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| Common Disorders | |||||||
Prader Willi Syndrome Prader Willi Syndrome is a genetic disorder caused by a deletion of part of the paternal chromosome 15 in the majority of cases, although it can also be caused by an anomaly on the same chromosome coming from the mother. Angelman syndrome is also caused by an abnormality of the same chromosome but usually the maternal one. These two diseases are example of a genetic mechanism called imprinting, where genes are expressed differentially based upon the parent of origin. The first reports came from Prader et al in a series of patients in 1956 and in 1981; Ledbetter et al identified microdeletions within chromosome 15 as the site for PWS. Different prevalence rates have been reported ranging from 1 per 16,062 to 1 in 25,000. PWS is a complex multisystemic disorder characterized by hypotonia, developmental delays, short stature, hypogonadism, behavioral abnormalities, hyperphagia and obesity. This syndrome requires a multidisciplinary approach in order to understand and appropriately treat all the different conditions that are encompassed in the syndrome. Even though every patient is a different case in general patients diagnosed with Prader Willi Syndrome should be studied for these next components of the syndrome: - Genetic testing for PWS including chromosome analysis to establish the cause of the syndrome. - An endocrinology consult is important in order to study pituitary dysfunction including growth hormone deficiency, short stature, central obesity, osteoporosis, hypogonadism, assessment of thyroid and adrenals can be also performed - Nutrition orientation and obesity complications should be evaluated, screening for type II diabetes mellitus and other biochemical problems. - Psychiatry/Psychology evaluations for the management of behavioral problems. - Other important consults: Ophthalmology, Pulmonology. From the orthopaedic point of view, PWS patients should be assessed by a pediatric orthopaedic surgeon in order to rule out any of the different musculoskeletal manifestations they can present. Different studies have reported high incidence of ligamentous hyper laxity, hypotonia, flat feet, and delayed bone age which are to be observed by the orthopedist. Some other important skeletal problems have a higher incidence in PWS patient’s than in the general population: scoliosis and kyphosis (abnormal spinal curvature), hip dysplasia and lower extremities alterations ( knock knees, leg length discrepancy) are commonly seen and can be properly addressed by an experienced orthopaedic surgeon. Scoliosis is one of the main problems we treat on patients with Prader Willi, spinal curves in these patients usually progress during adolescence, close observation and x-ray screening must be done during this period of time and anytime when spine asymmetry is encountered. The relationship between growth hormone (GH) for the treatment of PWS patients and progression of spinal curves is still not clear but recent studies have shown that the curves do not increase in size more when the patients are taking GH. Various studies have shown the differences between PWS patients and healthy children with scoliosis, clear differences in the risks and complications with these patients have been found. Their associated obesity and hypotonia magnify the musculoskeletal problems and proper preoperative dietary management is a main stem of treatment. Some other surgical and anesthetic concerns will be appreciated by the treating physician for each particular case. Hip disease is also common among Prader Willi Syndrome patients; developmental dysplasia of the hip (DDH) has been reported to be even 10 times more common in patients with the syndrome. The high incidence could be consequence of hypotonia and ligamentous laxity, which allow the head of the femur to be misplaced. Delay in diagnosis and subsequent development of degenerative joint disease must be avoided, an early consult with an orthopaedic surgeon will rule out this problem and avoid the catastrophic consequences. Although the diagnosis and treatment of hip dysplasia in patients with PWS has not been formally studied, it is clear that early detection and treatment improves long-term results. Prader Willi is a risk factor for DDH therefore this division recommends early screening x-rays even in the asymptomatic patient. . Other lower extremity problems are also present and should be addressed; flat feet, cavus feet, knock knees and leg length inequality have all been reported in PWS patients. Slipped Capital Femoral Epiphysis (SCFE) which is a common pathology in obese children, is not more frequent in PWS according to the most recent studies. Usually all of these abnormalities can be treated in the mild cases with braces or orthosis but when they become severe operative treatment can be beneficial for the patients.
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