Genetic factors certainly have a strong influence on the energy homeostasis, but a few genetic oligogenic and monogenic syndromes were already identidied associated to the obese state. Among them, we can find mutations of the leptin receptor, that have been found in patients with severe obesity of early onset. The prevalence of these mutations were not systematically studied. LEPR is located on chromosome 1 (1p31), and it codifies a 1172-aminoacid protein that is predominantly expressed in hypothalamus. Homozygote LEPR mutations were reported leading to severe obesity and pituitary disorders, beyond disturbed eating behavior similar to to Prader-Willi patients behavior. Other mutations were reported in 3% of severe obese patients of early onset with hyperphagic eating pattern and leptin levels similar to the levels found in patients without mutation. There are no leptin gene mutation studies in the Brazilian population. The aim of this study is to analyze the LEPR exonic region in 25 adults and children with severe obesity of early onset, with BMI Z score > +2,8. Patients will be submitted to complete physical examination, biochemical and hormonal evaluation and bone age. The molecular study will be performed according to the following: peripheral blood DNA extraction, amplification of the exonic and boundering intronic regions by polymerase chain reaction (PCR). PCR products will be submitted to automatic sequencing.
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