Hiya,
I know you posted this a long time ago, but you might still be interested, so here goes...
I think what you're referring to is vitiligo, a condition in which the pigment in the skin is gradually lost, resulting in pale patches. It's quite common, and the tendency runs in families, but it is unusual for a child to be born with it - it usually develops later in life. Some people think this is what Michael Jackson has, although I don't think he's ever said so definitely. It can affect people of any race, but obviously it's more noticeable on dark skin.
Partial albinism, on the other hand, is a different condition, in which someone is actually born with these paler patches on their skin, giving them a spotted or speckled appearance. They usually also have a characteristic white streak of hair at the front. Partial albinism is rare.
(I know about this because I'm an artist currently doing a project based on recorded cases of partial albinism in the 18th and early 19th centuries. Black people with the condition - most of them slaves - were sometimes exhibited as 'marvels' or 'prodigies' (basically, a freak show.) If you google George Alexander Gratton or Mary Sabina, you can find out about 2 well-known cases. The Hunterian Museum in London will soon be running an exhibition about partial albinism - I don't know where you're based, but if you're in London it should be worth a look.
cheers
