A 19-Year-Old Man With Life-Threatening Obesity

Shahida Badsha, MBBS, FCPS, MCPS


April 09, 2018


The pathophysiologic basis of different diseases that lead to obesity differs and requires different approaches to diagnosis and management. In addition to metabolic studies, genetic studies are often required to support the correct diagnosis. Exogenous or common obesity has a multifactorial etiology with a polygenic basis. Although no consensus has been established regarding the definition of morbid obesity, a BMI >3 standard deviations for age is considered an acceptable parameter.[1] The patient in this case had a medical history and clinical features suggestive of Prader-Willi syndrome. His history of excessive food intake and past treatment with steroids for his dermatitis may have misled physicians to a diagnosis of either exogenous obesity or iatrogenic Cushing syndrome. The diagnosis of Prader-Willi syndrome was based on the clinical features of a voracious appetite, gross obesity with short stature, disproportionately small hands and feet, and no signs of facial, axillary, or pubic hair.

Prader-Willi syndrome is the most common cause of morbid, syndromic obesity, with an estimated worldwide prevalence of 1:10,000 to 1:30,000. Males and females are affected with equal frequency, and the syndrome is seen in all races and ethnicities. It is a genetic disorder primarily caused by gene deletion on the paternal-inherited chromosome 15 in the q11.2-q13 region. Overall, three molecular mechanisms of Prader-Willi syndrome have been described: paternal 15q11.2-q13 deletion, maternal uniparental disomy (UPD) of chromosome 15, and imprinting defect. These mechanisms constitute 65%-75%, 20%-30%, and 1%-3% of cases, respectively. DNA methylation analysis is the technique used to diagnose PWS for all three mechanisms.[2]


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