I was curious as to what kind of development abnormalities that have occurred and this is what I found:
First of all, down syndrome is the most common chromosomal abnormality affecting 1 in 800 babies. The chances of this happening increases as the mother ages. The problem is due to an extra 21 chromosome. This leads to an over expression of those genes.
Another one that I came across is called harlequin-type ichthyosis. This is a skin disease characterized by thickening of the keratin layer in fetal human skin. What happens in the the skin contains massive, diamond-shaped scales that tend to be a reddish color. Besides that, the ears may be very poorly developed or absent entirely, same for the nose. The eyelids everted, and often bleed upon birth. the lips are fixed into a wide grimace. Arms, feet and fingers are always always deformed in that they cannot bend properly, and may be below the normal size. Because of the skin condition, it easily cracks causing an increased risk of bacterial infection. This disease is associated with a mutation in the gene for the protein ABCA12. This protein is called ATP-binding cassette transporter 12. This protein is essential for normal development of the skin. It is thought to be important for transporting lipids in cells that make up the epidermis of the skin.
Here are a few more brief genetic accidents that I came across:
Frog-like baby: In 2006, a baby was born that was neck-less. The head was almost totally sunk into the upper part of the body. Also, the eyeballs were extremely large and literally popping out of the eye-sockets. Unfortunately, the baby died within a half hour after birth.
13-inch tailed man: from a congenital defect, this man has a tail. It is located in the coccygeal end of the vertebral column, and he would not survive without it.
Cyclop Baby: In 2006, this baby was born with one eye. The medical staff believe that it was due to an experimental anti-cancer drug or from a chromosomal disorder known as cyclopia. The baby was born with a one eye in the center of her forehead, with no nose, and her brain was fused into one hemisphere. The baby was able to survive for a few days, but then, unfortunately, pasted away.
Feet facing backwards: A women in China was born with her feet facing the wrong way.
Baby with Three Arms: In 2006, a baby was born with a third arm. The arm was successfully removed, but the baby will need a long-term physical therapy to gain function in the remaining hand. That hand has no palm and flexes in either direction.
Nipple on the foot: A 22-year old women sought medical care to get a well-formed nipple surrounded by areola and hair removed from her the plantar region of her foot. Microscopic examination of the dermis showed hair follicles, eccrine glands, and sebaceous glands, alone with fat tissue on the base.
With all of these abnormalities, I am curious as to if we will ever find answers to why these happen. I am sure with how much we have discovered so far that eventually we will have out answers. However, the conditions seem so complicated that it will most likely take years and years to get to a conclusion.