Dictionary

private mutation A rare gene mutation that is usually found only in a single family or a small population. A private mutation occurs and is passed to a few family members, but not to future generations.

prehypertension A precursor state to high blood pressure (hypertension) in which the systolic pressure is between 120 and 139 mm Hg or the diastolic pressure is between 80 and 89 mm Hg. Lifestyle changes are recommended for anyone with prehypertension. See also high blood pressure.

preleukemia See myelodysplastic syndrome.

premalignant Pertaining to tissue that is not yet malignant but is poised to become malignant. Appropriate clinical and laboratory studies are designed to detect premalignant tissue while it is still in a premalignant stage. A battery of techniques are available to remove or kill the tissue, thereby preventing the development of cancer. The proper treatment…

premature aging disorder A condition that causes a person to appear far older than their actual age. See progeria; Werner syndrome.

premature baby A baby who is born before 37 weeks of gestation have passed since the mother’s last menstrual period. A premature baby who is born very close to its due date may suffer few, if any, consequences. The earlier in development that birth takes place, the greater the likelihood that life-support systems will be…

premature birth Birth before 37 weeks of gestation have passed. Premature birth carries increased risks the farther it occurs from the 37-week goal. Many procedures are available to prevent premature birth, from bed rest to medications. If premature birth is medically necessary or inevitable, however, it may be accomplished via C-section to limit stress on…

premature contraction of the heart A single heartbeat that occurs earlier than normal. This phenomenon can be within normal limits, or it may represent a medically significant arrhythmia.

premature ejaculation Ejecting semen from the penis, usually accompanied by orgasm, occurring sooner than a man wants during sexual activity. Premature ejaculation is characterized by a lack of voluntary control over ejaculation that interferes with optimal sexual or psychological well-being in either partner.

premature ventricular contraction Contraction of the lower chambers of the heart, the ventricles, that occurs earlier than usual because of abnormal electrical activity of the ventricles. Abbreviated PVC. The premature contraction is followed by a pause as the heart’s electrical system resets itself; the contraction following the pause is usually more forceful than normal. These…

premenstrual dysphoric disorder An unusually severe form of premenstrual syndrome characterized by drastic mood swings, anger, depression, irritability, tension, sleep and appetite changes, fatigue, and physical problems such as pain or bloating. Abbreviated PMDD. Symptoms generally begin the week before menstruation and end a few days after menstruation has begun. Treatment can involve the use…

premenstrual syndrome A combination of physical and mood disturbances that occur in the last half of a woman’s menstrual cycle, after ovulation, and normally end with the onset of the menstrual flow. Abbreviated PMS. Physical features of PMS include breast tenderness and bloating. Psychological changes can include anger, mood changes, and depression. The most helpful…