Once you have a basic understanding of what a typical cell includes (23 pairs of chromosomes), it is easier to understand how chromosomal abnormalities occur. A chromosomal abnormality occurs when a gamete does not have a normal set of 23 chromosomes. Down Syndrome is the most common chromosomal abnormality. It occurs when an extra chromosome causes mild to severe cognitive and physical delays. Advanced maternal age appears to have an impact on the likelihood of a woman giving birth to a child with Down Syndrome. If a mother is age 20, this syndrome occurs in 1 in 1,900 births. If a mother is 35, it occurs in 1 out of 300 births. If a mother is age 45, it occurs in 1 out of 30 births (National Institute of Health, 2018). Down Syndrome is interesting when considering the nature vs. nurture debate. Although the condition cannot be reversed, early intervention can lead to much more positive outcomes. Children with Down Syndrome can grow up to be adults who live independent, healthy, productive lives.

Some other common chromosomal conditions that may be encountered when working with young children:

Klinefelter Syndrome occurs when an extra X chromosome causes physical abnormalities. It occurs in one out of six hundred male births. Hormone therapy can be effective.

Fragile X Syndrome is an abnormality in the X chromosome that can cause cognitive delays, learning disabilities and a short attention span. It is more common in males than females.

Turner Syndrome, which occurs in one out of two thousand five hundred live births, develops when a female is missing an X chromosome. It causes cognitive delays and sexual underdevelopment. Hormone therapy in childhood and puberty can be beneficial.

XYY Syndrome occurs when an extra Y chromosome is present. It can cause above average height (Santrock, 2013).

Gene-Linked Abnormalities

Gene-linked abnormalities can be caused by harmful genes. Here are some examples of gene-linked abnormalities:

Phenylketonuria, or PKU occurs when an individual cannot properly metabolize an amino acid; a special diet can result in average intelligence and a normal life span. If left untreated, it causes mental retardation. This is an excellent example of how nurture (the environment) can positively impact nature (the results of genetic inheritance). If this condition is treated, a child goes on to live a perfectly normal, healthy life.

Sickle-cell anemia occurs mainly in the African American population. It is caused by a recessive gene. It is a blood disorder that limits the body’s oxygen supply. It can cause heart and kidney failure, as well as joint swelling. There is no cure for sickle cell anemia.

Prenatal Testing for Genetic Abnormalities

There are several tests that can be performed prenatally to give women information about how the fetus is developing. An ultrasound is the most common prenatal test. High frequency sound waves are directed into the pregnant woman’s abdomen. The echo from the sounds creates a picture. Ultrasounds can detect many abnormalities in the fetus, including microencephaly, a condition caused by an abnormally small brain. Ultrasounds can also determine the number of fetuses and give clues to the baby’s sex. The ultrasound procedure is non-invasive, meaning it is done outside the body. There is no risk to the mother or the fetus when this test is administered (Berk, 2017).

Between the 10th and 12th weeks of pregnancy, chorionic villi sampling may be performed. In this procedure, a sample of the placenta is taken to test for chromosomal or genetic abnormalities. There is a small risk of limb deformity, and this test can cause false positives if a woman does not know the exact date of conception.

Amniocentesis is another test that is administered to many women during pregnancy. During an amniocentesis, a sample of amniotic fluid is taken to test for chromosomal and metabolic disorders. This is an invasive procedure because the medical professional is going into the amniotic sac to take a sample of fluid. Amniocentesis provides a small risk of miscarriage but provides a great deal of accurate information regarding chromosomal and genetic conditions (Berk, 2017; Santrock, 2013).

Maternal blood screening (sometimes called the AFP test) identifies pregnancies that have an elevated risk for birth defects such as spina bifida. Triple screen measures three substances in the mother’s blood. It is noninvasive because the doctor is not going into the amniotic sac. After an abnormal triple screen, the next step is usually an ultrasound. If an ultrasound does not explain the abnormal triple screen, amniocentesis is typically used.

All these prenatal tests give women important information about their developing fetus (Berk, 2017).

Other Concerns

For some women, conceiving a child can be extremely difficult. Infertility is an inability to conceive after 12 months of regular intercourse (Santrock, 2013). As women have chosen to have children later in life, the rates of infertility have risen, due in some part to advanced maternal age. There are several strategies to deal with infertility: in vitro fertilization (IVF), gamete intrafallopian transfer (GITF) and zygote intrafallopian transfer (ZIFT). IVF has a 31% success rate. GITF has a 24.5% success rate and ZIFT has a 29.2% success rate (Zarinara, 2021). People who continue to struggle with infertility often consider adoption.