What environmental factors may increase the incidence of chromosomal aberrations?

What increases the risk of chromosomal abnormalities?

The risk of chromosomal abnormality increases with maternal age. The chance of having a child affected by Down syndrome increases from about 1 in 1,250 for a woman who conceives at age 25, to about 1 in 100 for a woman who conceives at age 40.

Can environmental factors cause chromosomal abnormalities?

In the human population, it has been estimated that close to 70% of congenital defects are of uncertain or unknown cause; approximately 20% may be due to genetic factors such as mutations and chromosomal abnormalities, and 10% can be attributed to teratogenic environmental factors such as chemicals, therapeutic drugs, …

What is the most common cause of chromosomal abnormalities?

A chromosomal abnormality occurs when a child inherits too many or two few chromosomes. The most common cause of chromosomal abnormalities is the age of the mother. As the mother ages, the ovum is more likely to suffer abnormalities due to longer term exposure to environmental factors.

Why do chromosomal abnormalities occur?

Some chromosomal conditions are caused by changes in the number of chromosomes. These changes are not inherited, but occur as random events during the formation of reproductive cells (eggs and sperm). An error in cell division called nondisjunction results in reproductive cells with an abnormal number of chromosomes.

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Why advanced maternal age has increased likelihood of having a child with chromosomal abnormalities?

Fetal chromosomal abnormalities may be caused by a nondisjunction phenomenon that occurs in the period of meiosis during maternal oogenesis, which has been reported to have a direct association with maternal age. Therefore, pregnancy in advanced age is a critical risk factor for fetal chromosomal abnormalities [24].

What environmental factors may cause malformations in the developing embryo?

An environmental cause can include drugs, alcohol, or a disease the mother has that can increase the chance for the baby to be born with a birth defect. An agent that can cause a birth defect is known as a teratogen. Multifactorial birth defects are caused by a combination of genes and environmental exposures.

What are environmental factors?

Environmental factors include temperature, food, pollutants, population density, sound, light, and parasites. The diversity of environmental stresses that have been shown to cause an increase in asymmetry is probably not exclusive; many other kinds of stress might provide similar effects.

What are four environmental hazards that can affect a fetus?

These chemicals include commonly known hazards such as lead, mercury, and environmental tobacco smoke, as well as some pesticides, solvents, products containing chlorine, and other chemicals referred to as “persistent organic pollutants.” The fetus is particularly vulnerable to environmental chemicals that can disrupt …

What are chromosomal aberrations?

Chromosomal aberrations are changes in chromosome structure or number. Most chromosomal aberrations are known as aneuploidies, or different numbers of chromosomes other than pairs. A trisomy is an aneuploidy with one extra chromosome, for a total of 3, and a monosomy has one fewer chromosome, for a total of 1.

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What causes the most common chromosomal abnormality called trisomy 21?

Abstract. Trisomy 21 (Down syndrome) is the most common autosomal trisomy in newborns, and is strongly associated with increasing maternal age. Trisomy 21 results most commonly from maternal meiotic nondisjunction. Unbalanced translocation accounts for up to 4% of cases.