SUN-602 Weight Loss After Glucagon-Like Peptide-1 Receptor Agonist Treatment in Childhood Obesity with Diabetes and Cirrhosis Associated with a Homozygous MC4R Mutation
Authors: Klee Philippe , Dirlewanger Mirjam , McLin Valérie , Carminho Maria Teresa , Schwitzgebel Valerie M 
Published: May 2020

Abstract
Background
Mutations in the melanocortin-4 receptor (MC4R) represent the most common cause of monogenic obesity. Treatment options are limited but glucagon-like peptide-1 receptor agonists (GLP-1 RA) may be of use to induce weight loss.
Methods
Exome of the patient was captured using the Agilent SureSelect QXT Human All Exon V5 kit and sequenced on Illumina.
Clinical findings and results
We report obesity-associated diabetes and cirrhosis in a 13-year girl born from consanguineous parents of Afghan origin. Past medical history revealed mild mental retardation and excessive weight gain since infancy. Linear growth was normal. Her father was obese and no diabetes was found in the family. The girl was initially investigated for hoarseness and found to have pulmonary hypertension, later accepted to be secondary to cirrhosis and portal hypertension. Physical examination revealed obesity (BMI 34.9kg/m2) and acanthosis nigricans. Blood exams showed leucopenia and thrombocytopenia without anemia, compatible with portal hypertension. Chest CT revealed important dilatation of the pulmonary arteries, a nodular liver and splenomegaly. Liver biopsy confirmed cirrhosis. An extensive workup including whole exome sequencing identified a homozygous MC4R variant [NM_005912.2 (MC4R): c.63_64del, p.(Tyr21*)], classified as pathogenic according to the ACMG guidelines. Both parents were heterozygous for this variant. An endocrinological workup showed insulin resistance with a HOMA-IR index of 7.27 and diabetes with peak blood glucose of 11.5mmol/l. HbA1c was 5.1% (32mmol/mol). Thyroid tests, leptin, proinsulin levels (3.5pmol/l, n &lt;11.0pmol/l) were normal.
The mutation being homozygous with a predicted complete loss of function (https://www.mc4r.org.uk/), no treatment with a MC4R agonist was tried. At the age of 15 years (BMI 36.0kg/m2), the patient underwent liver transplantation because of progressive portal hypertension and to halt the progression of pulmonary hypertension. At the age of 16 years (BMI 33.2kg/m2, HbA1c 4.9% (30.0 mmol/mol), HOMA-IR 5.3) a treatment with GLP-1 RA (liraglutide) was started at a dosage of 0.6mg and progressively increased to 3mg, in an attempt to induce weight loss, avoid the accumulation of liver fat and to protect the graft. GLP-1 RA is supposed to exerts its effects on appetite independently of the MC4R pathway. 2 months after liraglutide introduction, no side effects, a weight loss of 4kg and a decrease of appetite were observed (BMI 31.6kg/m2, HbA1c 4.5% (26mmol/mol), HOMA-IR 3.14).
Conclusion
Obesity-associated MCR4 mutations, in homozygous state, may lead to diabetes, liver cirrhosis and porto-pulmonary hypertension. Treatment options are scarce, but GLP-1 RA seem to have a rapid, positive effect on weight and metabolic control. Would earlier treatment have prevented progression to end-stage-liver disease and need for liver transplantation?