Mana Deficiency

Edda is an intensely magical place, and even the most basic, untrained, mundane individual has mana flowing through them, providing them access to enhanced abilities or magical talent if they so desired or had avenues to go down to obtain them. 
This makes the seemingly random disease of Mana Deficiency all the more confusing.
Individuals born with Mana Deficiency, also known as Mana Void, have absolutely no detectable mana within their bodies. Their bodily organs work as normal, and it doesn't have an innate effect on those bodily functions in any way, but it renders the individual incapable of utilizing any magical ability. The amount in which their body seems to actively either absorb or negate the very molecular essence of mana is to the point where those afflicted with Mana Void can only be healed by magic at a rate of 50% what a normal individual could do, and they cannot be revived from death by magic. Even using items with mana stored within them, such as wands, scrolls, or grimoires, have a 75% chance of failing in the hands of someone afflicted with Mana Void.
It's currently very difficult to study the potential causes or further effects of Mana Deficiency, as obviously the magical instruments and techniques utilized by most of Edda's medical and scientific practitioners are ineffective on individuals with Mana Deficiency. Practical medicine has been making some breakthroughs, and new techniques are being developed, but there's still very little actually known about the condition.
One of the most well-known victims of Mana Deficiency is the engineering mastermind Marion de Chance, an open and vocal victim of the condition, and her business ethos of relying as little as possible on magic comes from that handicap.

Transmission & Vectors

It is currently unknown how Mana Deficiency transmits, as it's present from birth. Currently, it's not even known if it is a genetic disease, as it affects all sorts of individuals from various different backgrounds.

Symptoms

Victims of Mana Deficiency are unable to cast magic from any source, as even using magical items comes with a heavy failure rate. Furthermore, they only receive half as much of a benefit from the healing and restorative magic as other people do. There is a slight benefit to this, as it also makes them resistant to many magical effects and conditions that would only be caused by a spell or similar arcane spreading, but many would see that as only a minor solace.

Cultural Reception

Many people view those born with Mana Deficiency as an ill omen, as many tend to slowly drain mana from the surroundings as a result of their unique physiology. However, the slow trickle far outweighs the natural regeneration of mana, but since when have facts outweighed superstition?

Type

Magical

Origin

Natural

Cycle

Chronic, Congenital

Rarity

Rare