Growth hormone treatment for Prader-Willi syndrome: A review

Common and uncommon mouse models of growth hormone deficiency

Mouse models of growth hormone deficiency (GHD) have provided important tools for uncovering the various actions of GH. Nearly 100 years of research using these mouse lines has greatly enhanced our knowledge of the GH/IGF-1 axis. Some of the shared phenotypes of the five "common" mouse models of GHD include reduced body size, delayed sexual maturation, decreased fertility, reduced muscle mass, increased adiposity, and enhanced insulin sensitivity. Since these common mouse lines outlive their normal-sized littermates - and have protection from age-associated disease - they have become important fixtures in the aging field. On the other hand, the twelve "uncommon" mouse models of GHD described herein have tremendously divergent health outcomes ranging from beneficial aging phenotypes (similar to those described for the common models) to extremely detrimental features (such as improper development of the CNS, numerous sensory organ defects, and embryonic lethality). Moreover, advancements in next generation sequencing technologies have led to the identification of an expanding array of genes that are recognized as causative agents to numerous rare syndromes with concomitant GHD. Accordingly, this review provides researchers with a comprehensive up-to-date collection of the common and uncommon mouse models of GHD that have been used to study various aspects of physiology and metabolism associated with multiple forms of GHD. For each mouse line presented, the closest comparable human syndromes are discussed providing important parallels to the clinic.

Prader-Willi syndrome in a large sample from Spain: general features, obesity and regular use of psychotropic medication

BACKGROUND

Prader-Willi syndrome (PWS), a genetically determined disorder, the most frequent cause of early onset obesity, is associated with physical and cognitive dysfunctions and behavioural disturbances; these disturbances are frequently treated with psychotropic medication. The aim of this cross-sectional study was to describe the characteristics of the first large national sample of persons with PWS in Spain and analyse the relationships of those characteristics with key demographic and clinical factors, particularly with obesity and the regular use of psychotropic medication.

METHODS

Participants were recruited among all members of the Spanish Prader-Willi Association who agreed to take part in the study and fulfilled its inclusion criteria. Family and patient demographic features, family size and birth order, intelligence quotient (IQ), anthropometric measures, lifestyle habits, behavioural disturbances (with the Aberrant Behavior Checklist) and clinical data, as well as use of psychotropic drugs and their side effects (with the UKU scale), were collected in genetically confirmed cases of PWS. Bivariate and logistic regression analyses were used for determining the associations of demographic and clinical factors with both obesity and the regular use of psychotropic medication.

RESULTS

The cohort included 177 participants (aged 6-48 years), that is, 90 (50.8%) males and 87 (49.2%) females. Behavioural disturbances were present in a range of 75% to 93% of participants; psychotropic medication was prescribed to 81 (45.8%) of them. Number of siblings showed a direct correlation with IQ, especially among males, and inappropriate speech was more intense in only-child females. Obesity was, in parallel, strongly associated with ascending age and with not being currently under growth hormone (GH) treatment. Participants taking any psychotropic medication were characterised by more frequent age ≥30 years, high level of hyperactivity and a psychiatric diagnosis.

CONCLUSIONS

Characterisation of persons with PWS in Spain confirms their physical and behavioural phenotype and supports the long-term application of GH therapy and the rational use of psychotropic medication.

Early psychomotor development and growth hormone therapy in children with Prader-Willi syndrome: a review

Prader-Willi syndrome (PWS) is a rare genetic disorder caused by the loss of imprinted gene expression on the paternal chromosome 15q11-q13. PWS is characterized by varying degrees of early psychomotor developmental deficits, primarily in cognition, language, and motor development. This review summarizes the early mental cognitive development, language development, and motor development in patients with PWS, compares the correlation of genotype with phenotype, and provides an update regarding the effects and concerns related to potential main side effects of treatment with recombinant human growth hormone on early psycho-cognitive and motor function development along with the linear growth and body composition of children with PWS.Conclusion: Early psychomotor development is strongly correlated with the prognosis of patients with PWS; moreover, current studies support that the initiation of interventions at an early age can exert significant beneficial effects on enhancing the cognitive and linguistic development of patients with PWS and allow them to "catch up" with motor development.  What is Known: • Prader-Willi syndrome is a rare genetic disorder characterized by multisystem damage, and children with Prader-Willi syndrome are typically characterized by early developmental delays, specifically in the areas of cognitive and motor development. • Recombinant human growth hormone therapy is the only medical treatment approved for Prader-Willi syndrome. What is New: • Extensive presentation of psycho-cognitive and motor development features and genotype-phenotype correlation in children with Prader-Willi syndrome.  • The effects of growth hormone on early psychomotor development in children with Prader-Willi syndrome were thoroughly reviewed, including their short- and long-term outcomes and any associated adverse effects.

Prader–Willi Syndrome: Possibilities of Weight Gain Prevention and Treatment

Prader–Willi syndrome (PWS) is a complex genetic disorder which involves the endocrine and neurologic systems, metabolism, and behavior. The aim of this paper is to summarize current knowledge on dietary management and treatment of PWS and, in particular, to prevent excessive weight gain. Growth hormone (GH) therapy is the recommended standard treatment for PWS children, because it improves body composition (by changing the proportion of body fat and lean body mass specifically by increasing muscle mass and energy expenditure), linear growth, and in infants, it promotes psychomotor and IQ development. In early childhood, the predominant symptom is hyperphagia which can lead to early onset, severe obesity with different obesity-related comorbidities. There are several studies on anti-obesity medications (metformin, topiramate, liraglutide, setmelanotide). However, these are still limited, and no widely accepted consensus guideline exists concerning these drugs in children with PWS. Until there is a specific treatment for hyperphagia and weight gain, weight must be controlled with the help of diet and exercise. Below the age of one year, children with PWS have no desire to eat and will often fail to thrive, despite adequate calories. After the age of two years, weight begins to increase without a change in calorie intake. Appetite increases later, gradually, and becomes insatiable. Managing the progression of different nutritional phases (0–4) is really important and can delay the early onset of severe obesity. Multidisciplinary approaches are crucial in the diagnosis and lifelong follow-up, which will determine the quality of life of these patients.

Dietary Conjugated Linoleic Acid Reduces Body Weight and Fat in Snord116m+/p- and Snord116m-/p- Mouse Models of Prader-Willi Syndrome

Prader–Willi Syndrome (PWS) is a human genetic condition that affects up to 1 in 10,000 live births. Affected infants present with hypotonia and developmental delay. Hyperphagia and increasing body weight follow unless drastic calorie restriction is initiated. Recently, our laboratory showed that one of the genes in the deleted locus causative for PWS, Snord116, maintains increased expression of hypothalamic Nhlh2, a basic helix–loop–helix transcription factor. We have previously also shown that obese mice with a deletion of Nhlh2 respond to a conjugated linoleic acid (CLA) diet with weight and fat loss. In this study, we investigated whether mice with a paternal deletion of Snord116 (Snord116^m+/p−) would respond similarly. We found that while Snord116^m+/p− mice and mice with a deletion of both Snord116 alleles were not significantly obese on a high-fat diet, they did lose body weight and fat on a high-fat/CLA diet, suggesting that the genotype did not interfere with CLA actions. There were no changes in food intake or metabolic rate, and only moderate differences in exercise performance. RNA-seq and microbiome analyses identified hypothalamic mRNAs, and differentially populated gut bacteria, that support future mechanistic analyses. CLA may be useful as a food additive to reduce obesity in humans with PWS.

Associations Between Hyperphagia, Symptoms of Sleep Breathing Disorder, Behaviour Difficulties and Caregiver Well-Being in Prader-Willi Syndrome: A Preliminary Study

Prader-Willi syndrome (PWS) is a rare genetic disorder characterised by neurodevelopmental delays, hyperphagia, difficulties with social communication and challenging behaviours. Individuals require intensive supervision from caregivers which may negatively affect caregiver quality of life. This study used data collected in the Australasian PWS Registry (n = 50, mean age 11.2 years) to evaluate associations between child behaviours and caregiver mental well-being. Symptoms of sleep-related breathing disorder, child depression and social difficulties were associated with poorer caregiver mental and physical well-being. Growth hormone therapy use was associated with better caregiver mental and physical well-being. Optimising management of problematic behaviours and sleep disturbances have the potential to support caregivers who are the most vital network of support for individuals affected by PWS.

Effects of Childhood Multidisciplinary Care and Growth Hormone Treatment on Health Problems in Adults with Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is a complex hypothalamic disorder. Features of PWS include hyperphagia, hypotonia, intellectual disability, and pituitary hormone deficiencies. The combination of growth hormone treatment and multidisciplinary care (GHMDc) has greatly improved the health of children with PWS. Little is known about the effects of childhood GHMDc on health outcomes in adulthood. We retrospectively collected clinical data of 109 adults with PWS. Thirty-nine had received GHMDc during childhood and adolescence (GHMDc+ group) and sixty-three had never received growth hormone treatment (GHt) nor multidisciplinary care (GHMDc− group). Our systematic screening revealed fewer undetected health problems in the GHMDc+ group (10%) than in the GHMDc− group (84%). All health problems revealed in the GHMDc+ group had developed between the last visit to the paediatric and the first visit to the adult clinic and/or did not require treatment. Mean BMI and the prevalence of diabetes mellitus type 2 were significantly lower in the GHMDc+ group compared to the GHMDc− group. As all patients who received GHt were treated in a multidisciplinary setting, it is unknown which effects are the result of GHt and which are the result of multidisciplinary care. However, our data clearly show that the combination of both has beneficial effects. Therefore, we recommend continuing GHMDc after patients with PWS have reached adult age.