In one of those "I have been diagnosed with this disease you haven't heard of before, and also I am a celebrity" stories in People magazine, Missy Elliott revealed part of the reason why she's had such a low profile in the six years since her last album: She's been diagnosed with Grave's disease, an autoimmune disorder that affects the thyroid and causes weight loss and mood swings. Elliott was diagnosed with the disease in 2008, and has only just now gotten it under control: She has lost a lot of weight, and she is back in the studio with Timbaland. Elliott will tell people about her disease on the June 29 episode of Behind the Music, which is back on, apparently. Read some stuff about Elliott's People profile at Billboard.
Update: Here's the official statment from Missy Elliott given on June 24, 2011.
“There have been some inaccuracies reported in regards to my diagnosis with Grave’s Disease, so I wanted to clear things up. I was diagnosed with Grave’s Disease about three years ago but it really hasn’t slowed me down at all. I rocked my performance on VH1 Hip Hop Honors’ tribute to Timbaland last year. I’ve written and produced a bunch of Grammy-nominated, #1 hits for artists like Keyshia Cole, Monica and Jasmine Sullivan. I toured the UK, Europe, Asia, Africa and Australia. And on top of all that, I’m working on my new album. I feel great. Under my doctor’s supervision, I’ve been off medication for about a year and I’m completely managing the condition through diet and exercise.”