Infants do not survive long after birth. Mental development is absent. Cranial development is suppressed. Microcephalic - Very uncommon. Grossly mentally retarded.
Brain is severely underdeveloped.
Cause uncertain, but may be a trisomy of the autosomes. Environmental factors possible. Amelia - No arms or legs, many other problems too. Acephalia - No head. Tubal Pregnancy - Occurs when a zygote implants in the walls of the fallopian tubes.