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Welcome to path4HCPs
Here you can learn more about rare melanocortin-4 receptor (MC4R) pathway diseases, their diagnosis and management.
Rare MC4R pathway diseases can be caused by genetic variants within the pathway (part of the central melanocortin pathway). These changes can impair signalling in the pathway that controls hunger and can be a root cause of increased appetite and body weight.1
To accurately diagnose and care for those possibly living with a rare MC4R pathway disease, it is crucial to undertake a detailed observation of the patient and gain confirmation of any underlying genetic cause.
A proper understanding of a root cause of the disease allows for appropriate management and care of patients.1
Here you can find information about rare MC4R pathway diseases, including:

Bardet-Biedl syndrome
Bardet-Biedl syndrome (BBS) is a rare ciliopathy, resulting from genetic variants within the BBS family of genes. This heterogeneous genetic disease presents with a variety of symptoms that can evolve over time, including:2,3
- Cognitive impairment
- Early-onset, severe obesity
- Genital anomalies
- Hyperphagia
- Polydactyly
- Renal disease
- Visual impairments
Diagnosis of BBS is based on clinical findings; diagnosis confirmed by genetic testing.3

Pro-opiomelanocortin deficiency and leptin receptor deficiency
Pro-opiomelanocortin (POMC) and leptin receptor (LEPR) deficiencies are genetically identifiable rare MC4R pathway diseases (known as monogenic obesity). They are autosomal recessive inherited diseases caused by variants in the POMC or LEPR gene. Diagnosis of POMC and LEPR deficiency may be suspected based on clinical manifestations, such as hyperphagia and early-onset obesity, and is confirmed by genetic testing.2
Latest videos

56 mins
How to identify genetic causes of obesity and related syndromes. Understanding the role of the MC4R pathway in monogenic obesity and Bardet-Biedl syndrome

74 mins
Hyperphagia and early-onset, severe obesity: What does good multidisciplinary team (MDT) care look like for patients living with MC4R pathway diseases?