The blame for mankind's sicknesses/diseases and consequent death has been placed squarely on the shoulders of Adam:
Romans 5:12, 17 - 19:
"Therefore, just as sin entered the world through one man, and death through sin, and in this way death came to all people, because all sinned—
For if, by the trespass of the one man, death reigned through that one man.......
Consequently, just as one trespass resulted in condemnation for all people........
For just as through the disobedience of the one man the many were made sinners........"
1 Corinthians 15: 21, 22:
"For since death came through a man........... For as in Adam all die......."
But was it Adam (and Eve) who altered his own DNA/genetic makeup so that sicknesses/diseases and consequent death would be passed on to his offspring or was it God who did this?
It is not a part of JW doctrine/practices to pray for healing but there are Christians who do this as it is a part of their doctrine/practices. I find it ironic that such Christians pray for healing from sicknesses/diseases when it is in fact God who altered Adam's (and Eve's) DNA so that his offspring would become sick and die in the first place - that is, it is God who made them prone to sickness yet they are praying to him for healing.
The implication of all of this is that since it is God who altered Adam's (and Eve's) DNA so that his offspring would become sick and die, then God is responsible for the sicknesses/diseases and the consequent death and suffering in the world.