Is genetic susceptibility to pre-eclampsia conferred by homozygosity for the same single recessive gene in mother and fetus?

Article Abstract:

Pre-eclampsia is a condition of pregnancy in which the mother develops hypertension (diastolic blood pressure greater than 90 mm Hg) and excess protein in the urine, or proteinuria, (more than 0.25 grams per liter) on at least two separate occasions during the final trimester. The condition disappears shortly after delivery. Six models of genetic inheritance are evaluated in this article to determine the possibility that pre-eclampsia is genetically based. The hypothetical dominant allele causing the disorder is called A; the hypothetical recessive allele is called a. The models include: (1) the maternal recessive gene hypothesis in which the mother must be (a,a) for pre-eclampsia to occur; (2) the shared recessive gene hypothesis, where mother and fetus are both (a,a); (3) the fetal recessive gene hypothesis, in which the fetus must be (a,a); (4) the maternal dominant gene hypothesis, where only the mother is (A,a) or (A,A); (5) the shared dominant gene hypothesis, where mother and fetus must be (A,a) or (A,A); and (6) the fetal dominant gene hypothesis, where only the fetus is (A,a) or (A,A). Predictions of the number of affected individuals generated by each model were compared with actual data from family studies. The model most consistent with the data was the shared recessive gene hypothesis. However, important questions concerning a genetic basis remain unanswered. For example, a pregnancy in which the woman has normal blood pressure seems to protect against pre-eclampsia in later pregnancies, indicating that a protective immunity develops. This is unlikely to be a result of the same recessive gene that causes pre-eclampsia. It is more probable that a genetic factor allows pre-eclampsia to occur or makes its occurrence more likely. The shared recessive gene model is the best working hypothesis at this time. (Consumer Summary produced by Reliance Medical Information, Inc.)

Genetic aspects, Preeclampsia, Pregnancy, Complications of, Pregnancy complications

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Treatment of eclampsia

Article Abstract:

Eclampsia is a complication of pregnancy marked by maternal high blood pressure, swelling, protein in the urine and convulsions. Although eclampsia is rare, it is the most common cause of maternal death, particularly in developing countries. Since the mechanisms of eclampsia and preeclampsia (a similar condition but not accompanied by convulsions) are not well understood, treatment is aimed at reducing blood pressure with antihypertensive agents and controlling seizures with anticonvulsive agents. Diazepam is a tranquilizing agent that controls seizures rapidly. However, some clinicians believe that high doses of diazepam are dangerous to the mother and fetus. Two reports published in the February 1990 issue of the British Journal of Obstetrics and Gynaecology address the issue of anticonvulsant therapy to treat eclampsia. The most common anticonvulsant for the treatment of eclampsia is magnesium sulfate, which seem to reduce irritability in the brain and temporarily reduce blood pressure. However, convulsions persist in 10 percent of the patients treated with magnesium sulphate. In an effort to find a more effective treatment, the anticonvulsant phenytoin, an agent used to treat epilepsy, was given to a small group of patients with preeclampsia. Phenytoin was not beneficial in preventing recurrent convulsions. Research should focus on preventing the development of preeclampsia by correcting abnormalities in the blood coagulation system. A program studying the effects of low doses of aspirin is currently underway. Until more effective treatment alternatives surface, patients should be managed with intravenous diazepam or dihydralazine (an antihypertensive), increased body fluids and prompt delivery. (Consumer Summary produced by Reliance Medical Information, Inc.)

Care and treatment

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Malignant ventricular arrhythmias in eclampsia: a comparison of labetalol with dihydralazine

Article Abstract:

Labetalol may be more effective than dihydralazine for the prevention of ventricular arrhythmia, or irregular heart beat, associated with eclampsia. Eclampsia is the development of convulsions and coma in pregnant women in association with preeclampsia, or hypertension of pregnancy. Among 34 pregnant women with eclampsia, 18 were treated with labetalol and 16 were treated with dihydralazine. Eighty-one percent of the patients treated with dihydralazine developed a serious ventricular arrhythmia, compared with 17% of those treated with labetalol. Individuals treated with labetalol experienced a significant decrease in average heart rate, but individuals treated with dihydralazine experienced a significant increase.

Health aspects, Complications and side effects, Drug therapy, Hydralazine, Ventricular tachycardia, Labetalol

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