Overview
Obesity due to melanocortin 4 receptor deficiency, also called MC4R deficiency or MC4R-associated obesity, is a rare genetic condition that causes severe obesity starting in early childhood. It happens when a gene called MC4R does not work properly. This gene makes a protein in the brain that helps control hunger and how the body uses energy. When this protein is missing or not working well, the brain cannot send the right signals to stop eating, so a person feels hungry almost all the time and gains weight very easily. People with MC4R deficiency tend to gain weight rapidly in the first few years of life. They often feel intense, constant hunger that is very hard to control, even after eating a full meal. Along with obesity, many people develop related health problems like type 2 diabetes, high blood pressure, and joint pain. Some people also grow taller than expected during childhood. For a long time, treatment focused mainly on diet, exercise, and behavioral support, but these approaches were often not enough because the hunger drive is driven by a brain-level problem. A newer medication called setmelanotide (brand name Imcivree) has been approved specifically for MC4R deficiency and works by targeting the same brain pathway that is affected. This has been a major step forward for patients and families dealing with this condition.
Also known as:
Key symptoms:
Severe, hard-to-control hunger (hyperphagia) starting in early childhoodRapid and significant weight gain beginning in infancy or toddler yearsObesity that is much more severe than typical childhood obesityFeeling hungry again very soon after eating a full mealTaller-than-average height during childhoodType 2 diabetes or high blood sugarHigh blood pressureHigh cholesterol or abnormal blood fatsJoint pain and mobility problems due to excess weightSleep apnea or breathing problems during sleepLow energy and fatigueEmotional distress, low self-esteem, and social difficulties related to weight
Clinical phenotype terms (10)— hover any for plain English
Autosomal dominant
Passed on from just one parent; each child has about a 50% chance of inheriting it
Childhood
Begins in childhood, roughly ages 1 to 12
Treatments
No FDA-approved treatments are currently listed for Obesity due to melanocortin 4 receptor deficiency.
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Specialists
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Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Obesity due to melanocortin 4 receptor deficiency.
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
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Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.Is my child a good candidate for setmelanotide, and what results should we realistically expect?,Which other genes should be tested alongside MC4R to make sure we have the right diagnosis?,What specialists should be part of my child's care team, and how often should we see each one?,What are the most important health complications to watch for, and how do we screen for them?,Are there any clinical trials or new treatments we should know about?,How should we talk to our child's school about their condition and their needs?,Since this condition can run in families, should other family members be tested?
Common questions about Obesity due to melanocortin 4 receptor deficiency
What is Obesity due to melanocortin 4 receptor deficiency?
Obesity due to melanocortin 4 receptor deficiency, also called MC4R deficiency or MC4R-associated obesity, is a rare genetic condition that causes severe obesity starting in early childhood. It happens when a gene called MC4R does not work properly. This gene makes a protein in the brain that helps control hunger and how the body uses energy. When this protein is missing or not working well, the brain cannot send the right signals to stop eating, so a person feels hungry almost all the time and gains weight very easily. People with MC4R deficiency tend to gain weight rapidly in the first few
How is Obesity due to melanocortin 4 receptor deficiency inherited?
Obesity due to melanocortin 4 receptor deficiency follows a autosomal dominant inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Obesity due to melanocortin 4 receptor deficiency typically begin?
Typical onset of Obesity due to melanocortin 4 receptor deficiency is childhood. Age of onset can vary across affected individuals.