This marvellous essay by Caitrin Nichol on Down syndrome and families by introduces this lovely Madonna and Child by Italian Rennaissance painter Andrea Mantegna, father of 14 children, one of whom may have had Trisomy 21.
A physician has diagnosed the Child Jesus with T21 as well, despite the protests of the curator of the Boston Museum of Fine Arts.
I agree with the doctor.
HT The New Atlantis
Here's another painting where people with T21 are included.