Early in the evening of June 25, 1995, hours after the birth of his first and only child, the course of Dr. Alberto Costa’s life and work took an abrupt turn. Still recovering from a traumatic delivery that required an emergency Caesarean section, Costa’s wife, Daisy, lay in bed, groggy from sedation. Into their dimly lighted room at Methodist Hospital in Houston walked the clinical geneticist. He took Costa aside to deliver some unfortunate news. The baby girl, he said, appeared to have Down syndrome, the most common genetic cause of cognitive disabilities, or what used to be called “mental retardation.”
Costa, himself a physician and neuroscientist, had only a basic knowledge of Down syndrome. Yet there in the hospital room, he debated the diagnosis with the geneticist. The baby’s heart did not have any of the defects often associated with Down syndrome, he argued, and her head circumference was normal. She just didn’t look like a typical Down syndrome baby. And after all, it would take a couple weeks before a definitive examination would show whether she had been born with three copies of all or most of the genes on the 21st chromosome, instead of the usual two.
Costa had dreamed that a child of his might grow up to become a mathematician. He had even prevailed upon Daisy to name their daughter Tyche, after the Greek goddess of fortune or chance, and in honor of the Renaissance astronomer Tycho Brahe. Now he asked the geneticist what the chances were that Tyche (pronounced Tishy) really had Down syndrome.
“In my experience,” he said, “close to a hundred percent.”