Welcome to MC4r and Me – In this post I hope to explain the MC4r deficiency, or in simple terms the ‘obesity gene’.
Most people don’t know what it is, in fact most doctors don’t know what it is! Every time I tell a doctor I have MC4r (melanocortin 4 receptor), I’m met by a puzzled face, which I then have to explain to a medical professional.
I was diagnosed with the deficiency when I was 18-years-old and the journey to getting that diagnosis is a long one, and definitely a story for another day.
The MC4r deficiency is something I read about a lot, mostly because there is so little research about this gene defect that affects 22 per cent of the population.
Most of the research comes out of the Cambridge Metabolic Clinic, and Professor I. Sadaf Farooqi and her team who study how genetics affect obesity.
I owe a lot to the clinic as it was Professor Farooqi who identified my MC4r gene defect after receiving a sample of my blood when I was 13. She spent five years tracking me down, as I had moved house several times and changed doctors office’s multiple times and finally one of my GP’s told me about the diagnosis and put me in contact with the clinic.
But what is the MC4r deficiency I here you ask? The MC4r gene is key to regulating body weight.
The gene controls a hormone called leptin, which is an indicator of ‘nutritional state’.
When we fast out leptin levels drop which triggers a response in the brain to restore energy levels – basically your brain tells you to go eat some food. However, at the same time leptin inhibits POMC neurons, this inhibits food intake – basically it tells you when to stop eating.
Fairly easy to understand, your brain tells you you’re hungry and then your brain tells you when you’re full.
When you have MC4r deficiency, there is a disruption in the process that blocks the signal in the brain to inhibit food intake – basically you don’t get a message from your brain to tell you to stop eating – so you keep eating resulting in ‘over eating’. Research has shown that the disruption within the MC4r gene demonstrates that this pathway is critical for the control of appetite and body weight.
The main ‘clinical’ feature of MC4r deficiency is hyperphagia, an increased drive to eat as well as an impaired sense of satiety (the ability to feel full after a meal).
Now, just to hammer in the nail experts say that people with this defect are ‘less responsive’ to diet and exercise and theories say that in order to respond to a calorie restricted diet they would need to have an ‘intact leptin-melanoncortin system’ which sadly is the part of the brain that is not working correctly.
That is MC4r deficiency in a nutshell – but there is still so much more to say and I’m here to educate, support and share my journey with you.
MC4r and ME 