(Using this idea, but expanding upon it since the thread seems a little dead ^^)

We have a few mane mutations, so why not coat mutations? Specifically, a curly coat.

This mutation has been seen in felines (domestic) and has been bred to produce unique breeds that accentuate these mutations. Domesticated cats have three types of hair structures in their coat-- Guard hairs (straight and stiff, provides insulation), awn hairs (usually thicker and softer than guard hair), and down hairs (short, soft, very fine). To achieve a curly coat, the cats must have missing or altered versions of the typical coat layers.

Different altercations to the coat produce different curly coats, which in turn has produced different breeds that have them, which is generally called the 'Rex' coat:

The Cornish Rex
Cornish Rex's are born with just the soft, fine down hairs, thus producing a wavy, rippled appearance. This feline does not do well in heat or cold, as they are very unable to control their body temperature with only one type of coat, and therfore must reman indoor compainions.

Devon Rex
This breed has a very sparse to almost non existent topcat, and are prone to bald patches. Because of this, the have a rather frail and fragile appearance.

Oregon Rex
Coat is silky, short and tight, with no or very short guard hair.

LaPerm
Coats have a soft, tousled look, and might include tight curls.

Selkirk Rex
This feline has a loose curl throughout it's coat, in the whiskers. Their kittens are seriously the most adorable things I have ever seen.

We can assume a lion's coat is at least similar to a housecat's, as it has its uses in protecting the animal from temperature changes and elements; therefore it's possible that these mutations could exist, in theory (I really couldn't find any information on a lion's coat anatomy, if anyone else can, that'd be helpful!).

Continuing with that assumption, there could potentially be five different curly coat mutations, which have chances of passing down when bred (could possibly be a MoD: Curly Fur with chances at getting one of the five mutations):

Cornish: A wavy, rippled coat.

Devon: sparse coat, almost sphinx like appreance, with bald patches appearing as the lion ages.

Oregon: Short, dense, silky.

LaPurm: Tight curls, "gypsy" look.

Selkik: Fine, loose curls, curled whiskers. If male, curls would affect mane. Cubs would look adorable.

If not created as an MoD, some of these could possibly be a lethal at any age, as the lion would overheat or dreeze due to being unable to control it's body temperature properly.