In thousands of laboratories throughout our country researchers have dedicated their careers to finding a cure for everyone's ailing child, for every suffering adult. Their dedication is great, their compassion strong, but their work cannot move forward without the help of many other caring individuals.      Human tissue donated at the time of death by people of all ages, especially those afflicted with a genetic or developmental disorder, is the most precious resource on which these researchers depend. It is in human tissues, particularly the brain, that many of these dysfunctions occur and manifest themselves. By examining these tissues, comparing the unaffected with the affected, or by comparing different age groups, scientists begin to answer endless questions. As answers unfold so will deeper understanding, offering hope to the lives of us all.