Three causes of rare sense disorder as Little Mix star reveals life altering diagnosis

Living without one of your five senses can affect almost every aspect of your day to day life and, as Little Mix's Perrie Edwards revealed recently, can cause you to miss important signs in dangerous situations.

The pop star found out that she had been born without a sense of smell at the worst possible time, when a fire began to tear through her childhood home. Perrie only noticed when black smoke started to fill the room and she struggled to breathe, reports the Mirror.

This rare health condition is called congenital anosmia, a birth defect experienced by one in every 10,000 Brits. According to sensory charity Fifth Sense, most people do not even notice they are missing this sense until they reach the middle of their childhood and someone points it out at school - but it can have a variety of causes.

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With many people born without the ability to smell noticing the condition in childhood, it can often be an early warning sign of a more serious problem that could affect their adolescence. Called Kallmann Syndrome, anosmia can be caused by a problem with your hypothalamus, which is involved in the production of the sex hormones that trigger puberty.

Losing your sense of smell is one of the tell-tale signs of the syndrome, distinguishing it from other puberty-inhibiting medical problems. Though it can cause infertility, doctors can treat it with hormone replacement therapy.

Another strange cause for being born without a sense of smell is congenital pain insensitivity, a rare condition that causes someone's brain to incorrectly process pain signals. People with this disorder can easily damage themselves, with many unable to even sense heat.

Fifth Sense explained: "Many people with congenital insensitivity to pain also have a complete loss of the sense of smell because the same channels that transmit messages of pain from the pain site to the brain can affect the channels in the olfactory sensory neurons that transmit messages of smell signals to the brain."

As you can imagine, when someone is born without the ability to feel pain, their lack of ability to smell can be overlooked, but people with this difficult condition will often also report a lack of a sense of taste - a common side effect of losing your sense of smell.

The third most common cause of anosmia is also the least complicated, and the kind that Perrie Edwards was diagnosed with after her family home caught alight, isolated congenital anosmia.

This defect in your sense of smell has no other symptoms, which can cause people to not even notice they have it. Rather than being caused by an issue in your brain, this anosmia is caused by a defect in the olfactory receptors in your nose - which convert particles in your nose into an electrical signal that your brain converts to a particular smell.

There are few effective treatments for this, something Perrie Edwards discovered. She said: "I had surgery, came out, had big tampons in my nose, recovered for a while. And then I swear to God I could smell coffee. I woke up and smelled the coffee.”

But her sense of smell left again soon after and Perrie decided to keep on living without it, saying: “I was like, I'm not going through that again. I don't care. If I had it and lost it, fair enough. But I've never had it, so why care?”