A survey on Prader-Willi syndrome in the Italian population: prevalence of historical and clinical signs

Endocrine features of Prader-Willi syndrome: a narrative review focusing on genotype-phenotype correlation

Prader-Willi syndrome (PWS) is a complex genetic disorder caused by three different types of molecular genetic abnormalities. The most common defect is a deletion on the paternal 15q11-q13 chromosome, which is seen in about 60% of individuals. The next most common abnormality is maternal disomy 15, found in around 35% of cases, and a defect in the imprinting center that controls the activity of certain genes on chromosome 15, seen in 1-3% of cases. Individuals with PWS typically experience issues with the hypothalamic-pituitary axis, leading to excessive hunger (hyperphagia), severe obesity, various endocrine disorders, and intellectual disability. Differences in physical and behavioral characteristics between patients with PWS due to deletion versus those with maternal disomy are discussed in literature. Patients with maternal disomy tend to have more frequent neurodevelopmental problems, such as autistic traits and behavioral issues, and generally have higher IQ levels compared to those with deletion of the critical PWS region. This has led us to review the pertinent literature to investigate the possibility of establishing connections between the genetic abnormalities and the endocrine disorders experienced by PWS patients, in order to develop more targeted diagnostic and treatment protocols. In this review, we will review the current state of clinical studies focusing on endocrine disorders in individuals with PWS patients, with a specific focus on the various genetic causes. We will look at topics such as neonatal anthropometry, thyroid issues, adrenal problems, hypogonadism, bone metabolism abnormalities, metabolic syndrome resulting from severe obesity caused by hyperphagia, deficiencies in the GH/IGF-1 axis, and the corresponding responses to treatment.

Genotype-phenotype correlation in Prader-Willi syndrome: A large-sample analysis in China

The genotype-phenotype relationship in PWS patients is important for a better understanding of the clinical phenotype and clinical characteristics of different genotypes of PWS in children. We aimed to explore the influence of specific gene changes on the clinical symptoms of PWS and the value of early screening and early intervention of the condition. All data in this study were extracted from the database of the XiaoPang Weili Rare Disease Care Center. The collected information included basic demographics, maternal pregnancy information, endocrine abnormalities, growth and development abnormalities, and other clinical phenotypes. The relationships between genotypes and phenotypes in the major categories of PWS were analyzed. A total of 586 PWS cases with confirmed molecular diagnosis and genotyping were included in this study. Among them, 83.8% belonged to the deletion type, 10.9% the uniparental disomy (UPD) type, and 5.3% the imprinting defect (ID) type. Age-wide comparison among the three groups: The rate of hypopigmentation in the deletion group was higher than that in the UPD group (88.8% vs. 60.9%; p < 0.05); A total of 62 patients (14.2%) had epilepsy; and no statistical significance was found among the three groups (p = 0.110). Age-wide comparison between the deletion and non-deletion types: the rate of skin hypopigmentation and epilepsy in the deletion group was significantly higher than that in the non-deletion group (88.8% vs. 68.4%, p < 0.001; 15.9% vs. 7.6%, p = 0.040). The intergroup comparison for the >2-year age group: there were significant intergroup differences in the language development delay among the three groups (p < 0.001). The incidence of delayed language development was the highest in the deletion group, followed by the UPD group, and the lowest in the ID group. The rates of obesity and hyperphagia in the deletion group were also higher than those in the non-deletion group (71.1% vs. 58.9%, p = 0.041; 75.7% vs. 62.0%, p = 0.016). There are significant differences in the rates of skin hypopigmentation and language developmental delay among the deletion, UPD, and ID genotypes. The patients with deletion type had significantly higher rates of lighter skin color, obesity, hyperphagia, language developmental delay, and epilepsy. The results of this study will help clinicians better understand the impact of different PWS molecular etiologies on specific phenotypes.

Three pediatric cases of symptomatic hyponatremia in Prader-Willi syndrome

OBJECTIVES

A recent large retrospective cohort study of cases of hyponatremia in Prader-Willi syndrome (PWS), conducted at nine reference centers, showed that severe hyponatremia was rare in PWS (0.5%); furthermore, all cases involved adults. Here, we describe three pediatric cases of severe hyponatremia in PWS, with neurological symptoms.

CASE PRESENTATION

The cases involved two girls and one boy, and only one patient showed uniparental disomy. All patients had hyponatremia during infancy and presented with clinical symptoms, such as convulsions. All three patients improved with intravenous fluids and fluid restriction, with no sequelae.

CONCLUSIONS

We report three pediatric cases of symptomatic hyponatremia of unknown cause in PWS. In patients with PWS, especially those with neurological symptoms such as convulsions, it is necessary to take hyponatremia into consideration.

Robustness of Distinctive Facial Features in Prader-Willi Syndrome: A Stereophotogrammetric Analysis and Association with Clinical and Biochemical Markers in Adult Individuals

Background: Prader-Willi syndrome (PWS) is a rare genomic imprinting disorder associated to a complex neurodevelopmental phenotype and a distinctive facial appearance. The study investigated the relationships between the quantitative facial dysmorphism in PWS and clinical and biochemical markers of the disease and its treatment. Methods: Facial images of 15 Caucasian adult individuals with PWS (8 males, 42 ± 5 years; 7 females, 37 ± 8 years; BMI 38.87 ± 8.92 kg/m2) were acquired through stereophotogrammetry. From the 3D coordinates of 38 landmarks, linear distances and angles were calculated; they were expressed as z-score values by referring to 403 healthy subjects matched for age and sex and compared by Student’s t-test with Bonferroni correction for multiple testing. Patients underwent auxological and biochemical assessment of endocrine/metabolic dysfunction and nocturnal respiratory function. An exploratory correlation analysis was performed to investigate their associations with the facial phenotype; uncorrected p-values were used. Results and Conclusions: Individuals with PWS showed decreased bifrontal diameter, facial depths, palpebral fissures, mandibular ramus length, lower vermillion height, and modified relative position of exocanthia and nasion. Since these characteristics did not show any associations with clinical and biochemical markers of PWS, they could constitute robust distinctive facial features and contribute to the diagnosis of the disorder. Individuals with PWS showed also a larger mandibular width with smaller gonial angles, thinner upper vermillion, greater inclination of the orbit relative to the Frankfurt plane, and a smaller angle of the auricles versus the facial midplane. Relationships between these facial anthropometric features and body composition, glucidic metabolism indexes, nocturnal hypoxemia episodes, or duration of GH treatment were found, suggesting their potentially useful role in the clinical monitoring and management of the disease. However, they need to be confirmed by subsequent dedicated studies.

High Prevalence of Scoliosis in a Large Cohort of Patients with Prader-Willi Syndrome

The characteristics of scoliosis were investigated in a large cohort of children and adults with Prader–Willi syndrome (PWS), analysing the role of age, gender, puberty, body mass index (BMI), genotype and growth hormone therapy (GHT) on its onset and severity. A retrospective cross-sectional study was performed in 180 patients with genetically confirmed PWS (96 females), aged 17.6 ± 12 years. Eighty-five subjects (47%) were obese. One hundred and fifty subjects (83.3%) were on GHT, while 30 patients had never been treated. Overall, 150 subjects (83.3%) were affected by scoliosis, 80.2% of children and adolescents and 87.8% of adults. A mild degree of scoliosis was observed in 58 patients (38.7%), moderate in 43 (28.7%) and severe in 49 (32.6%). Median age at diagnosis of scoliosis was 6.3 years, while the severe forms were diagnosed earlier (median age: 3.8 years). The cumulative probability at 5 years of age was equal to 0.403 and almost doubled at 15 years. No significant associations were found between scoliosis and genotype, gender, pubertal stage, GHT and BMI. A corset was prescribed to 75 subjects (50%) at a median age of 7.5 years, while 26 subjects (17.3%) underwent surgery at a median age of 13.1 years. Our data indicate that scoliosis is one of the major concerns for PWS patients that increases with age, and therefore suggest the need for regular systematic monitoring of spinal deformity from paediatric age.

Psychiatric behavioral effect and characteristics of type 2 diabetes mellitus on Japanese patients with Prader-Willi syndrome: a preliminary retrospective study

OBJECTIVES

In recent years, research on behavioral and psychiatric problems of adults with Prader-Willi syndrome (PWS) has gained attention. However, no report is available regarding the relationship between psychiatric illness and type 2 diabetes mellitus (T2DM) in patients with PWS. Therefore, we evaluated a behavioral assessment to address the lack of data on the association between psychiatric behavior and T2DM.

METHODS

This was a retrospective single-center study of patients with PWS. Patients with PWS whose blood tests were performed in our hospital between January 2018 and December 2019 and aged >10 years were included. We evaluated the data, including the behavioral patterns of Japanese PWS patients with T2DM.

RESULTS

Overall, 114 patients were evaluated; 33 patients (28.9%) developed T2DM. The age of T2DM onset was 18.0 years (interquartile range [IQR], 14.6-21.4 years). The median body mass index at T2DM onset was 33.7 kg/m² (IQR, 30.0-37.4 kg/m²). Between-group comparisons of the intelligence quotient, Food-Related Problem Questionnaire (FRPQ), and Japanese versions of the Short Sensory Profile and Aberrant Behavior Checklist showed a significant difference only in FRPQ scores (p=0.003).

CONCLUSIONS

The occurrence of T2DM among Japanese patients with PWS remains high. Only the FRPQ was significantly different between the T2DM and the non-T2DM group.

Caring and living with Prader-Willi syndrome in Italy: integrating children, adults and parents' experiences through a multicentre narrative medicine research

OBJECTIVES

Prader-Willi syndrome (PWS) significantly impacts health-related quality of life; however, its relational and existential aspects remain unknown in Italian clinical and social debate. The project aimed to investigate the impact of PWS on illness experience through narrative medicine (NM) to understand the daily life, needs and resources of patients with PWS and their caregivers, and to furnish insights for clinical practice.

DESIGN AND SETTING

The project involved 10 medical centres of the Italian Network for Rare Diseases and PWS family associations and targeted underage and adult patients with PWS and their caregivers. Written interviews, composed by a sociodemographic survey and a narrative, were collected through the project's website. Three dedicated illness plots employed evocative and open words to facilitate individual expression and to encourage reflection. Narratives were analysed through NVivo software. Researchers discussed the results with the project's steering committee.

PARTICIPANTS

Twenty-one children and adolescents and 34 adults with PWS joined the project, as well as 138 caregivers. A PWS diagnosis or the caregiving of a patient with PWS older than 5 years represented the eligibility criteria, as well as the willingness to share their illness experience by writing and the ability to communicate in Italian.

RESULTS

The analysis of narratives led to understanding the PWS social and relational issues concerning diagnosis and current management, PWS daily experiences and social contexts, PWS implications in the working sphere and participants' future perspectives. Narratives demonstrated that PWS management affects relationships and work-life balance and that social stigma remains present.

CONCLUSION

The project represented the first effort to investigate the impact of PWS on illness experience in Italy through NM while considering the perspectives of patients with PWS and their caregivers. The findings indicated that a multiprofessional approach is fundamental to ensure adequate treatment and provided elements for its improvement.

Update on Diabetes Mellitus and Glucose Metabolism Alterations in Prader-Willi Syndrome

PURPOSE OF REVIEW

This review summarizes our current knowledge on type 2 diabetes mellitus (T2DM) and glucose metabolism alterations in Prader-Willi syndrome (PWS), the most common syndromic cause of obesity, and serves as a guide for future research and current best practice.

RECENT FINDINGS

Diabetes occurs in 10-25% of PWS patients, usually in adulthood. Severe obesity is a significant risk factor for developing of T2DM in PWS. Paradoxically, despite severe obesity, a relative hypoinsulinemia, without the expected insulin resistance, is frequently observed in PWS. The majority of PWS subjects with T2DM are asymptomatic and diabetes-related complications are infrequent. Long-term growth hormone therapy does not adversely influence glucose homeostasis in all ages, if weight gain does not occur. Early intervention to prevent obesity and the regular monitoring of glucose levels are recommended in PWS subjects. However, further studies are required to better understand the physiopathological mechanisms of T2DM in these patients.

Relationship between phenotype and genotype of 102 Chinese newborns with Prader-Willi syndrome

High rates of misdiagnosis and delayed intervention in neonatal PWS are leading to poor prognoses. To determine the clinical and image characteristics of newborns with Prader-Willi syndrome (PWS). A total of 102 cases of newborns definitively diagnosed with PWS at the Children's Hospital of Fudan University from 02/2014 to 12/2017 were retrospectively analyzed. We analyzed the modulated voxel-based morphology (VBM) of gray matter in PWS by T2 weighted imaging. Of 102 cases, 75 (73.5%) have paternal deletion of 15q11.2-q13, whereas 27 (26.5%) have maternal uniparental disomy (UPD). Of the 75 deletion cases, 75 (100%) week crying, 71 (94.7%) hypotonia, 70 (93.3%) poor feeding, 46 (61.3%) hypopigmentation, 43 (57.3%) male cryptorchidism, 10 (13.3%) female labia minora, 48 (64%) characteristic facial features. Of 27 UPD cases, 27 (100%) week crying and hypotonia, 25 (92.6%) hypophagia, 20 (74.1%) male cryptorchidism, 1 (3.7%) female labia minora, 19 (70.4%) characteristic facial features, 12 (44.4%) hypopigmentation. The modulated VBM analysis shows that the middle frontal gyrus, orbitofrontal cortex (middle), and inferior frontal gyrus are the most variable brain regions that determine the endo-phenotype difference between the two genotypes. Hypotonia, hypophagia, and maldevelopment of sexual organs are general characteristics of newborns with PWS in Chinese population. In UPD cases, the proportions of premature newborns, elderly parturient women and congenital malformations were higher than for paternal deletion cases. The differences in the gray matter volume of these three regions between the two genotypes may explain the differences in maladaptive behaviors and emotions.

An unusual case of adolescent type 2 diabetes mellitus: Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a complex genetic disorder, characterized by neonatal hypotonia, developmental delay, short stature, childhood obesity, hypogonadism, and characteristic facial features. Here we report a 21-year-old male who presented with uncontrolled glycemic status. He was diagnosed to have diabetes mellitus at the age of 15 with osmotic symptoms - polyuria, polydipsia, and polyphagia. In the early period, after diagnosis, his blood sugars were reasonably controlled with oral hypoglycemic agents. However, a year back, he was switched onto insulin therapy due to secondary OHA failure. On examination, his body mass index was 36 kg/m(2). 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. Hormonal evaluation showed low testosterone and inappropriately normal fluorescence in situ hybridization suggestive of central hypogonadism. With fetal and neonatal hypotonia, delayed developmental milestones, hypogonadism, and early onset diabetes, he fulfilled the clinical criteria for the diagnosis of PWS. Multidisciplinary approach of clinicians together with family and social support are essential to bring out the optimal outcome for such syndromic cases.

Pituitary-Adrenal Axis in Prader Willi Syndrome

PURPOSE

Prader Willi syndrome (PWS) is a rare genetic condition that has concurrent endocrinological insufficiencies. The presence of growth hormone deficiency has been well documented, but adrenal insufficiency (AI) is not widely reported. A review was conducted to investigate its prevalence and relevance in PWS in both adults and children.

METHODOLOGY

A literature review was performed with the search terms "Prader-Willi syndrome" and "adrenal insufficiency".

RESULTS

The review found studies disagree on the prevalence and method of investigation of AI in PWS. Case studies demonstrate that patients with PWS are at risk of premature death, often secondary to respiratory infections. The possibility that this may be the result of the inability to mount an effective cortisol response has been studied, with some evidence confirming AI in PWS patients. Most reports agreed AI is present in PWS, however, Farholt et al. showed no HPA axis dysfunction in adults, suggesting that perhaps it is rare in adults, and children should be the focus of further studies.

CONCLUSION

AI is present in some patients with PWS. Further research is required to ensure optimal treatment can be implemented and to prevent premature deaths related to adrenal insufficiency. Clinicians should have a low threshold for testing the adrenal axis and considering treatment for adrenal insufficiency in PWS patients.

Review of growth hormone therapy in adolescents and young adults with Prader-Willi syndrome

Consensus guidelines from the Growth Hormone Research Society Workshop recommend growth hormone therapy in all children with genetically confirmed Prader-Willi syndrome (PWS) in combination with dietary, lifestyle and environmental interventions. As yet, however, there are limited published data regarding the use of growth hormone therapy in adolescents and young adults with PWS. This review focuses on the advantages and disadvantages of growth hormone therapy in this particular group. The risk of complications, challenges with consent for therapy, the need for contraception in females with PWS and the appropriate monitoring required are all factors which must be carefully considered in this challenging patient group. Transition from paediatric to adult services can be difficult for most adolescents, but especially so for PWS adolescents and should be undertaken under the care of experienced paediatric and adult endocrinologists and a multidisciplinary team approach. Further research is, however, still required in the management of PWS patients during adolescence.

Growth hormone response to standard provocative stimuli and combined tests in very young children with Prader-Willi syndrome

BACKGROUND

In Prader-Willi syndrome (PWS) a reduced growth hormone (GH) response to several stimulators has been documented in many studies, but none have focused on very young children. We evaluated the pattern of GH secretion in very young PWS patients.

PATIENTS AND METHODS

Twenty-seven genetically confirmed PWS children (10 females, aged 0.4-5 years, mean: 2.2 ± 1.4 years) were included. All subjects underwent standard provocative tests (clonidine, CLO; and arginine, ARG) and one combined test [growth hormone-releasing hormone (GHRH) plus pyridostigmine (13 patients) or GHRH plus arginine (14 patients)]. Insulin-like growth factor-1 (IGF-1) levels were also measured.

RESULTS

While standard tests (CLO and ARG) showed low GH peak in 85.2 and 70.4% of the patients, respectively, the combined test was found to be normal in 85.2%. IGF-1 was low in 66.7% of patients. Out of 27 patients, 3 (11%) showed a normal GH peak with both standard tests (group A), 6 (22%) to one of the standard tests (group B) and 18 (67%) presented a low response to both standard tests (group C). Four subjects showed low response to both the combined and standard tests and reduced IGF-1.

CONCLUSION

Our data suggest that very young PWS children seem to have impaired hypothalamic GHRH secretion with a normal GH pituitary reserve.

Prevalence of Prader-Willi syndrome among infants with hypotonia

OBJECTIVE

To investigate the prevalence of Prader-Willi syndrome (PWS) in infants with hypotonia between the ages of 0 and 2 years.

STUDY DESIGN

Karyotyping studies were performed in all infants with hypotonia. The study group was composed of infants with hypotonia for whom the karyotyping was found to be normal. Fluorescence in situ hybridization and methylation analysis were performed simultaneously in the study group. Molecular studies for uniparental disomy were undertaken in the patients without deletions with an abnormal methylation pattern.

RESULTS

Sixty-five infants with hypotonia with a mean age of 8 months were enrolled. A deletion was detected in 6 patients by fluorescence in situ hybridization analysis. Only 1 patient had no deletion but had an abnormal methylation pattern. A maternal uniparental disomy was observed in this patient. PWS was diagnosed in 10.7 % (7/65) of the infants with hypotonia.

CONCLUSION

The prevalence of PWS syndrome is high among infants with hypotonia. PWS should be considered by pediatricians and neonatologists in the differential diagnosis of all newborns with hypotonia. Early diagnosis of PWS is important for the management of these patients.

An obese young man with uncontrolled diabetes and insatiable hunger: Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a rare cause of obesity. With the rising incidence of obesity, clinicians need to be aware of genetic causes of obesity and when to suspect them. A case of PWS, which was diagnosed in adulthood, has been discussed. This case is special because of lack of history of floppiness in infancy and predominance behavioral problems.

Multiple forms of hypogonadism of central, peripheral or combined origin in males with Prader-Willi syndrome

BACKGROUND

Hypogonadism in Prader-Willi syndrome (PWS) is generally attributed to hypothalamic dysfunction or to primary gonadal defect, but pathophysiology is still unclear.

OBJECTIVES

To investigate the aetiology of hypothalamic-pituitary-gonadal axis dysfunction in PWS males.

METHODS

Clinical examination and blood sampling for luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, inhibin B and sexhormone-binding globulin (SHBG) were performed in 34 PWS patients, age 5·1-42·7 years, and in 125 healthy males of same age range. All participants were divided into two groups : < or ≥13·5 years.

RESULTS

Pubertal PWS patients showed an arrest of pubertal development. Patients <13·5 years had normal LH, FSH, testosterone and 7/10 had low inhibin B. Among those ≥13·5 years, 8/24 patients had normal LH and testosterone, high FSH and low inhibin B. 5/24 had low FSH, LH, testosterone and inhibin B; one showed normal LH and FSH despite low testosterone and inhibin B; 4/24 had low testosterone and LH but normal FSH despite low inhibin B; 6/24 showed high FSH, low inhibin B and normal LH despite low testosterone. Compared with controls, patients <13·5 years had lower LH, inhibin B, similar FSH, testosterone, SHBG levels and testicular volume; those ≥13·5 years had smaller testicular volume, near-significantly lower LH, testosterone, SHBG, inhibin B and higher FSH.

CONCLUSION

PWS patients display heterogeneity of hypogonadism: (i) hypogonadotropic hypogonadism of central origin for LH and/or FSH; (ii) early primary testicular dysfunction (Sertoli cells damage); and (iii) a combined hypogonadism (testicular origin for FSH-inhibin B axis and central origin for LH-T axis).

Prader-willi syndrome: clinical aspects

Prader-Willi Syndrome (PWS) is a complex multisystem genetic disorder that shows great variability, with changing clinical features during a patient's life. The syndrome is due to the loss of expression of several genes encoded on the proximal long arm of chromosome 15 (15q11.2-q13). The complex phenotype is most probably caused by a hypothalamic dysfunction that is responsible for hormonal dysfunctions and for absence of the sense of satiety. For this reason a Prader-Willi (PW) child develops hyperphagia during the initial stage of infancy that can lead to obesity and its complications. During infancy many PW child display a range of behavioural problems that become more noticeable in adolescence and adulthood and interfere mostly with quality of life. Early diagnosis of PWS is important for effective long-term management, and a precocious multidisciplinary approach is fundamental to improve quality of life, prevent complications, and prolong life expectancy.