One of the most common beginner reptiles is the Leopard Gecko, so I think it is very important to mention this morph.
The Enigma Leopard gecko is a dominant morph and is very popular.
Enigma on Leopard Gecko Wiki This is good, basic explanation about the Enigma morph, with a brief explanation near the end about the Enigma syndrome.
The Enigma syndrome is the name given to balance and locomotive issues of Enigma leopard geckos. They have, to varying degrees, difficulty moving, and this often increases due to stimuli. They sometimes have difficulty feeding themselves. Here's a well written article on it:
Enigma Syndrome in Leopard Geckos: An Autosomal Dominant Disorder
A study was done in the UK on Enigma syndrome:
TESS
Always ask about the lineage and health of the parents when looking to buy an Enigma leopard gecko, and don't breed ones with severe symptoms.