Dear alessia,
these website will give you some information
Ehlers-Danlos National Foundation - Home
Ehlers Danlos Support Group - Home Ehlers Danlos Syndrome - encyclopedia article about Ehlers Danlos Syndrome.
I can also recommend this article.
Pediatric Generalized Joint Hypermobility With and Without Musculoskeletal Complaints: A Localized or Systemic Disorder? -- Engelbert et al. 111 (3): e248 -- Pediatrics The first author has specialized in this field. He has published more.
good luck
esther