I have a new grandson, born just after Thanksgiving, who has Down Syndrome. He’s having open-heart surgery tomorrow to correct a defect that would kill him otherwise.
I’ve looked up everything I can about the condition, and one of the questions that remains in my mind is exactly how the specific genes on chromosome 21 cause the various symptoms. For example, this site lists the specific genes and what each one does, but I can’t see why any of these would cause things like a heart defect, or a characteristic eye shape, or any of the other typical symptoms.
I’m hoping that among the teeming millions there is someone who knows, or who can point me toward, an explanation.