This is a difficult question to answer because it is subjective. What one person feels is the worst may not be what someone else does. Also the subject matter is kind of macabre.
One of the worst types of birth defects that I can think of off hand is anencephaly. Anencephaly is, like spina bifida, is a defect in the formation of the neural tube, but in this case the fetus does not develop a brain. They may still retain a brain stem so reflex actions like breathing can still happen, but the part of the brain that allows for consciousness is not there. Invariably these babies do not survive long after birth.
In most cases severe malformation results in spontaneous abortion.
Yes, it will cause birth defect.
No they are not, lord jesus! Stop hating -_-
The Spina Bifida birth defect is autosomal.
The term you are probably looking for is "congenital defect."
No
No
Exists from birth.
Exists from birth.
Down's Syndrome is an example of a birth defect characterized by an abnormality of the chromosome structure.
I have never read she had a birth defect. Her favorite color was purple and died wearing purple shoes.
"Congenital" means present at birth. So, a congenital heart defect is a defect (structural anomaly) that is present at birth. 1 in 100 babies are born with a congenital heart defect.
Your question is not clear. "This part" of what? Are you asking about Spina Bifida or another birth defect? Please clarify your question.