbursts

    Does Your Child Have Emotional Outbursts? See a Full List of Topics! [thedoctorstv.com]

    Emotional outbursts. Mood changes. Obsessive or compulsive behaviors. Stubbornness. To help manage these behavioral issues, daily routines, firm rules and positive rewards can help. [gillettechildrens.org]

  • Cryptorchidism

    Features included cryptorchidism in 94% males, preterm birth (26%), birthweight 28 days: 1-12 months in seven; and 3.75-10.5 years in five. [ncbi.nlm.nih.gov]

    […] obesity Hyperphagia Characteristic facial features – narrow bifrontal diameter, almond-shaped palpebral fissures, downturned mouth Hypogonadism manifestations Genital hypoplasia Females – small labia minora and clitoris Males – hypoplastic scrotum and cryptorchidism [arupconsult.com]

  • Clitoral Hypoplasia

    hypoplasia Small clitoris Underdeveloped clit [ more ] 0000060 Cutaneous photosensitivity Photosensitive skin Photosensitive skin rashes Photosensitivity Sensitivity to sunlight Skin photosensitivity Sun sensitivity [ more ] 0000992 Decreased circulating [rarediseases.info.nih.gov]

    History See the list below: Infants with Prader-Willi syndrome (PWS) commonly exhibit hypotonia, poor suck (with requirement of gavage feedings), weak cry, and genital hypoplasia (eg, cryptorchidism, scrotal hypoplasia, clitoral hypoplasia). [37] Neonatal [emedicine.medscape.com]

    Hypogonadism with genital hypoplasia (cryptorchidism, scrotal or clitoral hypoplasia) can be identified in the newborn period. [ijpeonline.biomedcentral.com]

    hypoplasia 76%, primary amenorrhea 56%, spontaneous menarche (mostly spotting) 44% of those older than 15 years; in both sexes: premature pubarche 14%, and precocious puberty 3.6% (one male and two females). [nature.com]

  • Small Scrotum

    All 14 boys had a small scrotum, including nine with cryptorchidism. Diagnoses were made with microarray comparative genomic hybridization. All 20 infants required feeding tubes. [ncbi.nlm.nih.gov]

  • Behavior Problem

    GABA levels were significantly lower in the participants with PWS who had clinically significant emotional and behavioral problems relative to typically developing control participants and participants with PWS who did not have emotional and behavioral [ncbi.nlm.nih.gov]

    problems which can be severe. [curlie.org]

    These disorders can result in excessive daytime sleepiness and worsen behavior problems. Other signs and symptoms. [mayoclinic.org]

  • Tantrums

    Important improvements were achieved and maintained including weight loss, decreased need for supplemental oxygen, greater exercise tolerance, and fewer tantrums. [ncbi.nlm.nih.gov]

    Changes in behaviour may also become evident over time with tantrums, stubbornness and mood swings occurring. Treatment There is no cure for Prader Willi syndrome. [brainfoundation.org.au]

  • Neonatal Hypotonia

    Hyperphagia, intellectual disabilities/behavioral disorders, neonatal hypotonia, and hypogonadism are cardinal features for PWS. [ncbi.nlm.nih.gov]

  • Sleep Disturbance

    Long-term modafinil therapy may ameliorate the sleep disturbances of Prader-Willi syndrome and should be the focus of future clinical trials. [ncbi.nlm.nih.gov]

    Some of the behaviors which are common to both Prader-Willi Syndrome and autism are: delays in language and motor development, learning disabilities, feeding problems in infancy, sleep disturbances, skin picking, temper tantrums, and a high pain threshold [autism.com]

    disturbances Poor bone health Scoliosis Decreased sensitivity to pain Poor control of body temperature Gastrointestinal issues including decreased motility and gastroparesis Self-injurious behavior such as skin picking Increased risk of central adrenal [youtube.com]

    The neurobehavioral phenotype in individuals with PWS includes hyperphagia, temper tantrums, aggression, specific repetitive and ritualistic behavior, stealing and lying, skin picking, mood and sleep disturbances. [genedx.com]

    Behavioral features in childhood include temper tantrums, high pain threshold, sleep disturbances, and skin picking. [aafp.org]

  • Lethargy

    Prader-Willi syndrome (PWS) is characterized by infantile lethargy and hypotonia causing poor feeding and failure to thrive, childhood obesity, short stature, and hypogonadism. [ncbi.nlm.nih.gov]

    […] abnormal position Polyhydramnios Requirement for caesarean section In neonates and children: Feeding difficulties (poor suckling reflex) Delayed developmental motor milestones Delayed onset of speech Thick saliva Weak cry Excessive sleeping Hypotonia Lethargy [symptoma.com]

    This can cause: Poor feeding (inability to suck) Decreased movement and lethargy Weak cry Poor reflexes Additionally, 90 to 100 percent of infants with the syndrome have delayed motor development, requiring about twice as long to achieve developmental [everydayhealth.com]

    – small labia minora and clitoris Males – hypoplastic scrotum and cryptorchidism Incomplete and delayed puberty Infertility Developmental delay (mild to moderate), multiple learning disabilities Minor criteria Decreased fetal movement and infantile lethargy [arupconsult.com]

    […] hypoplastic scrotum, and small testes in males; hypoplastic labia minora and clitoris in females; and pubertal deficiency) Infantile central hypotonia Rapid weight gain between 1 and 6 years of age Minor criteria Decreased fetal movement and infantile lethargy [aafp.org]

Diagnosis is established with the help of the following investigations.

  • Prenatal DNA testing for gene abnormalities
  • Southern blotting for DNA methylation patterns
  • Polymerase chain reaction (PCR)
  • Parental DNA sampling for disomy
  • Fluorescent in situ hybridization (FISH)
  • Chorionic villus sampling and amniocentesis
  • Screening tests for serum insulin like growth factor-1 (IGF-1), growth hormone levels and glycosylated hemoglobin
  • Thyroid function tests
  • Magnetic Resonance Imaging (MRI) in case of (hypopituitarism)
  • Serial dual energy x-ray absorptiometry (DEXA) scanning (osteoporosis)
  • X-ray of the chest
  • Abdominal ultrasonography
  • Computerized Tomography (CT) scans

There is no cure for Prader-Willi syndrome as it is a gene defect. The treatment is done for the management of acute symptoms of the disease [3]. It consists of the following.

  • Growth hormone therapy helps improve the skeletal and muscle defects of Prader-Willi syndrome, in particular hypotonia [9][10].
  • Vitamin D supplementation in these patients is associated with good results.
  • Surgical management of respiratory difficulties may be indicated if the symptoms are severe. Tracheostomy may need to be done.

The condition is associated with development of secondary disorders like diabetes mellitus which can lead to comorbidities. Gastric and respiratory problems may lead to death. The overall prognosis is poor.

The syndrome arises due to deletion of genes on the chromosome 15 in the region 15q11-13 along with gene imprinting in maternal chromosomes [1]. Mutations or translocation of the genes may also give rise to Prader-Willi syndrome.

Prader-Willi syndrome occurs in about 1 in 10,000 to 1 in 25,000 newborns. The occurrence of this disease is sporadic. It affects male and females equally. No gender, racial or ethnic predisposition has been found.

The syndrome is not heritable as this is an acquired anomaly of the embryonic life. However, rare genetic changes in Prader-Willi syndrome can be passed on. Recurrence of the syndrome in siblings is uncommon.

Deletion of genes on the chromosome 15 in the region 15q11-13 leads to this abnormality. The underlying gene defect can occur by any of the three pathways:

  • Deletion of genes in the paternal chromosomes.
  • Genomic imprinting (and resultant silencing) of corresponding genes in the maternal chromosomal set.
  • Uniparental disomy (UPD) can be another of the mechanisms of gene defects.

These genes usually code for certain small nucleolar RNAs (snoRNAs) which have regulatory as well as other functions.
Loss of SNORD116 gene cluster and OCA2 genes is common in Prader-Willi syndrome. This leads to hypopigmentation of skin and hair that is associated with the disorder.

Hypothalamic dysfunction underlies most of the symptoms of Prader-Willi syndrome, leading to disturbances of sleep-wake cycles, sexual characteristics, hunger and satiety, pain and temperature sensations.

The following measures should be adopted in order to minimize the morbidity from Prader-Willi syndrome.

  • Parental genetic counseling should be done.
  • Due to poor muscle power, neonates should be handled and picked up carefully.
  • Strict dietary control should be observed for prevention of obesity. A balanced diet should be followed. All essential nutrients should be made a part of diet. Access of child to food should be restricted to prevent bouts of overeating and to keep their weight in check.
  • Muscle activity like sports should be encouraged to overcome hypotonia and motor problems.
  • Steroid therapy should be avoided as it tends to exacerbate the behavioral dysfunction
  • Monitoring of children should be done to prevent respiratory and gastric difficulties.
  • A strict sleeping routine should be followed to avoid daytime sleepiness and other sleep-related abnormalities.
  • Behavioral problems should be handled with patience. If needed, psychiatric help should be sought.
  • Parental screening tests should be carried out to assess the risk of recurrence of the disease with further pregnancies.

Prader-Willi syndrome (PWS), also known as Prader-Labhart-Willi syndrome, is a rare genetic disorder that arises due to genetic abnormalities. It is a multiphasic disorder that can lead to obesity in children.

Delayed onset of development is commonly observed in the cases of PWS. Behavioral and cognitive problems are also common in such children along with some degree of intellectual deficit.

Prader-Willi syndrome (PWS) develops as a result of genetic abnormalities due which the child suffers from late speech development, decrease muscle power, insatiable hunger and overeating bouts, obesity, excessive sleeping, weakness and mental retardation. Short stature and short hands and feet are typical of PWS. Growth retardation is common and such children fail to thrive. Puberty is delayed in patients of Prader-Willi syndrome and infertility is common.

Testing should be done to check for gene abnormalities before birth so that appropriate measures can be taken beforehand. The disease is rarely passed onto the next generation and is compatible with life but a lot of abnormalities develop in such patients. Presence of Prader-Willi syndrome in one child does not mean that further pregnancies will result in recurrence of the syndrome.

  1. Cassidy SB. Prader-Willi syndrome. Characteristics, management, and etiology. The Alabama journal of medical sciences. Apr 1987;24(2):169-175.
  2. Witkowski R, Ullrich E, Pietsch P, et al. [Infant hypotonia, obesity, hypogenitalism and oligophrenia--new viewpoints on the etiology and symptoms of Prader-Willi syndrome]. Psychiatrie, Neurologie, und medizinische Psychologie. May 1985;37(5):255-261.
  3. Zipf WB. Prader-Willi syndrome: the care and treatment of infants, children, and adults. Advances in pediatrics. 2004;51:409-434.
  4. Altman K, Bondy A, Hirsch G. Behavioral treatment of obesity in patients with Prader-Willi syndrome. Journal of behavioral medicine. Dec 1978;1(4):403-412.
  5. De Peppo F, Di Giorgio G, Germani M, et al. BioEnterics intragastric balloon for treatment of morbid obesity in Prader-Willi syndrome: specific risks and benefits. Obesity surgery. Nov 2008;18(11):1443-1449.
  6. Scheimann A, Butler MG, Stevenson D, Miller JL, Cuffari C, Klish WJ. "Efficacy of laparoscopic sleeve gastrectomy as a stand-alone technique for children with morbid obesity" and "BioEnterics intragastric balloon for treatment of morbid obesity in Prader-Willi syndrome: specific risks and benefits". Obesity surgery. May 2009;19(5):671-672; author reply 673.
  7. Eiholzer U, Grieser J, Schlumpf M, l'Allemand D. Clinical effects of treatment for hypogonadism in male adolescents with Prader-Labhart-Willi syndrome. Hormone research. 2007;68(4):178-184.
  8. Benarroch F, Hirsch HJ, Genstil L, Landau YE, Gross-Tsur V. Prader-Willi syndrome: medical prevention and behavioral challenges. Child and adolescent psychiatric clinics of North America. Jul 2007;16(3):695-708.
  9. Hoybye C, Hilding A, Jacobsson H, Thoren M. Growth hormone treatment improves body composition in adults with Prader-Willi syndrome. Clinical endocrinology. May 2003;58(5):653-661.
  10. Craig ME, Cowell CT, Larsson P, et al. Growth hormone treatment and adverse events in Prader-Willi syndrome: data from KIGS (the Pfizer International Growth Database). Clinical endocrinology. Aug 2006;65(2):178-185.

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