Autoimmune pituitary involvement in Prader-Willi syndrome: new perspective for further research.

The role of antipituitary antibodies in the pathophysiology of pituitary hormone deficiency has been increasingly elucidated over the last decade. Prader-Willi syndrome is a genetic disorder which includes hypothalamic/pituitary dysfunction as one of its main features. We looked for autoimmune pituitary involvement in 55 adults with Prader-Willi syndrome, discovering that about 30% of them have a positive titer of antipituitary antibodies. Although the presence of these autoantibodies could only be an "epiphenomenon", our results suggest that autoimmune mechanisms might contribute, at least in part, to the pituitary impairment of Prader-Willi syndrome, and in addition to genetically determined dysfunction of the central nervous system. This paper provides a new perspective on pituitary impairment in these patients, suggesting that the search for hypophisitis could be a reasonable and interesting field for further research.

Analysis of saliva samples in patients with Prader-Willi syndrome.

Patients affected by Prader-Willi Syndrome (PWS) usually show orofacial dysfunction, poor oral hygiene, severe tooth wear, generalized caries and thick sticky saliva. The aim of this study was to evaluate molecular/ionic changings in PWS patients compared to controls, as well as unstimulated salivary flow rate (SFR); 7 patients with a mean age of 20.0±5.45 years were enrolled in the study group (PWS group) and 5 patients with a mean age of 22.6±3.05 years, in the control group. Results showed a greater Na+ (p=0.003), Cl+ (p=0.004) and P (p=0.001) concentration in saliva of PWS group as well as a greater concentration of secretory IgA (p=0.003) with a reduction of SFR (p=0.004) compared to controls. A Spearman’s analysis (based on the SFR of both groups) revealed an inverse correlation with Na (rho=-0.747), Cl (rho=-0.723), P (rho=-0.637) and sIgA (rho=-0.707) concentration and SFR, when linear regression model was performed only P and SFR were interdependent (ß=-0.748; p=0.005).

Diabetes mellitus in children and adolescents with genetic syndromes.

BACKGROUND: Several genetic syndromes are associated with diabetes mellitus (DM). This study aimed to analyse data from the DPV database with regard to frequency, treatment strategies and long-term complications in paediatric DM patients with genetic syndromes, including Turner syndrome (TS), Prader-Willi syndrome (PWS), Friedreich ataxia (FA), Alström syndrome (AS), Klinefelter syndrome (KS), Bardet-Biedl syndrome (BBS), Berardinelli-Seip syndrome (BSS) and Down syndrome (DS). METHODS: Longitudinal data for 43 521 patients with DM onset at age < 20 years were collected from 309 treatment centres in Germany and Austria using the DPV software. Data included anthropometric parameters, type of diabetes, mean age, age at diabetes onset, daily insulin dose, HbA 1c , micro- and macroalbuminuria, retinopathy and dyslipidaemia. Descriptive statistics and standard statistical tests were used for data analysis. RESULTS: In total, 205 DM patients had one of the following syndromes: DS (141 patients), TS (24), PWS (23), FA (5), AS (5), KS (4), BBS (2) and BSS (1). Diabetes-specific antibodies were positive in the majority of patients with DS, TS and FA. CONCLUSION: Despite the well-known association between DM and certain syndromic disorders, the number of affected patients in the German and Austrian paediatric diabetic population is very low. Nevertheless, physicians should be aware of syndromic forms of diabetes. Joint multicentre analyses are needed to draw relevant conclusions.

An immunological basis of hyperphagia driven by GABAergic dysfunction in Prader-Willi Syndrome.

Impaired immune function is increasingly seen as a core element of various neurological, psychiatric, and developmental disorders but has not yet been investigated in subjects with Prader-Willi Syndrome. We hypothesize that the emergence and the progression of PWS may be regulated by immune dysfunction involving auto-antibodies and miRNA driven by GABAergic dysfunction. Future research testing this hypothesis is discussed.

Prader-Willi syndrome is associated with activation of the innate immune system independently of central adiposity and insulin resistance.

BACKGROUND: Subjects with Prader-Willi syndrome (PWS) have a reduced life expectancy due to cardiovascular disease. Increased systemic low-grade inflammation is postulated as a contributor, despite reported lower visceral fat mass and increased insulin sensitivity. OBJECTIVES: Our aim was to compare inflammatory markers and arterial stiffness in PWS and adiposity-matched obese control subjects. DESIGN: We conducted a cross-sectional cohort study comparing 12 PWS subjects, 12 obese subjects matched for percentage body fat and central abdominal fat mass, and 10 healthy normal-weight subjects. MAIN OUTCOME MEASURES: Dual-energy x-ray absorptiometry was used to assess body composition, flow cytometry to quantify activation markers on immun e cells, and ELISA for measurement of C-reactive protein, adiponectin, and IL-6. Insulin resistance was estimated by homeostasis model assessment and arterial stiffness by applanation tonometry. RESULTS: PWS and obese subjects had similarly increased homeostasis model assessment and arterial stiffness. Nevertheless, PWS subjects showed significantly higher IL-6 (4.9 + or - 1.0 vs. 2.5 + or - 0.4 pg/ml; P = 0.02) and nonsignificantly higher C-reactive protein (10.5 + or - 3.2 vs. 4.0 + or - 1.0 ng/ml; P = 0.08). Neutrophil activation markers CD66b and CD11b were higher in PWS compared to obese subjects (P < 0.01), reflecting an activated innate immune system. These markers were positively related to central adiposity in lean and obese subjects (r = 0.49; P < 0.05), but not in PWS subjects. CONCLUSIONS: PWS subjects compared to adiposity-matched obese subjects demonstrate similar insulin resistance but increased low-grade inflammation. The dissociation of inflammation and central adiposity suggests that activation of innate immunity may be either a specific genetic feature of PWS or linked to the commonly associated obstructive sleep apnea syndrome, and might offer a treatment target to reduce cardiovascular disease.

Characteristics of cardiac and vascular structure and function in Prader-Willi syndrome.

OBJECTIVE: Prader-Willi syndrome (PWS) is a genetic obesity syndrome characterized by hyperphagia, behavioural disturbance and intellectual disability. PWS appears to be associated with a high incidence of sudden death, suspected to be cardiopulmonary in origin. We therefore sought to provide an assessment of cardiac and vascular structure and function in patients with PWS. PATIENTS: Nine patients with genetically confirmed PWS, mean age 28 years, body mass index (BMI) 42 kg/m2, were compared with nine age- and gender-matched lean controls. MEASUREMENTS: Lipid parameters, high-sensitivity C-reactive protein (hs-CRP) and fasting glucose and insulin were measured. To assess cardiac structure and function, a resting electrocardiogram (ECG), exercise stress test, 24-h continuous ECG monitoring, and echocardiogram were obtained. Patients and control subjects also underwent comprehensive noninvasive vascular assessment, including venous-occlusion forearm plethysmography, brachial artery flow-mediated dilatation (FMD), radial artery tonometry and carotid intima-media thickness (IMT) measurements. RESULTS: All patients with PWS had significantly elevated hs-CRP (> 3.0 mg/l) (mean 11.5 mg/l, median 11.47, interquartile range: 4.48-15.8 mg/l), compared with controls (P < 0.001). Five of nine patients with PWS had subnormal exercise capacity (< 4 mets on exercise stress testing). Twenty-four-hour ECG monitoring revealed prolonged sinus pauses in one patient, up to 4.8 s, requiring pacemaker insertion. Microvascular function as assessed by peak hyperaemic flow response was decreased in PWS (6.1 +/- 1.0 times baseline flow vs. controls 13.5 +/- 1.6 times baseline flow, P = 0.01). Other measures were similar between PWS and controls. CONCLUSIONS: This group of PWS patients had significantly raised levels of the inflammatory marker hs-CRP and evidence of microcirculatory dysfunction, both of which are associated with coronary artery disease and early sudden death. The sinus node dysfunction may in itself be a risk factor for sudden cardiac death.

Symptomatic narcolepsy, cataplexy and hypersomnia, and their implications in the hypothalamic hypocretin/orexin system.

Human narcolepsy is a chronic sleep disorder affecting 1:2000 individuals. The disease is characterized by excessive daytime sleepiness, cataplexy and other abnormal manifestations of REM sleep, such as sleep paralysis and hypnagogic hallucinations. Recently, it was discovered that the pathophysiology of (idiopathic) narcolepsy-cataplexy is linked to hypocretin ligand deficiency in the brain and cerebrospinal fluid (CSF), as well as the positivity of the human leukocyte antigen (HLA) DR2/DQ6 (DQB1*0602). The symptoms of narcolepsy can also occur during the course of other neurological conditions (i.e. symptomatic narcolepsy). We define symptomatic narcolepsy as those cases that meet the International Sleep Disorders Narcolepsy Criteria, and which are also associated with a significant underlying neurological disorder that accounts for excessive daytime sleepiness (EDS) and temporal associations. To date, we have counted 116 symptomatic cases of narcolepsy reported in literature. As, several authors previously reported, inherited disorders (n=38), tumors (n=33), and head trauma (n=19) are the three most frequent causes for symptomatic narcolepsy. Of the 116 cases, 10 are associated with multiple sclerosis, one case of acute disseminated encephalomyelitis, and relatively rare cases were reported with vascular disorders (n=6), encephalitis (n=4) and degeneration (n=1), and hererodegenerative disorder (three cases in a family). EDS without cataplexy or any REM sleep abnormalities is also often associated with these neurological conditions, and defined as symptomatic cases of EDS. Although it is difficult to rule out the comorbidity of idiopathic narcolepsy in some cases, review of the literature reveals numerous unquestionable cases of symptomatic narcolepsy. These include cases with HLA negative and/or late onset, and cases in which the occurrences of the narcoleptic symptoms are parallel with the rise and fall of the causative disease. A review of these cases (especially those with brain tumors), illustrates a clear picture that the hypothalamus is most often involved. Several cases of symptomatic cataplexy (without EDS) were also reported and in contrast, these cases appear to be often associated with non-hypothalamic structures. CSF hypocretin-1 measurement were also carried out in a limited number of symptomatic cases of narcolepsy/EDS, including narcolepsy/EDS associated with tumors (n=5), head trauma (n=3), vascular disorders (n=5), encephalopathies (n=3), degeneration (n=30), demyelinating disorder (n=7), genetic/congenital disorders (n=11) and others (n=2). Reduced CSF hypocretin-1 levels were seen in most symptomatic narcolepsy cases of EDS with various etiologies and EDS in these cases is sometimes reversible with an improvement of the causative neurological disorder and an improvement of the hypocretin status. It is also noted that some symptomatic EDS cases (with Parkinson diseases and the thalamic infarction) appeared, but they are not linked with hypocretin ligand deficiency. In contrast to idiopathic narcolepsy cases, an occurrence of cataplexy is not tightly associated with hypocretin ligand deficiency in symptomatic cases. Since CSF hypocretin measures are still experimental, cases with sleep abnormalities/cataplexy are habitually selected for CSF hypocretin measures. Therefore, it is still not known whether all or a large majority of cases with low CSF hypocretin-1 levels with CNS interventions, exhibit EDS/cataplexy. It appears that further studies of the involvement of the hypocretin system in symptomatic narcolepsy and EDS are helpful to understand the pathophysiological mechanisms for the occurrence of EDS and cataplexy.

Hypersomnia in the Prader Willi syndrome: clinical-electrophysiological features and underlying factors.

OBJECTIVE: Excessive daytime sleepiness is a common symptom in Prader Willi syndrome (PWs). Sleep disordered breathing (SDB) and narcoleptic traits such as REM sleep onsets (SOREMPs) have been reported in these subjects. We evaluated nighttime and daytime sleep patterns in patients with PWs in order to clarify the nature of their hypersomnia. DESIGN AND METHODS: We performed overnight continuous EEG-polysomnographic studies (with breathing monitoring included) in 14 subjects (6 M,8 F; mean age 17 years, range 8-37) affected by PWs unselected for sleep disturbances. Ten patients underwent a Multiple Sleep Latency Test (MSLT) the day following the nocturnal sleep studies. Patients assessment was completed by means of immunogenetic characterization. RESULTS: Nocturnal polysomnographic investigation documented sleep related breathing abnormalities such as central apneas, hypopneas or hypoventilation which mainly occurred during REM sleep in 8 subjects and did not cause sleep disruption. Only 4 subjects presented an increase in the Respiratory Disorder Index (RDI) slightly above the normal limits. In 8 subjects out of 10, with and without SDB, the mean daytime sleep latency could be considered abnormal according to the Tanner staging of pubertal development. Five patients showed at least two SOREMPs at MSLT. Subjects with and without SOREMPs had, respectively, a mean age of 18.6 SD 7.9 (4 M, 1 F) and 14.5 SD 2.9 (4 F, 1 M). The paternal deletion:uniparental dysomy ratio at genotypic characterization was 4:1 and 3.5:1 in subjects with and without SOREMPs, respectively. No patient presented DR-15 nor Dq-6. CONCLUSIONS: Excessive sleepiness is a frequent disturbance in PWs. Subgroups of PW patients show hypersomnolence and SOREMPs. Sleep disordered breathing appears to have a limited role in the genesis of hypersomnia which not seems on the other hand attributable to the coexistence of narcolepsy phenotype. Hypersomnia in PW syndrome is likely to mainly be attributable to a primary hypothalamic dysfunction. The potential interacting role of other factors such as subjects age, sex and genetic pattern is suggested and deserve further investigation.