Search

Displaying 1 - 6 of 6 items.

Androgen Insensitivity Syndrome

Androgen Insensitivity Syndrome (AIS) is a human disorder in which an individual's genetic sex (genotype) differs from that individual's observable secondary sex characteristics (phenotypes). A fetus with AIS is genetically male with a 46,XY genotype. The term 46,XY refers to the chromosomes found in most cells of the fetus. Most cells have a total of 46 autosomes, or non-sex chromosomes, and a pair sex chromosomes, XX for genetic females, or XY for genetic males.

Format: Articles

Subject: Disorders

Anencephaly

Anencephaly is an open neural tube defect, meaning that part of the neural tube does not properly close or that it has reopened during early embryogenesis. An embryo with anencephaly develops without the top of the skull, but retains a partial skull, including the face. Anencephaly is one of the most common birth defects of the neural tube, occurring at a rate of approximately one in one thousand human pregnancies. The condition can be caused by environmental exposure to chemicals, dietary deficiencies, or genetic mutations.

Format: Articles

Subject: Disorders, Reproduction

Agent Orange as a Cause of Spina Bifida

Spina bifida is a birth defect that affects the spines of developing fetuses and infants, and research in the 20th century indicated that chemicals in the herbicide Agent Orange likely lead to the birth defect. People with spina bifida can have nerve damage, paralysis, and mental disabilities. During the Vietnam War in the 1960s, the US military employed Agent Orange and other herbicides to destroy enemy crops and forest cover until 1970.

Format: Articles

Subject: Disorders

Agent Orange Birth Defects

Sprayed extensively by the US military in Vietnam, Agent Orange contained a dioxin contaminant later found to be toxic to humans. Despite reports by Vietnamese citizens and Vietnam War veterans of increased rates of stillbirths and birth defects in their children, studies in the 1980s showed conflicting evidence for an association between the two. In 1996, the US National Academy of Sciences reported that there was evidence that suggested dioxin and Agent Orange exposure caused spina bifida, a birth defect in which the spinal cord develops improperly.

Format: Articles

Subject: Disorders

Methylmercury and Human Embryonic Development

Methylmercury (MeHg) is an organic form of mercury that can damage the developing brains of human fetuses. Women who consume methylmercury during pregnancy can bear children who have neurological issues because methylmercury has toxic effects on the nervous system during embryonic development. During the third week of gestation, the human nervous system begins to form in the embryo. During this gestational period, the embryo's nervous system is particularly susceptible to the influence of neurotoxins like methylmercury that can result in abnormalities.

Format: Articles

Subject: Reproduction, Disorders

Transposition of the Great Arteries (TGA)

Transposition of the great arteries or TGA is a potentially fatal congenital heart malformation where the pulmonary artery and the aorta are switched. The switch means that the aorta, which normally carries oxygenated blood, carries deoxygenated blood. There are two types of the malformation, d-TGA where no oxygen reaches the body and l-TGA where some oxygenated blood circulates. In the US, the Centers for Disease Control estimate that about 1,901 infants are born each year with TGA, or about one for every 2,000 births.

Format: Articles

Subject: Disorders