The severely obese patient - a genetic work-up

Background A 6-year-old boy weighing 53 kg was referred to a specialist unit for investigation of severe obesity. Parental reports of persistent severe hyperphagia and food-seeking behavior from a very early age raised the possibility of a genetic obesity syndrome. The family history was suggestive of a dominantly inherited condition, because the boy's father had been hospitalized in early childhood for the management of his obesity. Investigations Physical examination of the patient, and his mother and father, measurement of serum leptin and insulin levels, lipid profile and thyroid function tests, karyotyping and molecular genetic testing. Diagnosis The patient was heterozygous for a missense mutation in the melanocortin 4 receptor gene, which segregated in a dominant manner in this family. Management Counseling for genetic studies in the family and advice regarding dietary management.