Breathing disorders in Prader-Willi syndrome: the role of obesity, growth hormone treatment and upper respiratory tract infections

Sleep disorders in Prader-Willi syndrome, evidence from animal models and humans

Prader-Willi Syndrome (PWS) is a complex genetic disorder with multiple cognitive, behavioral and endocrine dysfunctions. Sleep alterations and sleep disorders such as Sleep-disordered breathing and Central disorders of hypersomnolence are frequently recognized (either isolated or in comorbidity). The aim of the review is to highlight the pathophysiology and the clinical features of sleep disorders in PWS, providing the basis for early diagnosis and management. We reviewed the genetic features of the syndrome and the possible relationship with sleep alterations in animal models, and we described sleep phenotypes, diagnostic tools and therapeutic approaches in humans. Moreover, we performed a meta-analysis of cerebrospinal fluid orexin levels in patients with PWS; significantly lower levels of orexin were detected in PWS with respect to control subjects (although significantly higher than the ones of narcoleptic patients). Sleep disorders in humans with PWS are multifaceted and are often the result of different mechanisms. Since hypothalamic dysfunction seems to partially influence metabolic, respiratory and sleep/wake characteristics of this syndrome, additional studies are required in this framework.

Long-term effects of growth hormone therapy on patients with Prader-Willi syndrome

AIM

To assess the effects of recombinant human growth hormone (rhGH) treatment in children with Prader-Willi syndrome.

DESIGN

A 1-year study and an observational follow-up visit 10 years later.

METHODS

In 20 patients with Prader-Willi syndrome (PWS): clinical assessment, laboratory tests, body composition analysis by dual energy X-ray absorptiometry, sleep polygraphy, health-related quality of life assessed by 16D.

RESULTS

Only two patients had normal growth hormone secretion at baseline. All patients were significantly shorter than their expected heights, but experienced catch-up growth during growth hormone treatment. At follow-up, 13 patients had reached adult heights and were markedly taller than historical controls. The cumulative dose of rhGH over 10 years correlated inversely with the total body fat percentage (p = 0.033). However, patients remained severely obese at 10 years. Sleep polygraphy was abnormal in more than half of the patients. Health-related quality of life of the patients remained substantially below that of normal population.

CONCLUSION

Growth hormone markedly improved adult height in subjects with PWS when compared to historical data. The cumulative dose of growth hormone correlated with reduction in body fat; nevertheless, patients remained severely obese.