>A young woman is brought to the hospital with a frightening array of problems, any one of which could be fatal. Her kidneys and heart are barely functioning. She is having difficulty breathing and her skin is covered with purplish blotches. On top of all this, she seems mentally confused and may have had a stroke.

At first, the doctors are stumped. Fearing some kind of virulent infection or poisoning, which might have caused these symptoms, they give the young woman antibiotics and dialysis treatment to aid her failing kidneys. Unfortunately, in this woman's case, the cause was neither infection nor poisoning but, instead, a rare and mysterious illness called CAPS, catastrophic antiphospholipid antibody syndrome.

CAPS causes the blood's clotting mechanism to go haywire, blocking blood flow to organs throughout the body. Antibiotics and dialysis will do little good. Unless the patient's doctors realize that they are dealing with CAPS, the young woman will probably not receive the high doses of immunosuppressive and anticoagulant drugs she needs.

The best feature of CAPS is that is exceedingly rare. Though still a mystery, CAPS seems to be a more dangerous cousin of a condition called antiphospholipid syndrome or APLS. Like CAPS, APLS causes over-coagulation of the blood, that is too much clotting, which leads to arterial blockages, blood platelet production problems, and, in pregnant women, spontaneous abortion.

We don't know what causes APLS or CAPS. One clue suggests that both diseases may involve an underlying immune disorder because APLS usually occurs in people who also have SLE (lupus). But even this relationship is not definite since APLS also occurs in people without lupus or other connective tissue disease. And we have seen, too, that CAPS can attack people with no previous diagnosis of APLS or of SLE.

Like many autoimmune disorders, where the body makes antibodies against itself, CAPS is more common in females, by approximately 2:1. The typical victim is a young adult, although it can affect people of any age. In about one-fifth of those who come down with CAPS, there is a triggering factor -- some illness or event that seems somehow associated with the beginning of the disease. The most common triggering factors are infections, drugs (especially anticoagulants), minor surgical procedures and hysterectomy. Late term pregnancy may also be a trigger.

The kidney is the most common target. CAPS sufferers often arrive at the hospital with serious kidney symptoms such as low or non-existent urine production and high blood pressure. These are caused by a cutoff of blood flow to the kidneys.

CAPS often causes significant deterioration in brain function, ranging from confusion to coma. Some victims experience seizures or even blindness. Unexplained changes in behavior and emotional instability are common. Like the kidney problems, these symptoms are caused by a sudden cutoff of blood flow to parts of the brain.

Approximately 25% of reported cases of CAPS involve labored breathing and a nonproductive cough. The symptoms are similar to those of adult respiratory distress syndrome (ARDS).

People with CAPS may develop acute left ventricular failure (the heart can't pump blood efficiently), caused by blockages in the smaller arteries around the heart, as well as accelerated hypertension and cerebral hemorrhaging.