1094 BöRjeson - Forssman - Lehmann Syndrome: A Rare But Important Cause of Obesity

Background & Aims: Borjeson - Forssman - Lehmann Syndrome (BFLS) is a rare X-linked condition characterized by obesity and developmental delay. Only nineteen unrelated cases of BFLS, with confirmed PHF6 mutations, have been reported since its first description in 1962. The phenotype is better characterized in males with moderate to severe developmental delay, microcephaly and hypogonadism. The phenotype of affected females ranges from normal through to developmental delay with obesity and hypothyroidism. Our aim is to report three cases of BFLS, describe the associated endocrine dysfunction and further delineate the female phenotype. Method: Endocrine and genetic results were reviewed of three patients (2 female and 1 male) with a clinical diagnosis of BFLS. Results: Confirmation of the diagnosis was established in one patient and is pending in the other two. All three have developmental delay. Patient 1 is an obese female (BMI 41 kg/m2) with genetically proven BFLS and pubertal delay, autoimmune hypothyroidism and hypercholesterolaemia. Patient 2 is an obese female (BMI 39kg/m2) with autoimmune hypothyroidism, hyperandrogenism and hypercholesterolaemia. Patient 3 is an obese male (BMI 30 kg/m2) with typical dysmorphic features and pubertal delay. Conclusion: BFLS is an important condition to consider when reviewing patients with obesity and developmental delay. We suspect it is more prevalent than reported in the literature and may be missed particularly in females where the phenotype is poorly characterized. Endocrine abnormalities were seen in all of our patients. Because of the X-linked pattern of inheritance, diagnosis and genetic counselling are important.