Clinical evidence of intrauterine disturbance in Prader-Willi syndrome, a genetically imprinted neurodevelopmental disorder

Chromosomal Microarray in Children Born Small for Gestational Age - Single Center Experience

The association between small for gestational age birth and chromosomal abnormalities identified through karyotyping is well-established. Notably, advancements in cytogenetic techniques have shifted from routine karyotyping to the recommended use of microarray technology. This transition allows higher resolution and the detection of sub-microscopic copy number variants (CNVs). Our study included 49 patients born small for gestational age, 27 males and 22 females. Clinical data were gathered from reports by clinical genetic specialists, and a questionnaire was included in the referral list to our laboratory. All participants were of pediatric age, ranging from neonatal to 12 years old. Chromosomal microarray testing was conducted by the Agilent SurePrint G3 Human CGH Microarray 8×60K. The application of molecular karyotyping yielded clinically significant results in 16 cases (32.65%), which included 13 deletions and 6 duplications. Three patients presented with two clinically significant CNVs (csCNVs). In ten cases, we identified recurrent microdeletion or microduplication syndromes well-documented in the literature: Williams syndrome as the most commonly identified (three patients), and others like Koolen de Vries, Prader-Willi, Miller-Dieker, Dryer, DiGeorge syndrome, 7q11.23 microduplication, 16p13.11 microdeletion, and 1q21.1 microdeletion syndrome. Six patients had rare non-recurrent pathological CNVs. There was no statistically significant difference between patients with csCNVs and those without regarding the presence of intellectual disabilities, central nervous system, cardiac or skeletal malformations. Chromosomal microarray proves to be a useful diagnostic tool in the etiology diagnosis of children born small for gestational age.

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.

Recommendations for the diagnosis and management of childhood Prader-Willi syndrome in China

Prader-Willi syndrome (PWS) is a complex and multisystem neurobehavioral disease, which is caused by the lack of expression of paternally inherited imprinted genes on chromosome15q11.2-q13.1. The clinical manifestations of PWS vary with age. It is characterized by severe hypotonia with poor suck and feeding difficulties in the early infancy, followed by overeating in late infancy or early childhood and progressive development of morbid obesity unless the diet is externally controlled. Compared to Western PWS patients, Chinese patients have a higher ratio of deletion type. Although some rare disease networks, including PWS Cooperation Group of Rare Diseases Branch of Chinese Pediatric Society, Zhejiang Expert Group for PWS, were established recently, misdiagnosis, missed diagnosis and inappropriate intervention were usually noted in China. Therefore, there is an urgent need for an integrated multidisciplinary approach to facilitate early diagnosis and optimize management to improve quality of life, prevent complications, and prolong life expectancy. Our purpose is to evaluate the current literature and evidences on diagnosis and management of PWS in order to provide evidence-based guidelines for this disease, specially from China.

Prenatal and Neonatal Characteristics of Children with Prader-Willi Syndrome

Objective: Prader-Willi syndrome (PWS) is a rare genetic syndrome with a wide spectrum of clinical features in early life. Late diagnoses are still present. We characterized the perinatal and neonatal features of PWS, compared them with those of healthy newborns and assessed the prenatal and neonatal differences between the genetic subtypes. Design: A cohort study in children with PWS. The prevalence of variables was compared with healthy infants (PLUTO cohort) and to population statistics from literature. Patients: 244 infants with PWS and 365 healthy infants. Measurements: Data on prenatal and neonatal variables in both cohorts. Population statistics were collected through an extensive literature search. Results: A higher prevalence of maternal age >35 years was found in PWS compared to healthy infants and population statistics, and the highest maternal age was found in the mUPD group. Higher prevalence of polyhydramnios, caesarean section, labour induction and breech presentation, and lower birth weight SDS was found in PWS compared to healthy infants. High prevalences of decreased fetal movements (78.5%), hypotonia (100%), cryptorchism (95.9%) and poor sucking/tube feeding (93.9%) were found in PWS. Conclusions: This study presents an overview of prenatal and neonatal variables in infants with PWS compared to healthy infants. Our findings may increase clinical awareness of the early perinatal signs of PWS by obstetricians, neonatologists and all those involved in infant care, enabling early diagnosis and start of multidisciplinary treatment.

Prader-Willi syndrome: Hormone therapies

Prader-Willi syndrome (PWS) is a rare genetic neurodevelopmental disorder linked to the lack of expression of specific maternally imprinted genes located in the chromosomal region 15q11-q13. Impaired hypothalamic development and function explain most of the phenotype that is characterized by a specific trajectory from anorexia at birth to excessive weight gain at later ages, which is accompanied by hyperphagia and early severe obesity, as well as by other hormonal deficiencies, behavioral deficits, and dysautonomia. In almost all patients, their endocrine dysfunction involves growth hormone deficiency and hypogonadism, which originate from a combination of both peripheral and hypothalamic origin, central hypothyroidism in 40%, precocious adrenarche in 30% of the cases, and in rare cases, also adrenocorticotropin deficiency and precocious puberty. In addition, the oxytocin (OXT) and ghrelin systems are impaired in most patients and involved in a poor suckling response at birth, and hyperphagia with food addiction, poor social skills, and emotional dysregulation. Current hormonal replacement treatments are the same as used in classical hormonal deficiencies, and recombinant human GH treatment is registered since 2000 and has dramatically changed the phenotype of these children. OXT and OXT analogue treatments are currently investigated as well as new molecules targeting the ghrelin system. The severe condition of PWS can be seen as a model to improve the fine description and treatments of hypothalamic dysfunction.

Evaluation of chromosomal abnormalities and copy number variations in late trimester pregnancy using cordocentesis

Because the numbers of detected fetal abnormalities increase as gestation progresses, we evaluated the safety and efficacy of cordocentesis for single nucleotide polymorphism (SNP) analysis tests in 754 women during third trimester pregnancy. Conventional karyotyping was performed on all fetuses, and Affymetrix CytoScan HD was used for SNP-array testing. In addition to the 24 cases with chromosomal abnormalities detected with conventional karyotyping analysis, the SNP-array test identified 56 (7.4%) cases with normal karyotypes but abnormal copy number variations (CNVs). Of those, 24 were pathogenic CNVs and 32 were of uncertain clinical significance. In 742 of the cases, there were abnormal sonographic findings, and cytogenetic abnormalities were detected in 76 cases (10.2%). The largest number of abnormalities involved multiple malformations (21.7%), followed by defects in the lymphatics or effusion (19.0%) or urogenital system (15.3%). The use of SNP-array test fully complemented chromosome karyotype analysis after late cordocentesis. It also improved the detection rate for fetal chromosomal abnormalities and was effective for preventing and controlling the occurrence of birth defects.

Recognizing the unique prenatal phenotype of Prader-Willi Syndrome (PWS) indicates the need for a diagnostic methylation test

OBJECTIVES

Prader-Willi syndrome (PWS) is a neurogenetic disorder characterized by mental retardation, morbid obesity, and endocrine and behavior disorders. We previously showed in a small group of patients that PWS may have a unique prenatal phenotype. We aimed to characterize clinical and ultrasonic features in a larger series of pregnancies with a PWS fetus.

METHODS

We retrospectively interviewed all mothers of children with PWS followed in the Israel national multidisciplinary PWS clinic. We compared details of the PWS pregnancy with the pregnancies of healthy siblings and with data from the general population. Medical records including ultrasound reports, obstetric records, and genetic results were analyzed.

RESULTS

Distinct prenatal features of PWS pregnancies included abnormal fetal growth [fetal growth restriction (FGR) (37.3%), increased head to abdominal circumference ratio (44.8%), decreased abdominal circumference (49.2%)], markedly decreased fetal movements (DFM) (80.4%), and polyhydramnios (42.0%) (P < 0.001 for all). The combination of abnormal growth accompanied by polyhydramnios or DFM was highly suggestive for PWS.

CONCLUSIONS

Recognition of the unique PWS phenotype should alert obstetricians to consider the possibility of PWS, perform the diagnostic methylation test, provide appropriate counseling, and plan optimal management of the affected pregnancy.

Perinatal features of Prader-Willi syndrome: a Chinese cohort of 134 patients

Background

Prader-Willi syndrome (PWS) is a rare and complex genetic disorder caused by lacking expression of imprinted genes on the paternally derived chromosome 15q11-q13 region. This study aimed to characterize the perinatal features of 134 Chinese individuals with PWS.

Methods

This study included the patients of a PWS registry in China. Anonymous data of 134 patients were abstracted. Perinatal and neonatal presentations were analyzed, and compared between the two PWS genetic subtypes. We also compared the perinatal features of PWS patients with the general population and other previous reported large cohorts from France, UK and USA.

Results

This study included 134 patients with PWS (115 patients with 15q11-q13 deletion and 19 with maternal uniparental disomy). Higher mean maternal age was found in this cohort (30.5 vs. 26.7), particularly in the maternal uniparental disomy (UPD) group (36.0 vs. 26.7) comparing with the general population. 88.6% of mothers reported a decrease of fetal movements. 42.5 and 18.7% of mothers had polyhydramnios and oligohydramnios during pregnancy, respectively. 82.8% of the patients were born by caesarean section. 32.1% of neonates had birth asphyxia, 98.5% had hypotonia and 97.8% had weak cry or even no cry at neonatal period. Feeding difficulty existed in 99.3% of the infants, 94.8% of whom had failure to thrive. 69.4% of the infants ever used feeding tube during hospitalization, however, 97.8% of them discontinued tube feeding after discharge. Maternal age and pre-pregnancy weight were significantly higher in the UPD group (both P < 0.05).

Conclusions

Differential diagnosis of PWS should be highlighted if infants having following perinatal factors including polyhydramnios, decreased intrauterine fetal movements, caesarean section, low birth weight, feeding difficulty, hypotonia and failure to thrive. Higher maternal age may be a risk factor of PWS, especially for UPD. Further studies are needed for elucidating the mechanism of PWS.

Anthropometric characteristics of newborns with Prader-Willi syndrome

This is a retrospective multicenter nationwide Italian study collecting neonatal anthropometric data of Caucasian subjects with Prader-Willi syndrome (PWS) born from 1988 to 2018. The aim of the study is to provide percentile charts for weight and length of singletons with PWS born between 36 and 42 gestational weeks. We collected the birth weight and birth length of 252 male and 244 female singleton live born infants with both parents of Italian origin and PWS genetically confirmed. Percentile smoothed curves of birth weight and length for gestational age were built through Cole's lambda, mu, sigma method. The data were compared to normal Italian standards. Newborns with PWS showed a lower mean birth weight, by 1/2 kg, and a shorter mean birth length, by 1 cm, than healthy neonates. Females with a 15q11-13 deletion were shorter than those with maternal uniparental maternal disomy of chromosome 15 (p < .0001). The present growth curves may be useful as further traits in supporting a suspicion of PWS in a newborn. Because impaired prenatal growth increases risk of health problems later in life, having neonatal anthropometric standards could be helpful to evaluate possible correlations between the presence or absence of small gestational age and some clinical and metabolic aspects of PWS.

Prader-Willi syndrome: A model for understanding the ghrelin system

Subsequent to the discovery of ghrelin as the endogenous ligand of growth hormone secretagogue receptor 1a, this unique gut peptide has been found to exert numerous physiological effects, such as appetite stimulation and lipid accumulation via the central regulating mechanisms in the hypothalamus, stimulation of gastric motility, regulation of glucose metabolism and brown fat thermogenesis, and modulation of stress, anxiety, taste sensation, reward-seeking behaviour and the sleep/wake cycle. Prader-Willi syndrome (PWS) has been described as a unique pathological state characterised by severe obesity and high circulating levels of ghrelin. It was hypothesised that hyperghrelinaemia would explain at least a part of the feeding behaviour and body composition of PWS patients, who are characterised by hyperphagia, an obsession with food and food-seeking, and increased adiposity. Initially, the link between hyperghrelinaemia and growth hormone deficiency, which is observed in 90% of the children with PWS, was not fully understood. Over the years, however, the increasing knowledge on ghrelin, PWS features and the natural history of the disease has led to a more comprehensive description of the abnormal ghrelin system and its role in the pathophysiology of this rare and complex neurodevelopmental genetic disease. In the present study, we (a) present the current view of PWS; (b) explain its natural history, including recent data on the ghrelin system in PWS patients; and (c) discuss the therapeutic approach of modulating the ghrelin system in these patients and the first promising results.

Comparison of perinatal factors in deletion versus uniparental disomy in Prader-Willi syndrome

Prader-Willi syndrome (PWS) is caused by a deficiency of imprinted genes in the 15q11-q13 region and is characterized by prenatal onset of hypotonia, poor feeding, childhood-onset obesity, hyperphagia, short stature, facial dysmorphism, intellectual disability, and behavioral problems. We studied perinatal factors in a cohort of 64 people with PWS resulting from paternal deletion of 15q11-q13 and maternal uniparental disomy (UPD) for chromosome 15. We recruited 34 individuals with deletion and 30 with UPD. We compared the frequency of multiple prenatal and neonatal factors with the general population as well as between the two genetic subtypes. Of the 64 individuals with PWS, fetal movements were decreased in 82.8%, 31.7% were born prematurely, 42.1% by Cesarean section, and 35.9% required oxytocin induction. Apgar scores were low in 34.6%, 96.8% had feeding difficulty, 50% needed tube feeding, and 6.2% subsequently had gastrostomy tube placement. On comparing findings in the deletion versus the UPD groups, we did not find many significant differences. We, however, found a higher maternal age, and also later age at diagnosis in the UPD versus the deletion group. PWS subjects have higher rates of perinatal complications, especially Cesarean section rate, hypotonia, and low Apgar scores compared to the general population. We did not find many differences between the genetic subtypes, except for later age of diagnosis of the UPD 15 group suggesting a milder phenotype. We also found that the mothers in the UPD were older, supporting the hypothesis that UPD results from nondisjunction associated trisomy rescue.

Multicentre study of maternal and neonatal outcomes in individuals with Prader-Willi syndrome

INTRODUCTION

Prader-Willi syndrome (PWS) is a complex genetic disorder associated with three different genetic subtypes: deletion of the paternal copy of 15q11-q13, maternal UPD for chromosome 15 and imprinting defect. Patients are typically diagnosed because of neonatal hypotonia, dysmorphism and feeding difficulties; however, data on the prenatal features of PWS are limited.

OBJECTIVE

The aim of the study was to identify and compare frequencies of prenatal and neonatal clinical features of PWS among the three genetic subtypes.

METHODS

Data from 355 patients with PWS from the Rare Diseases Clinical Research Network PWS registry were used to analyse multiple maternal and neonatal factors collected during an 8-year multisite study.

RESULTS

Among our cohort of 355 patients with PWS (61% deletion, 36% UPD and 3% imprinting defect) 54% were born by caesarean section, 26% were born prematurely and 34% with a low birth weight (frequencies 32%, 9.6% and 8.1%, respectively, in the general population). Fetal movements were reported as decreased in 72%. All babies were hypotonic, and 99% had feeding difficulties. Low Apgar scores (<7) were noted in 17.7% and 5.6% of patients, respectively, compared with 1% and 1.4%, respectively, in the general population. Maternal age and pre-pregnancy weight were significantly higher in the UPD group (p=0.01 and <0.001, respectively).

CONCLUSION

We found a higher rate of perinatal complications in PWS syndrome compared with the general population. No significant differences in the genetic subtypes were noted except for a higher maternal age and pre-pregnancy weight in the UPD subgroup.

Neonatal Features of the Prader-Willi Syndrome; The Case for Making the Diagnosis During the First Week of Life

OBJECTIVE

Early diagnosis is of proven benefit in Prader-Willi syndrome (PWS). We therefore examined key perinatal features to aid early recognition.

METHODS

Data were collected from case records of subjects attending a multi-disciplinary clinic and from a retrospective birth questionnaire.

RESULTS

Ninety patients (54 male-36 female) were seen between 1991-2015, most with paternal deletion (n=56) or maternal isodisomy (n=26). Features included cryptorchidism in 94% males, preterm birth (26%), birthweight <2500 g (24%), polyhydramnios (23%), breech presentation (23%) and need for nasogastric feeding (83%). Reduced fetal movements (FM) were reported in 82.5% patients compared with 4% healthy siblings. Of 35 children born since 1999, 23 were diagnosed clinically within 28 days while diagnosis in 12 was >28 days: 1-12 months in seven; and 3.75-10.5 years in five. Typical PWS features in these 12 infants included hypotonia (100%), feeding difficulties (75%), cryptorchidism (83% males) and reduced FM (66%). Causes other than PWS including neuromuscular disease were considered in nine patients.

CONCLUSION

Neonatal hypotonia, reduced FM, feeding difficulties and cryptorchidism should immediately suggest PWS, yet late diagnosis continues in some cases. Awareness of the typical features of PWS in newborn units is required to allow prompt detection even in the presence of confounding factors such as prematurity.

Application of chromosomal microarray to investigate genetic causes of isolated fetal growth restriction

Background

Application of chromosomal microarray analysis (CMA) to investigate the genetic characteristics of fetal growth restriction (FGR) without ultrasonic structural anomalies at 18–32 weeks.

Methods

This study includes singleton fetuses with the estimated fetal weight (EFW) using the formula of Hadlock C below the 10th percentile for gestational age. FGRs without structural anomalies were selected, and the ones at high risk of noninvasive prenatal testing for trisomy 13, 18 and 21 would be excluded. The cases were divided into two groups: early-onset group (< 24^+ 0 weeks) and late-onset group (24–33 weeks). All patients were offered invasive prenatal testing with CMA and karyotype analysis.

Results

CMA detected 10 pathogenic copy number variants and 2 variant of uncertain significance case. CMA has a 5.5% (7/127) incremental yield of pathogenic chromosomal abnormalities over karyotyping. The positive detected rate was 9.6% (5/52) in early-onset group and 9.3% (7/75) in late-onset group respectively.

Conclusions

When FGR without structural anomaly is diagnosed before 33 weeks, an invasive prenatal procedure is strongly recommended. CMA can identify a 5.5% (7/127) incremental detection rate of pathogenic chromosomal abnormalities, which would impact clinical management for FGR.

Early diagnosis and care is achieved but should be improved in infants with Prader-Willi syndrome

Background

PWS is a severe neurodevelopmental genetic disorder now usually diagnosed in the neonatal period from hypotonia and feeding difficulties. Our study analyzed the birth incidence and care of infants with early diagnosis.

Methods

Data were collected on 61 infants with a molecular diagnosis of PWS born in 2012 and 2013 in France.

Results

Thirty-eight infants with PWS were born in 2013. The median age at diagnosis was 18 days. Birth incidence calculated for 2013 was 1/21,000 births. No case was diagnosed prenatally, despite 9 amniocenteses, including 4 for polyhydramnios. Five infants had delayed diagnosis, after 3 months of life. For 2 of them, the diagnosis was not suspected at birth and for 3, FISH analysis in the neonatal period was normal, with no further molecular studies. Ninety-three percent of the neonates were hospitalized, and 84% needed nasogastric tube feeding for a median of 38 days. Swallowing assessment was performed for 45%, at a median age of 10 days. Physiotherapy was started for 76% during hospitalization. Eighty percent of those diagnosed within the first 3 months were seen by a pediatric endocrinologist within the first week of life.

Conclusion

Our study is the first to assess the birth incidence of PWS in France, at 1/21,000 births. Some prenatal or neonatal cases remain undiagnosed because of unrecognized clinical signs and the inappropriate choice of the initial molecular test. We also underscore the need to optimize neonatal care of infants with PWS.

Low dose growth hormone treatment in infants and toddlers with Prader-Willi syndrome is comparable to higher dosage regimens

OBJECTIVE

Evaluate benefit and risk of low dose growth hormone treatment (GHT, 4.5mg/m²/week) in very young children with Prader-Willi Syndrome (PWS).

DESIGN

Prospective longitudinal clinical intervention.

METHODS

We evaluated 31 infants (aged 2-12months) and 42 toddlers (13-24months) from the PWS-OZGROW database for height, weight and BMI using the World Health Organization standard deviation scores (SDS_WHO) and PWS specific BMI (SDS_PWS), bone age, insulin-like growth factor 1 (IGF-I) levels and adverse events over 3years of GHT.

RESULTS

At commencement of GHT infants had a lower BMI SDS_WHO (-0.88 vs 0.40) than toddlers, while toddlers had a lower height SDS_WHO (-1.44 vs -2.09) (both P<0.05). All increased height SDS_WHO (2year delta height infants +1.26 SDS, toddlers+1.21 SDS), but infants normalised height sooner, achieving a height SDS of -0.56 within 1year, while toddlers achieved a height SDS of -0.88 in two years. BMI SDS_WHO increased, while BMI SDS_PWS decreased (both P<0.0001) and remained negative. The GHT response did not differ with gestation (preterm 23%) or genetic subtype (deletion vs maternal uniparental disomy). Bone age advancement paralleled chronological age. All children had low serum IGF-I at baseline which increased, but remained within the age-based reference range during GHT (for 81% in first year). Four children had spinal curvature at baseline; two improved, two progressed to a brace and two developed an abnormal curve over the observation period. Mild to severe central and/or obstructive sleep apnoea were observed in 40% of children prior to GHT initiation; 11% commenced GHT on positive airway pressure (PAP), oxygen or both. Eight children ceased GHT due to onset or worsening of sleep apnoea: 2 infants in the first few months and 6 children after 6-24months. Seven resumed GHT usually after adjusting PAP but five had adenotonsillectomy. One child ceased GHT temporarily due to respiratory illness. No other adverse events were reported. Two children substantially improved their breathing shortly after GHT initiation.

CONCLUSION

Initiation of GHT in infants with 4.5mg/m²/week was beneficial and comparable in terms of auxological response to a dose of 7mg/m²/week. Regular monitoring pre and post GH initiation assisted in early detection of adverse events. IGF-I levels increased with the lower dose but not excessively, which may lower potential long-term risks.

Applying Precision Public Health to Prevent Preterm Birth

Preterm birth (PTB) is one of the major health-care challenges of our time. Being born too early is associated with major risks to the child with potential for serious consequences in terms of life-long disability and health-care costs. Discovering how to prevent PTB needs to be one of our greatest priorities. Recent advances have provided hope that a percentage of cases known to be related to risk factors may be amenable to prevention; but the majority of cases remain of unknown cause, and there is little chance of prevention. Applying the principle of precision public health may offer opportunities previously unavailable. Presented in this article are ideas that may improve our abilities in the fields of studying the effects of migration and of populations in transition, public health programs, tobacco control, routine measurement of length of the cervix in mid-pregnancy by ultrasound imaging, prevention of non-medically indicated late PTB, identification of pregnant women for whom treatment of vaginal infection may be of benefit, and screening by genetics and other “omics.” Opening new research in these fields, and viewing these clinical problems through a prism of precision public health, may produce benefits that will affect the lives of large numbers of people.

Medical, psychological and social features in a large cohort of adults with Prader-Willi syndrome: experience from a dedicated centre in France

BACKGROUND

Prader-Willi syndrome (PWS) is a developmental genetic disorder characterised by a variable expression of medical, cognitive and behavioural symptoms. In adulthood, the prevalence and severity of these symptoms determine the quality of life of the affected persons. Because of their rare disease condition, data on health and social problems in adults with PWS are scarce. In this research, we present medical, psychological and social features of a large cohort of adults admitted to a specialised PWS centre in France and analyse the differences according to genotype, gender and age.

METHODS

Data from 154 patients (68 men/86 women), with a median age of 27 years (range 16-54), were collected during their stay in our centre. Clinical histories were completed using information from parents or main caregivers, and the same medical team performed the diagnosis of different clinical conditions. Statistical analyses were performed to determine the influence of factors such as genotype, age or gender.

RESULTS

Paternal deletion genotype was the most frequent (65%) at all ages. Most patients had mild or moderate intellectual disability (87%). Only 30% had studied beyond primary school and 70% were in some special educational or working programme. Most of them lived in the family home (57%). The most prevalent somatic comorbidities were scoliosis (78%), respiratory problems (75%), dermatological lesions (50%), hyperlipidaemia (35%), hypothyroidism (26%), Type 2 diabetes mellitus (25%) and lymph oedema (22%). Some form of psychotropic treatment was prescribed in 58% of subjects, and sex hormones in 43%. Patients with deletion had a higher body mass index (44 vs. 38.9 kg/m(2)) and displayed higher frequency of sleep apnoeas. Non-deletion patients received insulin treatment (19% vs. 4%) and antipsychotic treatment (54.8% vs. 32.7%) more frequently. No difference was observed in the prevalence of Type 2 diabetes between the two genotype groups. Patients >27 years of age had a higher rate of comorbidities (Type 2 diabetes, hypertension, respiratory problems and lymph oedema). Gender differences were minor.

CONCLUSIONS

Adult patients with PWS showed high prevalence of comorbid health problems that need to be monitored for early treatment. Some of them are influenced by genotype and age. Another salient problem concerns the lack of adapted structures for better social integration. Further data about the real life and health conditions of adults with PWS are necessary to further our knowledge of the natural history of the disease and to design appropriate care strategies.

A population-based profile of 160 Australians with Prader-Willi syndrome: trends in diagnosis, birth prevalence and birth characteristics

Perceived temporal trends in recognition and diagnosis of Prader-Willi syndrome served as the rationale for an updated epidemiological profile of individuals with this syndrome. Data from the Victorian Prader-Willi Syndrome Register were used to explore birth prevalence, birth characteristics, timing of diagnosis, and molecular mechanism, and to identify trends over time. Maternal age, birth gestation, small for gestational age, and sex were compared across molecular mechanisms. Between 1951 and 2012 there were 160 individuals with Prader-Willi syndrome, known to the Victorian Prader-Willi Syndrome Register, who were born in the Australian state of Victoria. The birth prevalence for individuals with a molecular diagnosis of Prader-Willi syndrome was estimated to be 1:15,830 for 2003-2012. Compared to 1973-1981, the decade 2003-2012 saw an increase in the rate of molecular diagnosis from 58% to 96%, more complete identification of the molecular mechanism (42% vs. 83%), earlier molecular diagnosis (1.3 years vs. 8.6 weeks), and a rise in the relative proportion of maternal uniparental disomy from 0% to 45%. One quarter of infants was born preterm and 53% were small for gestational age. This study confirms a temporal change in diagnostic patterns, suggests a greater relative contribution of maternal uniparental disomy as a molecular mechanism, provides a more robust estimate of birth prevalence and provides evidence of in utero growth restriction for this group. These findings have important clinical and health service delivery implications and pave the way for further research in Prader-Willi syndrome.

Eating behavior, prenatal and postnatal growth in Angelman syndrome

The objectives of the present study were to investigate eating behavior and growth parameters in Angelman syndrome. We included 39 patients with Angelman syndrome. Twelve cases had a larger Class I deletion, eighteen had a smaller Class II deletion, whereas paternal uniparental disomy (pUPD) or a verified UBE3A mutation were present in five and four cases, respectively. Eating behavior was assessed by a questionnaire. Anthropometric measures were obtained from medical records and compared to Danish reference data. Children with pUPD had significantly larger birth weight and birth length than children carrying a deletion or a UBE3A mutation. We found no difference in birth weight or length in children with Class I or Class II deletions. When maternal birth weight and/or birth weight of siblings were taken into consideration, children with Class I deletion had a lower weight at birth than expected, and the weight continued to be reduced during the investigated initial five years of life. In contrast, children with pUPD showed hyperphagic behavior and their weight increased significantly after the age of two years. Accordingly, their body mass index was significantly increased as compared to children with a deletion. At birth, one child showed microcephaly. At five years of age, microcephaly was observed in half of the deletion cases, but in none of the cases with a UBE3A mutation or pUPD. The apparently normal cranial growth in the UBE3A and pUPD patients should however be regarded as the result of a generally increased growth. Eating behavior, pre- and postnatal growth in children with Angelman syndrome depends on genotype.

Prader-Willi syndrome can be diagnosed prenatally

The aim of this study was to characterize the fetal phenotype of a cohort of individuals with confirmed diagnoses of Prader-Willi syndrome (PWS), a severe multi-system genetic disorder, diagnosed by a specific methylation test. We interviewed mothers of 106 individuals with PWS to obtain information about the pregnancy of their affected child. For 47 pregnancies of children younger than 10 years, we also reviewed the obstetric ultrasound and detailed obstetric history from medical records. We compared the PWS pregnancies with those of the sibling closest in age and with the general population. McNemars, Chi-square and Fisher exact tests were used for statistical analyses. Decreased fetal movements, small for gestational age (SGA), asymmetrical intrauterine growth (increased head/abdomen circumferences ratio) and polyhydramnios were found in 88%, 65%, 43%, and 34%, respectively (P < 0.001 vs. siblings and P < 0.0001 vs. the general population for all measurements). No severe morphological abnormalities were found. A combination of 2, 3, and 4 abnormalities was found in 27%, 29%, and 24% of pregnancies, respectively. Fourteen out of 15 umbilical artery Doppler studies were within the normal range (93%). The rare combination of asymmetrical intrauterine growth and polyhydramnios was found in 34% of PWS pregnancies (P < 0.0001 vs. the general population). Prenatal genetic screening for PWS by methylation testing is indicated when any combination of polyhydramnios, SGA or asymmetric intrauterine growth, with normal Doppler studies is present, particularly when asymmetrical intrauterine growth and polyhydramnios coexist.

Premature birth with complicated perinatal course delaying diagnosis of prader-willi syndrome

Prader-Willi syndrome in the newborn is essentially characterized by marked hypotonia, feeding difficulties, hypogonadism, and possible characteristic facial features. However, diagnosis at this age may be particularly difficult, and dysmorphic features may be subtle or absent. Prematurity can furthermore delay clinical features recognition and typical complications due to preterm birth may contribute to divert the diagnosis. We describe a preterm baby with a complicated perinatal course later diagnosed as PWS.

A short clinical overview of Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a multifaceted developmental disorder most commonly associated with extreme hyperphagia and life-threatening obesity. PWS is a genetic disorder of imprinting with almost all cases occurring spontaneously. Behavioural and imaging studies have shown that obesity in PWS arises from overeating driven by a faulty satiety mechanism which manifests as an almost permanent state similar to starvation. With no available treatments, management of the eating behaviour is the only option and has two main strategies: restrict access to food and distract thoughts from food. In this mini review, which we have aimed at clinicians, we outline the main aspects of PWS including genetics, development of the eating behaviour and best practice approaches to management.

Neurobehavioral phenotype in Prader-Willi syndrome

The focus of this article is on the lifetime development of people with Prader-Willi syndrome (PWS) and specifically on the neurobehavioral phenotype. We consider studies of this aspect of the phenotype (the "behavioral phenotype" of the syndrome) that have confirmed that there are specific behaviors and psychiatric disorders, the propensities to which are increased in those with PWS, and cannot be accounted for by other variables such as IQ or adaptive behavior. Beginning with a description of what is observed in people with PWS, we review the evolving PWS phenotype and consider how some aspects of the phenotype might be best explained, and how this complex phenotype may relate to the equally complex genotype. We then consider in more detail some of the neurobehavioral aspects of the phenotype listed above that raise the greatest management problems for parents and carers.

Perinatal dyskinesia as a presenting feature in Prader Willi syndrome

Prader Willi Syndrome (PWS) is a complex genetic disorder. Infants present with hypotonia and feeding difficulties, usually without respiratory symptoms, but with distinctive facial features. Early neonatal diagnosis can however be difficult in children with only subtle distinctive appearances or with atypical clinical signs, leading to a significant delay in the diagnosis. To highlight the diagnostic difficulties we reviewed our experience of infants with PWS referred to our tertiary centre. We describe 14 patients, 10 of whom presented in the neonatal period. All had axial hypotonia, and poor feeding. Twelve had a paucity of movement, 11 had distinctive features and 10 had a reduced level of alertness in the neonatal period. In addition to these typical features, four patients had prominent limb dyskinesia, which has only been reported once before in infants with PWS. We draw attention to this relatively common but poorly acknowledged sign that can be seen at presentation of PWS.

Relationship between the IQ of people with Prader-Willi syndrome and that of their siblings: evidence for imprinted gene effects

BACKGROUND

Genetic disorders occasionally provide the means to uncover potential mechanisms linking gene expression and physical or cognitive characteristics or behaviour. Prader-Willi syndrome (PWS) is one such genetic disorder in which differences between the two main genetic subtypes have been documented (e.g. higher verbal IQ in one vs. higher performance IQ in the other; slower than normal reaction time in one vs. normal in the other). In a population study of PWS, the IQ distribution of people with PWS was approximately normal. This raises the question of whether this distribution arose from a systematic effect of PWS on IQ (hypothesis 1) or whether it was the fortuitous result of random effects (hypothesis 2).

METHOD

The correlation between PWS and sibling IQ was determined in order to discriminate between the two hypotheses. In the first case we would expect the correlation to be similar to that found in the general population (0.5); in the second case it would be zero.

RESULTS

It was found that the overall PWS-sibling IQ correlation was 0.3 but that the two main genetic subtypes of PWS differed in their familial IQ relationships. As expected, the IQs of normal siblings correlated 0.5, and this was also the case with one genetic subtype of PWS (uniparental disomy) and their siblings, while the other subtype IQ correlated -0.07 with sibling IQ.

CONCLUSIONS

This is a potentially powerful result that gives another clue to the role of genes on chromosome 15 in the determination of IQ. It is another systematic difference between the genetic subtypes of PWS, which needs an explanation in terms of the very small genetic differences between them.

Cross-cultural comparisons of obesity and growth in Prader-Willi syndrome

Introduction The present study reports cross-cultural comparisons of body mass index (BMI) and growth in Prader-Willi syndrome, a neurodevelopmental disorder associated with obesity, growth restriction and mild learning disability. Our objectives were to: (1) compare rates of obesity in adults with Prader-Willi syndrome (PWS) in France, with data available from Belgium, the UK and the USA; (2) compare growth of French children with PWS with their counterparts in Germany and the USA; and (3) evaluate the contribution of genetic, medical and social parameters to obesity outcome in French children and adults with PWS. Method (1) Cross-sectional comparison of BMI of 40 French adults, 38 Belgian adults, 46 British adults and 292 North American adults; (2) Construction of growth curves for French children aged 2-20 years from longitudinal data for 150 individuals with PWS, and comparison with published growth curves from Germany and the USA; and (3) Longitudinal regression analysis of 141 French children and adults to determine the factors contributing to obesity outcome. Results A total of 82.5% French adults with PWS have BMI > 30 compared with 65.8% in Belgium (n.s.), 58.2% in the USA (P < 0.005), and 54.3% in the UK (P < 0.01). Higher rates of obesity in females vs. males were found in the USA sample (P < 0.001) but not in the other samples. In contrast to adults, growth curves for French children with PWS show similar rates of growth compared with children with PWS in Germany and the USA. The principal determining factors of BMI status in the French PWS population are age (P < 0.0001), cohort (born within the last 15 years vs. born over 15 years ago, P < 0.0002) and growth hormone replacement therapy (P < 0.0002). Significant subsidiary effects include domestic situation (P < 0.0001), genetic diagnosis (P < 0.0001) and age of diagnosis (P < 0.0001). Conclusions French adults with PWS have significantly higher rates of obesity than adults in the UK and the USA, but growth in French children with PWS is similar to the USA and Germany. Clinical management has a greater impact on obesity outcome in PWS than cultural factors.

Pre-, peri- and postnatal complications in Prader-Willi syndrome in a UK sample

BACKGROUND

Few studies describe in detail the pregnancy and early development of infants with Prader-Willi syndrome (PWS). However, variations at these early stages may partially account for differences in the later phenotype. A recent paper described an abnormally high number of problems in pregnancy and early infancy in a large sample of people with PWS but this sample was not homogeneous with respect to age and potentially liable to cohort effects.

AIMS

To describe the early development of infants with PWS, younger and more homogeneous for age, and to investigate whether such high rates of perinatal problems are still present despite medical advances and whether there are differences according to the genetic subtypes.

STUDY DESIGN

Using a structured interview, data were collected from mothers and from relevant GP and hospital records.

SUBJECTS

Forty-six babies with PWS, born in a six-year period 2000-2006, and their mothers.

OUTCOME MEASURES

Problems arising during pregnancy, the birth process and the neonatal period and the birth characteristics of the babies.

RESULTS

An abnormally high number of problems associated with the early developmental period similar to those previously reported were observed. The only significant difference between the genetic subtypes was that mother's age was positively correlated with birth weight for UPD (and negatively correlated for deletion subtypes).

CONCLUSIONS

High rates of, and variability in, the nature and severity of problems arising during early development have been confirmed. To establish whether variability in the later phenotype is influenced by such differences requires a longitudinal study.