Sickle cell anemia is an inherited disease that causes abnormal red blood cells. It is a lifelong disease. Sickle cell trait is not the same as sickle cell disease. If your child has sickle cell trait, it means that he or she has one abnormal gene that causes sickle cell disease. For someone to have sickle cell disease, the person needs 2 abnormal sickle cell genes. About 2.5 million Americans have sickle cell trait.
Having sickle cell trait does not cause symptoms or other problems that occur with sickle cell disease. Normal hemoglobin is called hemoglobin A, but people with sickle cell disease have only hemoglobin S, which turns normal, round red blood cells into abnormally curved (sickle) shapes.
Normally, a person inherits two genes (one from each parent) that produce beta-globin, a protein needed to produce normal hemoglobin (hemoglobin A). A person with sickle cell trait inherits one normal beta-globin gene (hemoglobin A) and one defective gene (hemoglobin S).
Sickle-cell anaemia is particularly common among people whose ancestors come from sub-Saharan Africa, India, Saudi Arabia and Mediterranean countries. Migration raised the frequency of the gene in the American continent. In some areas of sub-Saharan Africa, up to 2% of all children are born with the condition. In broad terms, the prevalence of the sickle-cell trait (healthy carriers who have inherited the mutant gene from only one parent) ranges between 10% and 40% across equatorial Africa and decreases to between 1% and 2% on the north African coast and <1% in South Africa. This distribution reflects the fact that sickle-cell trait confers a survival advantage against malaria and that selection pressure due to malaria has resulted in high frequencies of the mutant gene especially in areas of high malarial transmission.
One of every 600 black people in the United States has sickle cell anemia. In addition, sickle cell–hemoglobin C disease and sickle cell–ß-thalassemia, which are other common genotypes of sickle cell disease, together are as common as sickle cell anemia. Sickle hemoglobin (hemoglobin S, 2 ß2S) accounts for over half the hemoglobin in patients with these disorders. Eight percent of black Americans are heterozygous carriers of the sickle cell trait; about 40 percent of their hemoglobin is hemoglobin S. They do not have anemia and need neither treatment nor occupational restrictions. About 5 percent have hematuria at some time and most cannot concentrate their urine, but these are clinically unimportant abnormalities.
Because sickle cell anemia is inherited, it can be prevented if couples who both carry the sickle cell trait gene do not have children. When both parents are carriers, each child has a 25% risk of having sickle cell anemia and a 50% risk of being a carrier.Screening programs are available to identify sickle trait carriers. If you are thinking about having a child and have sickle cell anemia or are a carrier, it is a good idea to seek genetic counseling.
Although pregnancy does not increase the rates of asymptomatic bacteriuria, it does increase the risk that it will progress to a full-blown infection. About 2% to 11% of pregnant women have asymptomatic bacteriuria and, of those, 13% to 27% will develop a kidney infection late in their term. (Frequent urination, a common symptom of UTI, during early pregnancy is most likely due to pressure on the bladder.)
Although all pregnant women should be tested for UTIs, those at particularly high risk are those with the following conditions or situations:
*Diabetes.
*Sickle cell trait.
*Members of low-income groups.
*Women who have had many children.
*A history of childhood UTIs.
*Women who have undergone a cesarean section with catheterization of the bladder.
*Women who have received epidural anesthesia.
African-American women with the sickle cell trait are less likely to delivery prematurely and more likely to have multiple births than their counterparts without the sickle cell trait, according to a report in the medical journal Obstetrics & Gynecology.
Women of African-American descent should therefor be offered special screening for blood disorders during pregnancy because "there are clear implications for genetic counseling and screening for urinary tract infections" if the sickle cell trait is detected, Dr. Allison S. Bryant told Reuters Health.
Because of the increased risk of multiple births, she added, physicians should know if a woman is a sickle cell carrier, because early detection of multiple pregnancies is important to ensure good outcomes.
Bryant, from the University of California, San Francisco, and colleagues conducted a study with more than 5,000 African-American women who delivered between 1976 and 2001. Of this group, 6.5 percent carried the sickle cell trait.
Compared with the women without the sickle cell trait, women with the trait were 85 percent less likely to deliver before 32 weeks and 94 percent more likely to be carrying more than one fetus. These relationships were still seen after the effects of assisted reproductive technologies and other influential factors were considered, the report indicates.
The risk of preterm delivery was even lower among women carrying more than one fetus.
There have been other reports of an association between the sickle cell trait and more pregnancies and more live births, Bryant noted.
The sickle cell trait is known to provide a survival advantage in areas were malaria is common, such as Africa. This is because malarial parasite, transmitted to humans by the bite of an infected mosquito, attacks red blood cells, which are less likely to be infected when they have a sickle shape.
Some authors have attributed the features of these pregnancies to the genetic selection of the sickle cell trait -- even in areas where malaria is not a threat. The findings of the current study "may fit into this framework," the researcher concluded.
An another study is to assess the pregnancy outcome among women with sickle cell trait [SCT], and to compare it with a control group of women with normal hemoglobin.The incidence of abortion and neonatal death in previous pregnancies was significantly increased among SCT women. So, pregnant women with SCT need special care and attention during pregnancy, labor, puerperium and surgery. They should be identified early to prevent complications such as anemia, infection and fetal wastage.
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