No gene or group of genes has been proven to cause lupus. Lupus does, however, appear in certain families, and when one of two identical twins has lupus, there is an increased chance that the other twin will also develop the disease. These findings, as well as others, strongly suggest that genes are involved in the development of lupus. Although lupus can develop in people with no family history of lupus, there are likely to be other autoimmune diseases in some family members. Certain ethnic groups (people of African, Asian, Hispanic/Latino, Native American, Native Hawaiian, or Pacific Island descent) have a greater risk of developing lupus, which may be related to genes they have in common.
While a person’s genes may increase the chance that he or she will develop lupus, it takes some kind of environmental trigger to set off the illness or to bring on a flare. Examples include:
* ultraviolet rays from the sun
* ultraviolet rays from fluorescent light bulbs
* sulfa drugs, which make a person more sensitive to the sun, such as: Bactrim® and Septra® (trimethoprim-sulfamethoxazole); sulfisoxazole (Gantrisin®); tolbutamide (Orinase®); sulfasalazine (Azulfidine®); diuretics
* sun-sensitizing tetracycline drugs such as minocycline (Minocin®)
* penicillin or other antibiotic drugs such as: amoxicillin (Amoxil®); ampicillin (Ampicillin Sodium ADD-Vantage®); cloxacillin (Cloxapen®)
* an infection
* a cold or a viral illness
* an injury
* emotional stress, such as a divorce, illness, death in the family, or other life complications
* anything that causes stress to the body, such as surgery, physical harm, pregnancy, or giving birth
Although many seemingly unrelated factors can trigger the onset of lupus in a susceptible person, scientists have noted some common features among many people who have lupus, including:
* exposure to the sun * an infection * being pregnant * giving birth * a drug taken to treat an illness
However, many people cannot remember or identify any specific factor that occurred before they were diagnosed with lupus.
Hormones are the body’s messengers and they regulate many of the body’s functions. In particular, the sex hormone estrogen plays a role in lupus. Men and women both produce estrogen, but estrogen production is much greater in females. Many women have more lupus symptoms before menstrual periods and/or during pregnancy, when estrogen production is high. This may indicate that estrogen somehow regulates the severity of lupus. However, it does not mean that estrogen, or any other hormone for that matter, causes lupus.