Good question. About about 8 million babies worldwide are born with gene-related birth defects.
Some of the more common ones include
Down Syndrome
Thalassemia
Heart defects:
G6PD deficiency
Sickle cell disease
spina bifida
Good nutrition, family planning, and appropriate medical care are simple steps to avoid birth defects. Others include fortifying salt with iodine to cut down on illnesses due to insufficient iodine. Fortifying flour and other grain products with folic acid (folate) to help avoid neural tube birth defects.