vsd

this means :ventricular septal defect, this is a disease in which there is a hole between two ventricles in the heart.
last week i tested the hearts of pupils in a school and i discovered that a little girl has vsd , her mother came to me weeping that her daughter has a defect in her heart , i felt both happy and guilty as i discovered a defect which will be treated early , and sad as i caused the mother sad and weeping .
the little poor innocent girl will live her life in danger , she will be in danger when she plays , marries and during pregnancy and labour.
i always wondred about congenital heart diseases and other congenital defects , why god creates such defects which cause disasters in poeple s life? this is complete evil, evil in the world says that god may not exist, evil contradicts with god mercy and grace, pl god tell me really why did u create VSD?