Testicular failure in boys with Prader-Willi syndrome: longitudinal studies of reproductive hormones

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.

Premature adrenarche in Prader-Willi syndrome is associated with accelerated pre-pubertal growth and advanced bone age

OBJECTIVES

Prader-Willi syndrome (PWS) is characterized by obesity, growth hormone deficiency, hypogonadism, and a high prevalence of premature adrenarche despite reported hypothalamic-pituitary-adrenal axis dysfunction. While idiopathic premature adrenarche is associated with accelerated pre-pubertal growth and advanced bone age, the consequences of elevated adrenal androgens on growth and bone maturation in PWS remain unknown. This study therefore sought to describe age-related changes in dehydroepiandrosterone sulfate (DHEAS) and their effects on growth and bone maturation in PWS.

METHODS

This retrospective observational study included 62 children with PWS. Simple and multiple regression models were constructed to relate age and BMI-SDS with DHEAS levels. Height velocity was compared to age and sex-based norms with t-tests and two-way ANOVA. Patterns in bone age Z-score were examined with two-way ANOVA, and the contributions of age, BMI-SDS, and DHEAS to bone age Z-score were analyzed with multiple regression.

RESULTS

DHEAS levels rose earlier and were less strongly correlated with age in males and females with PWS (R²=0.12 and 0.30) compared to healthy controls (R²=0.89 and 0.88) in a pattern unrelated to BMI-SDS (adjusted R²=0.076, p=0.10 for age, and 0.29 for BMI-SDS). Mid-childhood height velocity was increased in males and preserved in females with PWS before declining at the age of expected puberty (p<0.0001). Peri-adrenarchal bone age was advanced in a manner associated with DHEAS but not BMI-SDS (p<0.0001; adjusted R²=0.48, p=0.0014 for DHEAS, and 0.78 for BMI-SDS).

CONCLUSIONS

An obesity-independent increase in adrenal androgens is associated with accelerated mid-childhood growth and bone maturation in PWS.

MKRN3 circulating levels in Prader-Willi syndrome: a pilot study

CONTEXT

Hypogonadism in Prader-Willi syndrome (PWS) is generally attributed to hypothalamic dysfunction or to primary gonadal defect. MKRN3, a maternal imprinted gene located on 15q11.2-q13 region, encodes makorin ring finger protein 3, whose deficiency causes precocious puberty, an extremely rare symptom in PWS.

OBJECTIVE

This study aimed to evaluate MKRN3 levels in patients with PWS and to analyze its correlation with sexual hormone levels, insulin resistance and Body Mass Index (BMI).

METHODS

We performed an observational cross-sectional study and enrolled 80 patients with genetically confirmed diagnosis of PWS with median age of 9.6 years.

RESULTS

MKRN3 levels were measurable in 49 PWS patients with a geometric mean of 34.9 ± 22 pg/ml (median: 28.4). Unmeasurable levels of MKRN3 were found in 31 patients. No statistically significant differences were found between patients with and without measurable MKRN3 levels for any clinical, biochemical, or genetic characteristics. However, MKRN3 levels were inversely correlated with HOMA-IR index (p: 0.005) and HbA1c (p: 0.046) values. No statistically significant correlations were found between MKRN3 and LH, estradiol and testosterone concentrations, pubertal development and genetic defect, whereas a direct correlation with FSH was found (p: 0.007).

CONCLUSIONS

The typical genetic defect of PWS should lead to unmeasurable levels of the MKRN3 protein due to the inactivation of the paternal allele. Measurable circulating MKRN3 could suggest the possible involvement of tissue-specific imprinting mechanisms and other regulatory factors in gene expression. Correlations with HOMA-IR index, HbA1c, and FSH suggest peripheral actions of MKRN3, but future studies are warranted to investigate this topic.

Hypogonadism in Males With Genetic Neurodevelopmental Syndromes

Genetic syndromes that affect the nervous system may also disrupt testicular function, and the mechanisms for these effects may be interrelated. Most often neurological signs and symptoms predominate and hypogonadism remains undetected and untreated, while in other cases, a thorough evaluation of a hypogonadal male reveals previously unrecognized ataxia, movement disorder, muscle weakness, tremor, or seizures, leading to a syndromic diagnosis. Androgen deficiency in patients with neurological diseases may aggravate muscle weakness and fatigue and predispose patients to osteoporosis and obesity. The purpose of this mini review is to provide a current understanding of the clinical, biochemical, histologic, and genetic features of syndromes in which male hypogonadism and neurological dysfunction may coexist and may be encountered by the clinical endocrinologist.

Single-center real-life experience with testosterone treatment in adult men with Prader-Willi syndrome

Hypogonadism is the most frequent hormonal deficiency in individuals with Prader-Willi syndrome (PWS). This often necessitates testosterone treatment, but limited data are available to guide testosterone treatment in adult men with PWS. We aimed to evaluate the serum testosterone concentrations and adverse effects of testosterone treatment in individuals with PWS attending a specialist obesity management service. A retrospective audit was undertaken at Austin Health, Melbourne between January 2010 and April 2021. Main outcome measures were testosterone formulation and dose, serum total testosterone concentration, and prevalence of polycythemia and behavioral disturbance. Data were available for eight individuals with median baseline age 19 years (range, 19-42) and BMI 37 kg/m² (range, 27-71). Six men had obstructive sleep apnea; none were smokers. Baseline testosterone concentration was 1.8 nmol/L (IQR, 1.1-3.3) with hematocrit 0.43. Testosterone formulations were intramuscular testosterone undecanoate (TU) 1000 mg (n = 5), transdermal testosterone gel 50 mg daily (n = 1), and oral TU 80-120 mg daily (n = 2). Median total testosterone concentration was 9.7 nmol/L (IQR, 8.5-14.7). Nine of 25 (36%) hematocrit results in six patients measured >0.50 (range, 0.50-0.56). Intramuscular TU was well tolerated and was the only formulation to achieve serum total testosterone concentrations in the adult male reference range. Worsening behavioral disturbance resulted in treatment discontinuation in one individual. Our experience reinforces the need to regular monitoring of hematocrit in men with PWS treated with testosterone. However, a worsening of behavior problems was uncommon in this series.

Subcutaneous adipose tissue is a positive predictor for bone mineral density in prepubertal children with Prader-Willi syndrome independent of lean mass

OBJECTIVES

Emerging evidence suggests a fat depot-specific relationship with bone mineral density (BMD) in children, particularly in those who are overweight/obese. However, this has not yet been investigated in detail in children with Prader-Willi syndrome (PWS), a genetic syndrome characterized by a decreased lean mass (LM) and increased fat mass (FM). The objective of this study is to investigate the relationships of LM and FM, particularly fat distribution, with bone mineral parameters.

METHODS

This is a retrospective and cross-sectional study. Forty-seven prepubertal Japanese children with PWS (22 males, mean age: 6.86 years) were included. No subjects had type 2 diabetes mellitus or osteoporotic medications. LM, FM, and BMD and bone mineral content in the total body less head and the lumbar spine were measured using dual-energy x-ray absorptiometry, in addition to subcutaneous/visceral adipose tissue (SAT/VAT), and the ratio of VAT to SAT (V/S) by computed tomography at the umbilical level. Bone mineral apparent density was calculated to correct for bone size.

RESULTS

LM positively correlated with bone mineral parameters after controlling for age, sex, growth hormone (GH) treatment, and FM. Although FM did not correlate with bone mineral parameters, compartment-specific analysis revealed that SAT positively and V/S negatively correlated with bone mineral parameters after controlling for age, sex, GH treatment and LM.

CONCLUSIONS

A compartment-specific effect of FM on bone mineral parameters was noted such that SAT was a positive predictor for BMD independent of LM in prepubertal children with PWS.

Hypogonadism in the Prader-Willi syndrome from birth to adulthood: a 28-year experience in a single centre

BACKGROUND

Hypogonadism is a key feature of Prader-Willi syndrome (PWS) but clear strategies for hormone replacement are lacking.

OBJECTIVE

To evaluate gonadal status and outcome in patients attending a Scottish PWS clinic from 1991-2019.

METHODS

In 93 (35F:56M) patients, median follow-up 11.2 years, gonadal and pubertal status were assessed clinically. Pelvic ultrasound findings and basal/stimulated gonadotrophins were compared with age-matched controls.

RESULTS

Females: Of 22 patients aged >11, 9 had reached B4-5, while 5 were still at B2-3, and 6 remained prepubertal. Eight patients experienced menarche aged 9.8-21.4 years, none with a normal cycle. Uterine length and ovarian volumes were normal but uterine configuration remained immature, with low follicular counts. Gonadotrophins were unremarkable, serum estradiol 129 (70 - 520) pmol/L. Only 5 patients received oestrogen replacement. Males: Fifty-four (96%) patients were cryptorchid (9 unilateral). Weekly hCG injections resulted in unilateral/bilateral descent in 2/1 of 25 patients. Of 37 boys aged >11, 14 (9 with failed/untreated bilateral cryptorchidism) failed to progress beyond G1, 15 arrested at G2-3 (testes 3-10 ml), and 8 reached G4-5. Gonadotrophins were unremarkable except in boys at G2-5 in whom FSH was elevated: 12.3/27.3 vs 3.25/6.26 U/L in controls (p<0.001). In males aged >13, testosterone was 3.1 (0.5-8.4) nmol/L. Androgen therapy, given from 13.5-29.2 years, was stopped in 4/24 patients owing to behavioural problems.

CONCLUSION

Despite invariable hypogonadism, few females and only half the males with PWS in this study received hormone replacement. Double-blind placebo-controlled crossover trials of sex steroids are required to address unproven behavioural concerns.

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.

Prader-Willi Syndrome and Hypogonadism: A Review Article

Prader-Labhart-Willi syndrome (PWS) is a rare genetic disorder characterized by intellectual disability, behavioural problems, hypothalamic dysfunction and specific dysmorphisms. Hypothalamic dysfunction causes dysregulation of energy balance and endocrine deficiencies, including hypogonadism. Although hypogonadism is prevalent in males and females with PWS, knowledge about this condition is limited. In this review, we outline the current knowledge on the clinical, biochemical, genetic and histological features of hypogonadism in PWS and its treatment. This was based on current literature and the proceedings and outcomes of the International PWS annual conference held in November 2019. We also present our expert opinion regarding the diagnosis, treatment, care and counselling of children and adults with PWS-associated hypogonadism. Finally, we highlight additional areas of interest related to this topic and make recommendations for future studies.

Hypogonadism in Patients with Prader Willi Syndrome: A Narrative Review

Prader-Willi syndrome (PWS) is a multisystemic complex genetic disorder related to the lack of a functional paternal copy of chromosome 15q11-q13. Several clinical manifestations are reported, such as short stature, cognitive and behavioral disability, temperature instability, hypotonia, hypersomnia, hyperphagia, and multiple endocrine abnormalities, including growth hormone deficiency and hypogonadism. The hypogonadism in PWS is due to central and peripheral mechanisms involving the hypothalamus-pituitary-gonadal axis. The early diagnosis and management of hypogonadism in PWS are both important for physicians in order to reach a better quality of life for these patients. The aim of this study is to summarize and investigate causes and possible therapies for hypogonadism in PWS. Additional studies are further needed to clarify the role of different genes related to hypogonadism and to establish a common and evidence-based therapy.

Prader- Willi syndrome: An uptodate on endocrine and metabolic complications

Prader-Willi syndrome (PWS) is a genetic disorder characterized by short stature, low lean body mass, muscular hypotonia, mental retardation, behavioral abnormalities, dysmorphic features, and excessive appetite with progressive obesity. It is caused by lack of expression of genes on the paternally inherited chromosome 15q11.2-q13. This genetic disorder has an estimated prevalence that ranges between 1/10,000-1/30,000. Hypothalamic dysfunction is a common finding in PWS and it has been implicated in several manifestations of this syndrome such as hyperphagia, temperature instability, high pain threshold, sleep disordered breathing, and multiple endocrine abnormalities. These include growth hormone deficiency, central adrenal insufficiency, hypogonadism, hypothyroidism, and obesity often complicated by type 2 diabetes. The aim of this manuscript is to overview the current literature on metabolic and endocrine complications of PWS, focusing on human studies and providing insights on the physio pathological mechanisms. A careful management of metabolic and endocrine complications can contribute to improve quality of life, prevent complications, and prolong life expectancy of PW patients.

Primary gonadal failure

The term primary gonadal failure encompasses not only testicular insufficiency in 46,XY males and ovarian insufficiency in 46,XX females, but also those disorders of sex development (DSD) which result in gender assignment that is at variance with the genotype and gonadal type. In boys, causes of gonadal failure include Klinefelter and other aneuploidy syndromes, bilateral cryptorchidism, testicular torsion, and forms of 46,XY DSD such as partial androgen insensitivity. Causes in girls include Turner syndrome and other aneuploidies, galactosemia, and autoimmune ovarian failure. Iatrogenic causes in both boys and girls include the late effects of childhood cancer treatment, total body irradiation prior to bone marrow transplantation, and iron overload in transfusion-dependent thalassaemia. In this paper, a brief description of the physiology of testicular and ovarian development is followed by a section on the causes and practical management of gonadal impairment in boys and girls. Protocols for pubertal induction and post-pubertal hormone replacement - intramuscular, oral and transdermal testosterone in boys; oral and transdermal oestrogen in girls - are then given. Finally, current and future strategies for assisted conception and fertility preservation are discussed.

Central precocious puberty as a prelude of gonad dysplasia

There is increasing evidence that patients with gonad dysplasia, as characterized by absent or incomplete puberty, can also exhibit central precocious puberty (CPP). Herein, we review the reported cases that manifest with both gonad dysplasia and CPP. Further, we examine the hypothesis that these patients exhibit a normal hypothalamic-pituitary-gonadal axis, hypogonadism, and the presence of residual gonadal function, and that the onset of disease is related to early initiation of the hypothalamic-pituitary-gonadal axis. Thus, we suggest that CPP is a prelude of some partial hypogonadism.

Gonadal function and testicular histology in males with Prader-Willi syndrome

CONTEXT

Cryptorchidism is common in Prader-Willi syndrome (PWS) males, but the testicular histology in childhood remains uncertain. The association between testicular histology and long-term gonadal function in PWS males is also unknown.

OBJECTIVES

To evaluate the relationship between testicular histology in childhood and long-term gonadal function in PWS males.

PATIENTS AND METHODS

Forty men with PWS were assessed longitudinally at our institute over the past 24 years. Clinical examinations and blood tests for LH, FSH and testosterone levels were compared with normal reference values. Tissue specimens were collected during orchiopexy and analyzed based on Nistal categories.

RESULTS

Of nine testes available for pathological assessments, two showed favourable histology (Nistal I) and seven showed unfavourable histology (Nistal II or III). Of five postpubertal males with histology available, four reached puberty spontaneously, but only one reached Tanner stage 5. In a male with favourable histology, LH and FSH were high, but testosterone was normal, though below the average of the reference range. In three males with unfavourable histology, LH was normal, but FSH was highly elevated, and testosterone was at the lower limit of normal. One patient took hCG treatment to induce puberty; this patient showed favourable histology, but LH, FSH and testosterone were not elevated in adolescence.

CONCLUSIONS

Testicular histology of PWS men in childhood varies from normal to Sertoli Cell-Only Syndrome. Regardless of the testicular histology in childhood, hypogonadism in PWS adults arises as a consequence of primary testicular dysfunction with highly elevated FSH and insufficient testosterone levels.

Hypogonadism and Cryptorchidism

Congenital cryptorchidism (undescended testis) is one of the most common congenital urogenital malformations in boys. Prevalence of cryptorchidism at birth among boys born with normal birth weight ranges from 1.8 to 8.4%. Cryptorchidism is associated with a risk of low semen quality and an increased risk of testicular germ cell tumors. Testicular hormones, androgens and insulin-like peptide 3 (INSL3), have an essential role in the process of testicular descent from intra-abdominal position into the scrotum in fetal life. This explains the increased prevalence of cryptorchidism among boys with diseases or syndromes associated with congenitally decreased secretion or action of androgens, such as patients with congenital hypogonadism and partial androgen insensitivity syndrome. There is evidence to support that cryptorchidism is associated with decreased testicular hormone production later in life. It has been shown that cryptorchidism impairs long-term Sertoli cell function, but may also affect Leydig cells. Germ cell loss taking place in the cryptorchid testis is proportional to the duration of the condition, and therefore early orchiopexy to bring the testis into the scrotum is the standard treatment. However, the evidence for benefits of early orchiopexy for testicular endocrine function is controversial. The hormonal treatments using human chorionic gonadotropin (hCG) or gonadotropin-releasing hormone (GnRH) to induce testicular descent have low success rates, and therefore they are not recommended by the current guidelines for management of cryptorchidism. However, more research is needed to assess the effects of hormonal treatments during infancy on future male reproductive health.

EFFECT OF GROWTH HORMONE THERAPY IN CHILDREN WITH PRADER-WILLI SYNDROME - OUR FIRST EXPERIENCES

- Prader-Willi syndrome (PWS) is the most common cause of morbid obesity in childhood. It is the consequence of the lack of expression of genes on the paternally inherited 15q11.2-q13 region. Hyperphagia, obesity, short stature, psychomotor retardation and deterioration of behavior predominate in clinical presentation. Recombinant human growth hormone (rhGH) therapy, along with restriction of caloric intake, has become the mainstay in the management of PWS patients. Anthropometric parameters (height, body mass index (BMI)), therapy effect on carbohydrate and lipid metabolism, and occurrence of side effects were monitored in four children with PWS treated with rhGH for ≥2 years at doses of up to 1 mg/m2/day. During the follow-up, the height standard deviation score (SDS) increased in comparison with baseline values, and after ≥2 years of treatment with rhGH it was within the reference range for the general children population. BMI SDS decreased after the first year of treatment, but thereafter increased again; still, the level of BMI SDS was much better in comparison with most children with PWS of the same age and gender. RhGH therapy had no negative effect on glucose and lipid metabolism, nor caused any other adverse effect. Therapy including a customized diet for PWS, along with rhGH therapy, provided a satisfactory growth rate and prevented development of morbid obesity without side effects. This treatment approach would ensure transition of a greater number of PWS patients into adult care, where the multidisciplinary approach in care should be continued.

Bone mineral density in young adults with Prader-Willi syndrome: A randomized, placebo-controlled, crossover GH trial

CONTEXT

The prevalence of osteoporosis is increased in adults with Prader-Willi syndrome (PWS). In children with PWS, growth hormone (GH) treatment has beneficial effects on bone mineral density (BMD). BMD might deteriorate after cessation of GH at adult height (AH), while continuing GH might maintain BMD.

OBJECTIVE

To investigate the effects of GH vs placebo, and furthermore the effects of sex steroid replacement therapy (SSRT), on BMD in GH-treated young adults with PWS who had attained AH.

DESIGN

Two-year, randomized, double-blind, placebo-controlled, crossover GH study.

PATIENTS

Twenty-seven young adults with PWS were stratified for gender and BMI and then randomly and blindly assigned to receive GH (0.67 mg/m² /day) or placebo for 1 year, after which they crossed over to the alternative treatment for another year.

MEASUREMENTS

Bone mineral density of the total body (BMD_TB ) and lumbar spine (BMD_LS ) SDS were measured by dual-energy x-ray absorptiometry.

RESULTS

At AH, BMD_TB SDS was significantly lower compared to healthy peers (P < .01), while BMAD_LS SDS was similar. Both BMD_TB SDS and BMAD_LS SDS were similar during 1 year of GH vs 1 year of placebo. In hypogonadal young adults without SSRT, BMD_TB SDS and BMAD_LS SDS decreased during the 2-year study (P = .11 and P = .01), regardless of GH or placebo, while BMD_TB SDS increased in those with SSRT (P < .01).

CONCLUSIONS

Compared to GH treatment, 1 year of placebo after attainment of AH does not deteriorate BMD SDS in young adults with PWS. In addition, our data suggest that GH is not able to prevent the decline in BMD SDS in hypogonadal young adults with PWS, unless it is combined with SSRT.

The tempo of human childhood: a maternal foot on the accelerator, a paternal foot on the brake

Relative to the life history of other great apes, that of humans is characterized by early weaning and short interbirth intervals (IBIs). We propose that in modern humans, birth until adrenarche, or the rise in adrenal androgens, developmentally corresponds to the period from birth until weaning in great apes and ancestral hominins. According to this hypothesis, humans achieved short IBIs by subdividing ancestral infancy into a nurseling phase, during which offspring fed at the breast, and a weanling phase, during which offspring fed specially prepared foods. Imprinted genes influence the timing of human weaning and adrenarche, with paternally expressed genes promoting delays in childhood maturation and maternally expressed genes promoting accelerated maturation. These observations suggest that the tempo of human development has been shaped by consequences for the fitness of kin, with faster development increasing maternal fitness at a cost to child fitness. The effects of imprinted genes suggest that the duration of the juvenile period (adrenarche until puberty) has also been shaped by evolutionary conflicts within the family.

Orchidopexy in children with Prader-Willi syndrome: Results of a long-term follow-up study

INTRODUCTION

Prader-Willi syndrome (PWS) is a rare (1:20.000) genetic condition affecting both males and females. Among other features, in boys, the syndrome is characterized by cryptorchidism in 86-100% of cases, hypogonadism, delayed puberty and infertility. The aim of the present study is to appraise the results of orchidopexy in this selected population of children.

STUDY DESIGN

A follow-up study of children with PWS treated for undescended testes at a single institution over a 20-year period was performed. Patients were identified from a National PWS registry and reviewed at a special follow-up clinic. Data were collected from electronic and hard copies records and reported as median (range).

RESULTS

Thirty-three children (1-17 years) were identified. Co-morbidities were present in 22 (66%) and 15 (45%) were on growth-hormone therapy. Six patients (19%) had normal testes palpable in the scrotum; twenty-seven (81%) had undescended testes and required orchidopexy. Thirteen (48%) underwent a bilateral procedure for a total of 40 procedures. A 2-stage Fowler-Stephens orchidopexy was required in 2 (7%) testes. At surgery hypotrophic testes were documented in 6 (22%) patients. Age at orchidopexy was 1.4 years (0.5-5.5). Age at FU was 7.2 years (1.7-17). Length of follow-up is 3.5 years (0.4-14). At follow-up 16 (40%) testes were of normal size and palpable in the scrotum; 7 (17.5%) testes required redo-orchidopexy. All patients (6/33) over 16 years of age that had testosterone levels tested had values below normal limits after successful orchidopexy.

CONCLUSIONS

This study evaluates the results of orchidopexy in a large population of children with PWS. At follow-up, only 40% of testes were of normal size and in the scrotum. This information should be taken into consideration for patients' management and pre-operative parents' counseling.

Review of Prader-Willi syndrome: the endocrine approach

Prader-Willi syndrome (PWS) is a complex genetic disorder with implications on the endocrine and neurologic systems, metabolism, and behavior. Early in life, PWS is characterized by hypotonia and failure to thrive, followed by obesity and hyperphagia. Patients with PWS develop hypothalamic dysfunction which may lead growth hormone deficiency (GHD), hypogonadism, hypothyroidism, adrenal insufficiency, and poor bone mineral density (BMD). In addition to hypothalamic dysfunction, individuals with PWS have increased risk for obesity which may be complicated by metabolic syndrome and type 2 diabetes mellitus (T2DM). In this paper, we will review the current literature pertaining to the endocrine concerns of PWS and current recommendations for screening and management of these conditions.

Growth Hormone Treatment in Children With Prader-Willi Syndrome: Three Years of Longitudinal Data in Prepubertal Children and Adult Height Data From the KIGS Database

CONTEXT

Longitudinal data of children with Prader-Willi syndrome (PWS) treated with genotropin were registered in the Pfizer International Growth Database (KIGS).

OBJECTIVE

To evaluate efficacy and safety of growth hormone (GH) treatment in a large group of children with PWS.

DESIGN

Data registered in KIGS from 1987 to 2012.

SETTING

Worldwide retrospective cohort study.

PATIENTS

Patients included 522 prepubertal children treated with GH for three years and 173 children who had reached adult height. Safety analysis included 2332 children. Intervention involved GH treatment.

MAIN OUTCOME MEASURE

Height standard deviation score (SDS), body mass index (BMI) SDS, occurrence of serious adverse events, and deaths reported in KIGS.

RESULTS

In prepubertal children, mean (standard deviation) height SDS improved to -0.31 (1.34) (P < 0.05) during three years of GH treatment. In the adolescent group, height SDS improved until the start of puberty to -0.22 (1.31) (P < 0.05) but had a loss of -0.77 (0.81) during puberty, resulting in a mean adult height SDS of -1.19 (1.37). Total height gain was 0.95 (1.32) SDS. BMI SDS increased in the prepubertal group from 1.11 (2.09) to 1.53 (1.43) (P < 0.05) and did not significantly change in the adolescent group, who had a BMI SDS at an adult height of 1.78 (1.26). KIGS contained 12 death reports.

CONCLUSIONS

GH treatment in children with PWS significantly improves linear growth. BMI remains on average below +2 SDS, in contrast to the natural course of increasing obesity in PWS. Safety should be closely monitored in children with PWS, with and without GH treatment.

[Endocrine and metabolic features of female children with Prader-Willi syndrome: an analysis of 4 cases]

This article reports the clinical features and endocrine and metabolic features of 4 children with Prader-Willi syndrome (PWS). All the patients were female and aged 6-12 years at diagnosis. All of them had clinical manifestations of obesity, unusual facies, developmental retardation, and intellectual disability. Genetic detection showed that 2 patients had paternal deletion of the 15q11.2-q13 region, one patient had maternal autodiploid in the 15q11.2-q13 region, and one patient had no abnormality in the 15q11.2-q13 region. All patients had varying degrees of endocrine and metabolic disorders: 2 patients had short stature, among whom one had delayed appearance of secondary sex characteristics and the other one had type 2 diabetes; one patient had insulin resistance and no mammary gland development; one patient had a body height of P₃-P₁₀ and precocious puberty. Patients with PWS have various endocrine disorders, so long-term endocrine follow-up and management is very important.

Altered functional resting-state hypothalamic connectivity and abnormal pituitary morphology in children with Prader-Willi syndrome

Background

Prader-Willi syndrome (PWS) is a complex neurodevelopmental disorder, characterized by endocrine problems and hyperphagia, indicating hypothalamic-pituitary dysfunction. However, few studies have explored the underlying neurobiology of the hypothalamus and its functional connectivity with other brain regions. Thus, the aim of this study was to examine the anatomical differences of the hypothalamus, mammillary bodies, and pituitary gland as well as resting state functional connectivity of the hypothalamus in children with PWS.

Methods

Twenty-seven children with PWS (13 DEL, 14 mUPD) and 28 typically developing children were included. Manual segmentations by a blinded investigator were performed to determine the volumes of the hypothalamus, mammillary bodies, and pituitary gland. In addition, brain-wide functional connectivity analysis was performed using the obtained masks of the hypothalamus.

Results

Children with PWS showed altered resting state functional connectivity between hypothalamus and right and left lateral occipital complex, compared to healthy controls. In addition, children with PWS had on average a 50% smaller pituitary volume, an irregular shape of the pituitary, and a longer pituitary stalk. Pituitary volume did not increase in volume during puberty in PWS. No volumetric differences in the hypothalamus and mammillary bodies were found. In all subjects, the posterior pituitary bright spot was observed.

Conclusions

We report altered functional hypothalamic connectivity with lateral occipital complexes in both hemispheres, which are implicated in response to food and reward system, and absence of connectivity might therefore at least partially contribute to the preoccupation with food in PWS.

Anthropometric adjustments are helpful in the interpretation of BMD and BMC Z-scores of pediatric patients with Prader-Willi syndrome

Anthropometric adjustments of bone measurements are necessary in Prader-Willi syndrome patients to correctly assess the bone status of these patients. This enables physicians to get a more accurate diagnosis of normal versus abnormal bone, allow for early and effective intervention, and achieve better therapeutic results.

INTRODUCTION

Bone mineral density (BMD) is decreased in patients with Prader-Willi syndrome (PWS). Because of largely abnormal body height and weight, traditional BMD Z-scores may not provide accurate information in this patient group. The goal of the study was to assess a cohort of individuals with PWS and characterize the development of low bone density based on two adjustment models applied to a dataset of BMD and bone mineral content (BMC) from dual-energy X-ray absorptiometry (DXA) measurements.

METHODS

Fifty-four individuals, aged 5-20 years with genetically confirmed PWS, underwent DXA scans of spine and hip. Thirty-one of them also underwent total body scans. Standard Z-scores were calculated for BMD and BMC of spine and total hip based on race, sex, and age for all patients, as well as of whole body and whole-body less head for those patients with total-body scans. Additional Z-scores were generated based on anthropometric adjustments using weight, height, and percentage body fat and a second model using only weight and height in addition to race, sex, and age.

RESULTS

As many PWS patients have abnormal anthropometrics, addition of explanatory variables weight, height, and fat resulted in different bone classifications for many patients. Thus, 25-70 % of overweight patients, previously diagnosed as normal, were subsequently diagnosed as below normal, and 40-60 % of patients with below-normal body height changed from below normal to normal depending on bone parameter.

CONCLUSIONS

This is the first study to include anthropometric adjustments into the interpretation of BMD and BMC in children and adolescents with PWS. This enables physicians to get a more accurate diagnosis of normal versus abnormal BMD and BMC and allows for early and effective intervention.

Promising effects of oxytocin on social and food-related behaviour in young children with Prader-Willi syndrome: a randomized, double-blind, controlled crossover trial

BACKGROUND

Prader-Willi syndrome (PWS) is known for hyperphagia with impaired satiety and a specific behavioural phenotype with stubbornness, temper tantrums, manipulative and controlling behaviour and obsessive-compulsive features. PWS is associated with hypothalamic and oxytocinergic dysfunction. In humans without PWS, intranasal oxytocin administration had positive effects on social and eating behaviour, and weight balance.

OBJECTIVE AND HYPOTHESES

To evaluate the effects of intranasal oxytocin compared to placebo administration on social behaviour and hyperphagia in children with PWS.

DESIGN

Randomized, double-blind, placebo-controlled, crossover study in a PWS Reference Center in the Netherlands.

METHOD

Crossover intervention with twice daily intranasal oxytocin (dose range 24-48 IU/day) and placebo administration, both during 4 weeks, in 25 children with PWS (aged 6 to 14 years).

RESULTS

In the total group, no significant effects of oxytocin on social behaviour or hyperphagia were found, but in the 17 children younger than 11 years, parents reported significantly less anger (P = 0·001), sadness (P = 0·005), conflicts (P = 0·010) and food-related behaviour (P = 0·011), and improvement of social behaviour (P = 0·018) during oxytocin treatment compared with placebo. In the eight children older than 11 years, the items happiness (P = 0·039), anger (P = 0·042) and sadness (P = 0·042) were negatively influenced by oxytocin treatment compared to placebo. There were no side effects or adverse events.

CONCLUSIONS

This randomized, double-blind, placebo-controlled study suggests that intranasal oxytocin administration has beneficial effects on social behaviour and food-related behaviour in children with PWS younger than 11 years of age, but not in those older than 11 years of age.

Prader-Willi syndrome: a review of clinical, genetic, and endocrine findings

INTRODUCTION

Prader-Willi syndrome (PWS) is a multisystemic complex genetic disorder caused by lack of expression of genes on the paternally inherited chromosome 15q11.2-q13 region. There are three main genetic subtypes in PWS: paternal 15q11-q13 deletion (65-75 % of cases), maternal uniparental disomy 15 (20-30 % of cases), and imprinting defect (1-3 %). DNA methylation analysis is the only technique that will diagnose PWS in all three molecular genetic classes and differentiate PWS from Angelman syndrome. Clinical manifestations change with age with hypotonia and a poor suck resulting in failure to thrive during infancy. As the individual ages, other features such as short stature, food seeking with excessive weight gain, developmental delay, cognitive disability and behavioral problems become evident. The phenotype is likely due to hypothalamic dysfunction, which is responsible for hyperphagia, temperature instability, high pain threshold, hypersomnia and multiple endocrine abnormalities including growth hormone and thyroid-stimulating hormone deficiencies, hypogonadism and central adrenal insufficiency. Obesity and its complications are the major causes of morbidity and mortality in PWS.

METHODS

An extensive review of the literature was performed and interpreted within the context of clinical practice and frequently asked questions from referring physicians and families to include the current status of the cause and diagnosis of the clinical, genetics and endocrine findings in PWS.

CONCLUSIONS

Updated information regarding the early diagnosis and management of individuals with Prader-Willi syndrome is important for all physicians and will be helpful in anticipating and managing or modifying complications associated with this rare obesity-related disorder.

Sexual dichotomy of gonadal function in Prader-Willi syndrome from early infancy through the fourth decade

STUDY QUESTION

At what age does the type of hypogonadism, namely hypothalamic or primary gonadal defect, become established in men and women with Prader-Willi syndrome (PWS)?

SUMMARY ANSWER

The type of hypogonadism becomes established only in late adolescence and early adulthood.

WHAT IS KNOWN ALREADY

The etiology of hypogonadism in PWS is heterogeneous and the clinical expression is variable. Primary testicular failure is common in PWS men, while combinations of ovarian dysfunction and gonadotrophin deficiency are seen in women.

STUDY DESIGN, SIZE, DURATION

This is a prospective study of a cohort of 106 PWS patients followed for a mean duration of 4.5 years. Serial blood samples were obtained and assayed for gonadotrophins, inhibin B, anti-Mullerian hormone (AMH), dehydroepiandrosterone sulfate (DHEAS), testosterone (males), and estradiol (females). Results were compared with normal reference values obtained from the literature. For the purpose of this study, we defined the following age groups: infants <1 year; children 1-10 years; adolescents 11-20 years and adults >20 years.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Study participants were 49 males (aged 2 months to 36 years) and 57 females (aged 1 month to 37 years) with genetically confirmed diagnoses of PWS (deletions 60, uniparental disomy 54, imprinting center defect 2) followed in the Israel national multidisciplinary PWS clinic.

MAIN RESULTS AND THE ROLE OF CHANCE

Serum LH levels were in the normal range (1.0-6.0 mIU/ml) for 7/10 adult men, and high in 3, while FSH (normal range 1.0-6.1 mIU/ml) was elevated (34.4 ± 11.5 mIU/ml) in 6 and normal (3.5 ± 1.6 mIU/ml) in 4 men. Testosterone was low (5.7 ± 3.4 nmol/l) compared with the normal range of 12.0-34.5 nmol/l in the reference population in all men >20 years. AMH showed a normal decrease with age, despite low testosterone levels. Inhibin B was normal (241 ± 105 pg/ml) in infant boys, but low or undetectable in most adult men. Hormonal profiles were more heterogeneous in women than in men. Estradiol was consistently detectable in only 7/13 adult women. Inhibin B was low or undetectable in all PWS females although occasional samples showed levels within the normal range of 15-95 pg/ml. Vaginal bleeding was reported to occur for the first time in eight women at a median age of 20 years (13-34 years), but only one had regular monthly menses. The type of hypogonadism (primary or secondary) in PWS can be determined only after age 20 years.

LIMITATIONS, REASONS FOR CAUTION

The study cohort was heterogeneous, showing variability in BMI, cognitive disability and medical treatment.

WIDER IMPLICATIONS OF THE FINDINGS

Demonstration of the natural history of reproductive hormone development in PWS suggests that androgen replacement may be indicated for most PWS boys in mid-adolescence. Recommendations for hormone replacement in PWS women need to be individually tailored, serial measurements of inhibin B should be performed, and contraception should be considered in those women who may have the potential for fertility.

Characterization of minipuberty in infants with Prader-Willi syndrome

BACKGROUND

Minipuberty describes transient activation of the hypothalamic-pituitary-gonadal axis occurring during the first few months of life. Hormone levels during minipuberty were described in only a few Prader-Willi syndrome (PWS) infant boys and have not been reported in PWS infant girls.

OBJECTIVES

To measure gonadotropins and gonadal hormones in PWS male and female infants and assess gender-specific patterns of hormone secretion.

METHODS

Hormone levels in 14 (9 male, 5 female) PWS infants ages 1-3 months were compared with reference ranges for normal infants and in 44 prepubertal PWS children (27 female, 17 male).

RESULTS

Compared to prepubertal boys, hormone levels (median and range) for PWS infant boys were increased: LH 2.8 mIU/ml (1.2-6.2), FSH 4.4 mIU/ml (1.0-19.5), testosterone 4.0 nmol/l (3.0-7.0), inhibin B 219 pg/ml (141-325), and AMH 79 ng/ml (45-157). Hormone levels in infant girls were not significantly different from levels in prepubertal girls. LH, inhibin B, and AMH were higher in male infants than in female infants. LH/FSH ratios were 0.56 (0.24-1.77) in boys versus 0.09 (0.04-0.17) in girls (p = 0.003).

CONCLUSIONS

Hormone levels in PWS infant boys are in the expected minipuberty range. By contrast, reproductive hormones in most PWS infant girls did not differ from levels in prepubertal girls.

The small RNA content of human sperm reveals pseudogene-derived piRNAs complementary to protein-coding genes

At the end of mammalian sperm development, sperm cells expel most of their cytoplasm and dispose of the majority of their RNA. Yet, hundreds of RNA molecules remain in mature sperm. The biological significance of the vast majority of these molecules is unclear. To better understand the processes that generate sperm small RNAs and what roles they may have, we sequenced and characterized the small RNA content of sperm samples from two human fertile individuals. We detected 182 microRNAs, some of which are highly abundant. The most abundant microRNA in sperm is miR-1246 with predicted targets among sperm-specific genes. The most abundant class of small noncoding RNAs in sperm are PIWI-interacting RNAs (piRNAs). Surprisingly, we found that human sperm cells contain piRNAs processed from pseudogenes. Clusters of piRNAs from human testes contain pseudogenes transcribed in the antisense strand and processed into small RNAs. Several human protein-coding genes contain antisense predicted targets of pseudogene-derived piRNAs in the male germline and these piRNAs are still found in mature sperm. Our study provides the most extensive data set and annotation of human sperm small RNAs to date and is a resource for further functional studies on the roles of sperm small RNAs. In addition, we propose that some of the pseudogene-derived human piRNAs may regulate expression of their parent gene in the male germline.

Management of testosterone therapy in adolescents and young men with hypogonadism: are we following adult clinical practice guidelines?

OBJECTIVE

Male hypogonadism is a common disorder that is associated with low bone density, poor muscle mass, anemia, and sexual dysfunction. The Endocrine Society recently published a Clinical Practice Guideline for testosterone therapy in androgen-deficient men. Because treatment is frequently initiated in adolescence, the goal of this quality improvement initiative was to assess whether pediatric endocrinologists at a large tertiary care center follow these guidelines and to identify opportunities for improvement.

DESIGN

We performed a retrospective chart review at Boston Children's Hospital. Inclusion criteria were as follows: current age ≥16 years, diagnosis of hypogonadism, and testosterone replacement therapy. Data were collected about current age, age at treatment initiation, diagnoses, pre- and on-treatment testosterone levels, route of testosterone administration and dose, bone density, hematocrit levels, and adherence with therapy.

RESULTS

Fifty-nine patients were included. Fourteen (24%) were prescribed lower testosterone doses than those recommended in the Clinical Practice Guideline. Seven (12%) had no pre-treatment testosterone levels, and 10 (17%) had no on-treatment levels. In 49 patients with on-treatment testosterone levels, 36 had at least one value that was lower than the adult reference range. Ten (28%) of the 36 men with low testosterone levels had no dose adjustments. Thirty-seven (63%) of the 59 patients had no dual-energy X-ray absorptiometry scans, and 18 (31%) did not have hematocrit levels.

CONCLUSIONS

Pediatric endocrinologists in this review did not consistently follow the Clinical Practice Guideline for testosterone therapy in hypogonadal adult males. Strategies that improve adherence to guidelines could help maximize the benefits of therapy and minimize treatment-associated risks.

Prader-Willi syndrome: a case report with atypical developmental features

OBJECTIVE

To describe the case of a male Prader-Willi syndrome (PWS) patient with atypical development features.

DESCRIPTION

We report the case of a male adolescent with confirmed diagnosis of PWS which presents atypical phenotype. The patient progressed with spontaneous and complete pubertal development, stature in the normal range, and weight control without any pharmacological treatment, except metformin.

COMMENTS

PWS is an imprinting paternally inherited disorder of 15q11-13 characterized by hypotonia in infant age, hyperphagia, varied degrees of mental retardation, behavior problems, hypogonadism, short stature, and other less common findings.

Testes in infants with Prader-Willi syndrome: human chorionic gonadotropin treatment, surgery and histology

PURPOSE

Boys with Prader-Willi syndrome often have undescended testes. Prospective studies on the treatment of cryptorchidism in these patients are lacking. We evaluated the effects of human chorionic gonadotropin administration on testis position in 16 males with Prader-Willi syndrome. In patients who subsequently underwent orchiopexy biopsy was taken and testis histology was evaluated.

MATERIALS AND METHODS

A total of 16 boys (median age 1.6 years, IQR 1.2 to 1.8) with Prader-Willi syndrome and cryptorchidism underwent human chorionic gonadotropin stimulation test. After a positive test human chorionic gonadotropin treatment was initiated. Patients received 250 to 500 IU (depending on age) intramuscularly twice weekly for 6 weeks.

RESULTS

We found 1 testis in a stable scrotal position, 1 vanished testis and 1 atrophic abdominal testis. Of 29 testes responding to human chorionic gonadotropin 23% reached a stable scrotal position, 62% reached a lower position and 14% did not change position. Thus, 22 testes required orchiopexy. Of 17 obtained biopsies in 12 patients 2 showed germ cells in more than 60% of seminiferous tubules, 3 in 30% to 60% and 7 in less than 30%. In addition, 4 boys had Sertoli cell only syndrome and 1 had a vanished testis. In patients undergoing orchiopexy younger age and increased inhibin B and testosterone levels after human chorionic gonadotropin stimulation were associated with a greater number of germ cell containing tubules.

CONCLUSIONS

Human chorionic gonadotropin administration resulted in an anatomically lower testis position in most of our patients with Prader-Willi syndrome, and 23% of testes reached a stable scrotal position. Of the cases 76% required orchiopexy to ensure a stable position in the scrotum.

Spreading the clinical window for diagnosing fetal-onset hypogonadism in boys

In early fetal development, the testis secretes - independent of pituitary gonadotropins - androgens and anti-Müllerian hormone (AMH) that are essential for male sex differentiation. In the second half of fetal life, the hypothalamic-pituitary axis gains control of testicular hormone secretion. Follicle-stimulating hormone (FSH) controls Sertoli cell proliferation, responsible for testis volume increase and AMH and inhibin B secretion, whereas luteinizing hormone (LH) regulates Leydig cell androgen and INSL3 secretion, involved in the growth and trophism of male external genitalia and in testis descent. This differential regulation of testicular function between early and late fetal periods underlies the distinct clinical presentations of fetal-onset hypogonadism in the newborn male: primary hypogonadism results in ambiguous or female genitalia when early fetal-onset, whereas it becomes clinically undistinguishable from central hypogonadism when established later in fetal life. The assessment of the hypothalamic-pituitary-gonadal axis in male has classically relied on the measurement of gonadotropin and testosterone levels in serum. These hormone levels normally decline 3-6 months after birth, thus constraining the clinical evaluation window for diagnosing male hypogonadism. The advent of new markers of gonadal function has spread this clinical window beyond the first 6 months of life. In this review, we discuss the advantages and limitations of old and new markers used for the functional assessment of the hypothalamic-pituitary-testicular axis in boys suspected of fetal-onset hypogonadism.

Endocrine manifestations and management of Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a complex genetic disorder, caused by lack of expression of genes on the paternally inherited chromosome 15q11.2-q13. In infancy it is characterized by hypotonia with poor suck resulting in failure to thrive. As the child ages, other manifestations such as developmental delay, cognitive disability, and behavior problems become evident. Hypothalamic dysfunction has been implicated in many manifestations of this syndrome including hyperphagia, temperature instability, high pain threshold, sleep disordered breathing, and multiple endocrine abnormalities. These include growth hormone deficiency, central adrenal insufficiency, hypogonadism, hypothyroidism, and complications of obesity such as type 2 diabetes mellitus. This review summarizes the recent literature investigating optimal screening and treatment of endocrine abnormalities associated with PWS, and provides an update on nutrition and food-related behavioral intervention. The standard of care regarding growth hormone therapy and surveillance for potential side effects, the potential for central adrenal insufficiency, evaluation for and treatment of hypogonadism in males and females, and the prevalence and screening recommendations for hypothyroidism and diabetes are covered in detail. PWS is a genetic syndrome in which early diagnosis and careful attention to detail regarding all the potential endocrine and behavioral manifestations can lead to a significant improvement in health and developmental outcomes. Thus, the important role of the provider caring for the child with PWS cannot be overstated.

Testosterone replacement therapy to improve secondary sexual characteristics and body composition without adverse behavioral problems in adult male patients with Prader-Willi syndrome: an observational study

Prader-Willi syndrome (PWS), a complex genetic disorder, arises from suppressed expression of paternally inherited imprinted genes on chromosome 15q11-q13. Characteristics include short stature, intellectual disability, behavioral problems, hypogonadism, obesity, and reduced bone and muscle mass. Testosterone replacement (TR) remains controversial due to concerns regarding behavioral problems. To evaluate the effects of TR on secondary sexual characteristics, body composition, and behavior in adult males with PWS, 22 male PWS patients over the age of 16 with behavioral scores of less than grade 4 on the Modified Overt Aggression Scale (MOAS) underwent monthly intramuscular TR (125 mg). Pubertal change, body composition and behavior were evaluated before and after 24 months of therapy. Serum testosterone, LH, and FSH did not change. Increased pubic hair was observed in 16 of 22 patients (72.7%). Percent body fat decreased from 47.55 ± 2.06% to 39.75 ± 1.60% (n = 18) (P = 0.018). Bone mineral density increased from 0.8505 ± 0.0426 g/cm(2) to 0.9035 ± 0.0465 g/cm(2) (n = 18) (P = 0.036), and lean body mass increased from 18093.4 ± 863.0 g to 20312.1 ± 1027.2 g (n = 18) (P = 0.009). The MOAS was unchanged, from 4.5 ± 2.0 at the beginning of the study to 3.0 ± 1.7 at the end of study indicating no increase in aggression. No behavioral problems were observed. Based on this pilot study, TR with 125 mg monthly is a potentially safe and useful intervention for adult males with PWS.

The prepubertal testis: biomarkers and functions

PURPOSE OF REVIEW

Biomarkers of prepubertal testicular function have become widely available only in recent years. The aim of this review is to update the knowledge on key biomarkers used to assess hypogonadism in boys.

RECENT FINDINGS

Sertoli cells are the most representative cells of the prepubertal testis. Anti-Müllerian hormone and inhibin B are essential biomarkers of Sertoli cell function. Also, INSL3 arises as an additional marker of Leydig cell dysfunction.

SUMMARY

The widespread use of these biomarkers has enhanced our knowledge on the pathophysiology and diagnosis of prepubertal male hypogonadism. Beyond their well known germ-cell toxicity, oncologic treatments may also affect Sertoli cell function. Pathophysiology is not the same in all aneuploidies leading to infertility: while hypogonadism is not evident until mid-puberty in Klinefelter syndrome, it is established in early infancy in Down syndrome. In Noonan syndrome, the occurrence of primary hypogonadism depends on the existence of cryptorchidism, and Prader-Willi syndrome may present with either primary or combined forms of hypogonadism. Prepubertal testicular markers have also provided insights into the effects of environmental disruptors on gonadal function from early life, and helped dissipate concerns about testicular function in boys born preterm or small for gestational age or conceived by assisted reproductive technique procedures.

Two years of growth hormone treatment in adults with Prader-Willi syndrome do not improve the low BMD

BACKGROUND

Bone mineral density (BMD) in adult patients with Prader-Willi syndrome (PWS) might be low due to high bone turnover.

OBJECTIVES

The objective of the study was to investigate bone mass in a group of adult PWS subjects and study the effects of GH treatment on BMD and markers of bone turnover.

DESIGN

Forty-six adults with genetically verified PWS were randomized to GH or placebo for 12 months, followed by open prospective GH for 24 additional months. BMD at the lumbar spine (LS) L1-4, the total hip, and the total body was assessed by dual-energy x-ray absorptiometry at baseline and every 12th month thereafter. Markers of bone turnover were measured at baseline and at the end of the controlled study.

RESULTS

In this cohort of adult subjects with PWS, baseline BMD was reduced in all compartments compared with the reference (Z-scores). Men had lower Z-scores BMD than women in LS and total body (P < .05). With 12 months of GH, LS-BMD was significantly reduced compared with placebo. No changes in BMD were observed with continuous GH treatment for 24 months. The bone formation markers increased with GH therapy compared with placebo, whereas the resorption marker did not change.

CONCLUSIONS

Adult PWS subjects, especially the men, have low bone mass that was not improved with GH treatment for 2 years. Because PWS subjects are short, BMD might be underestimated and should be adjusted for. Further studies, with adequate GH and sex hormone replacement throughout puberty and early adult life, are needed to better characterize PWS.

Recent updates on recombinant human growth hormone outcomes and adverse events

PURPOSE OF REVIEW

To provide up-to-date information on outcomes and adverse events associated with the use of recombinant human growth hormone (rhGH). We will focus on patients with Prader Willi Syndrome and Idiopathic Short Stature. We will also discuss recent reports on long-term adverse events from the European database.

RECENT FINDINGS

Prader Willi Syndrome is associated with hypogonadism, which does not appear to be affected by treatment with rhGH. However, there is new evidence that treatment may improve cognition. For patients with Idiopathic Short Stature, the gain in near adult height with treatment with rhGH appears to be 3-4 cm. Although a recent analysis of this group shows that certain patient characteristics may help identify those most likely to have a good response to treatment. Additionally, the safety and appropriateness of growth hormone treatments in Europe study released preliminary data from patients treated in two separate locations that showed conflicting information on risk of mortality from treatment with rhGH.

SUMMARY

Although we will continue to receive new information regarding the safety and effects of treatment with rhGH, it is important to discuss the risks and benefits with our patients. Additionally, it is incumbent on us to help guide the treatment to those most likely to benefit.

Anti-müllerian hormone: a valuable addition to the toolbox of the pediatric endocrinologist

Anti-Müllerian hormone (AMH), secreted by immature Sertoli cells, provokes the regression of male fetal Müllerian ducts. FSH stimulates AMH production; during puberty, AMH is downregulated by intratesticular testosterone and meiotic germ cells. In boys, AMH determination is useful in the clinical setting. Serum AMH, which is low in infants with congenital central hypogonadism, increases with FSH treatment. AMH is also low in patients with primary hypogonadism, for instance in Down syndrome, from early postnatal life and in Klinefelter syndrome from midpuberty. In boys with nonpalpable gonads, AMH determination, without the need for a stimulation test, is useful to distinguish between bilaterally abdominal gonads and anorchism. In patients with disorders of sex development (DSD), serum AMH determination helps as a first line test to orientate the etiologic diagnosis: low AMH is indicative of dysgenetic DSD whereas normal AMH is suggestive of androgen synthesis or action defects. Finally, in patients with persistent Müllerian duct syndrome (PMDS), undetectable serum AMH drives the genetic search to mutations in the AMH gene, whereas normal or high AMH is indicative of an end organ defect due to AMH receptor gene defects.

Loss-of-function mutations in IGSF1 cause an X-linked syndrome of central hypothyroidism and testicular enlargement

Congenital central hypothyroidism occurs either in isolation or in conjunction with other pituitary hormone deficits. Using exome and candidate gene sequencing, we identified 8 distinct mutations and 2 deletions in IGSF1 in males from 11 unrelated families with central hypothyroidism, testicular enlargement and variably low prolactin concentrations. IGSF1 is a membrane glycoprotein that is highly expressed in the anterior pituitary gland, and the identified mutations impair its trafficking to the cell surface in heterologous cells. Igsf1-deficient male mice show diminished pituitary and serum thyroid-stimulating hormone (TSH) concentrations, reduced pituitary thyrotropin-releasing hormone (TRH) receptor expression, decreased triiodothyronine concentrations and increased body mass. Collectively, our observations delineate a new X-linked disorder in which loss-of-function mutations in IGSF1 cause central hypothyroidism, likely secondary to an associated impairment in pituitary TRH signaling.

Ovarian function and reproductive hormone levels in girls with Prader-Willi syndrome: a longitudinal study

CONTEXT

The etiology of hypogonadism in girls with Prader-Willi syndrome (PWS) remains uncertain.

OBJECTIVES

The aim of the study was to evaluate gonadal function longitudinally in girls and female adolescents with PWS.

MEASUREMENTS

We performed a longitudinal assessment of anti-müllerian hormone (AMH), gonadotropins, estradiol (E(2)), inhibin B and A, and pubertal development in girls and female adolescents with PWS.

PATIENTS AND METHODS

Sixty-one girls participating in the Dutch PWS Cohort study participated in the study. Serum AMH, gonadotropins, E(2), and inhibin B and A levels were compared with reference values.

RESULTS

AMH levels in girls and female adolescents with PWS were comparable to reference levels between 6 months and 22 yr of age. From 10 yr of age, FSH and LH levels increased to above the 5th percentile compared to reference levels. E(2) and inhibin B levels were in the low normal range in the majority, and inhibin A levels were low but detectable in almost half the female adolescents with PWS. The median age at puberty onset was comparable, but the median ages at attaining Tanner M3 (P = 0.05) and M4 (P < 0.0001) were significantly higher in girls with PWS than in healthy references.

CONCLUSION

Our study shows that the primordial follicle pool and number of small antral follicles are conserved in girls and female adolescents with PWS. We found no classical hypogonadotropic hypogonadism. However, maturation of follicles and progression of pubertal development are impaired, which might be due to dysregulation of LH secretion. Because these impairments are not absolute, ovulation and thus conception cannot be ruled out in individual female adolescents with PWS.

Endocrine problems in children with Prader-Willi syndrome: special review on associated genetic aspects and early growth hormone treatment

Prader-Willi syndrome (PWS) is a complex multisystem genetic disorder characterized by hypothalamic-pituitary dysfunction. The main clinical features include neonatal hypotonia, distinctive facial features, overall developmental delay, and poor growth in infancy, followed by overeating with severe obesity, short stature, and hypogonadism later in development. This paper reviews recent updates regarding the genetic aspects of this disorder. Three mechanisms (paternal deletion, maternal disomy, and deficient imprinting) are recognized. Maternal disomy can arise because of 4 possible mechanisms: trisomy rescue (TR), gamete complementation (GC), monosomy rescue (MR), and postfertilization mitotic nondisjunction (Mit). Recently, TR/GC caused by nondisjunction at maternal meiosis 1 has been identified increasingly, as a result of advanced maternal childbearing age in Korea. We verified that the d3 allele increases the responsiveness of the growth hormone (GH) receptor to endogenous GH. This paper also provides an overview of endocrine dysfunctions in children with PWS, including GH deficiency, obesity, sexual development, hypothyroidism, and adrenal insufficiency, as well as the effects of GH treatment. GH treatment coupled with a strictly controlled diet during early childhood may help to reduce obesity, improve neurodevelopment, and increase muscle mass. A more active approach to correct these hormone deficiencies would benefit patients with PWS.

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.