Tetra-amelia syndrome

Tetra-amelia syndrome (sometimes known as TETAMS) is a very rare disorder characterized by the absence of all four limbs. ("Tetra" is the Greek word for "four," and "amelia" refers to the failure of an arm or leg to develop before birth.)  

This syndrome can also cause severe malformations of other parts of the body, including the nervous system, face, head, heart, skeleton, gastrointestinal system, urinary tract, and genitalia. The lungs are underdeveloped in many cases, which makes breathing difficult or impossible. Because children with tetra-amelia syndrome have such serious medical problems, most are stillborn or die shortly after birth. 

There are two forms of tetra-amelia syndrome that have been described, and while the features overlap, they are distinguished by their signs and symptoms and genetic cause. 

Tetra-amelia syndrome type 1 is typically characterized by severe gastrointestinal problems. These problems include an opening in the abdomen through which various abdominal organs can protrude(abdominal wall defect), abnormalities in the muscle (diaphragm) that separates the organs in the abdomen from those in the chest, and lack of an anal opening (imperforate anus). People with type 1 also tend to have frequent urinary tract problems, such as a lack of kidney development (renal agenesis). 

Tetra-amelia syndrome type 2 is usually characterized by complete absence of both lungs. Affected individuals often have heart abnormalities, such as defects in the walls between the chambers of the heart (septal defects) or absence of the mitral valve, which connects the two left chambers of the heart. People with type 2 can also have facial abnormalities that include partial or complete fusion of the upper and lower eyelids, the bottom of the tongue attached to the floor of the mouth, or a small lower jaw (micrognathia).