- Family history of a genetic disorder
- Prior child with a genetic disorder
- One parent has a chromosomal abnormality
- Advanced maternal age (35 or older)
- Advanced paternal age (40 or older)
- Multiple miscarriages or prior stillbirth
It is important to know that some birth defects, developmental delays, and/or illnesses can be caused by prenatal exposure to drugs, alcohol, or other environmental factors.
There are several types of disorders that can be seen during pregnancy:
Single gene disorders occur when a change in one gene causes a disease. Examples include cystic fibrosis, sickle cell anemia, Tay-Sachs disease, hemophilia, and Marfan syndrome.
Chromosomal abnormalities occur where there are missing or extra chromosomes, or pieces of chromosomes. Down syndrome, the most common chromosomal abnormality, is caused by an extra chromosome number 21. Chromosome abnormalities can be inherited from a parent or they can happen by chance.
Multifactorial or complex disorders are caused by a combination of genetic predispositions and environmental factors, which makes it harder to predict who may be at risk. Examples include heart defects, cleft lip or cleft palate, and spina bifida.
Teratogenic disorders occur when the baby is exposed to substances during pregnancy that cause abnormalities, otherwise known as “teratogens.” Babies are very sensitive in the first trimester, when all of the organs are developing. Teratogens include alcohol, drugs, lead, high levels of radiation exposure, and certain medications, infections and toxic substances.
A genetic disease is any disease caused by an abnormality in the genetic makeup of an individual. The genetic abnormality can range from minuscule to major — from a discrete mutation in a single base in the DNA of a single gene to a gross chromosomal abnormality involving the addition or subtraction of an entire chromosome or set of chromosomes. Some people inherit genetic disorders from the parents, while acquired changes or mutations in a preexisting gene or group of genes cause other genetic diseases. Genetic mutations can occur either randomly or due to some environmental exposure.
Typically, the nucleus of an individual cell contains 23 pairs of chromosomes, but Down syndrome occurs when the 21st chromosome is copied an extra time in all or some cells. Nurse practitioners and physicians commonly perform detailed prenatal screening tests, like blood tests, that detect quantities of chromosomal material and other substances in a mother’s blood. This type of testing can determine, with high accuracy, whether or not a child will be born with Down syndrome. When a person is diagnosed with Down syndrome, they are likely to exhibit varying levels of mild to severe cognitive delays. Other markers of Down syndrome include a higher disposition for congenital heart defects, low muscle tone, smaller physical stature, and an upward slant to the eyes. According to the Centers for Disease Control and Prevention (CDC), approximately one in every 700 babies born in the US will have Down syndrome. Also, the older a mother is at the time of birth, the more likely the child is to have Down syndrome. 
Thalassemia is a family of hereditary genetic conditions that limits the amount of hemoglobin an individual can naturally produce. This condition inhibits oxygen flow throughout the body. There is a 25 percent chance that children who inherit the Thalassemia gene from both parents will be born with Thalassemia. People who are especially likely to be carriers of the faulty gene that is responsible for Thalassemia include those of Southeast Asian, Indian, Chinese, Middle Eastern, Mediterranean, and Northern African descent. With any form of Thalassemia usually comes severe anemia, which may require specialized care such as regular blood transfusions and chelation therapy.
Cystic Fibrosis is a chronic, genetic condition that causes patients to produce thick and sticky mucus, inhibiting their respiratory, digestive, and reproductive systems. Like Thalassemia, the disease is commonly inherited at a 25 percent rate when both parents have the Cystic Fibrosis gene. In the United States, there are close to 30,000 people living with Cystic Fibrosis, and they frequently develop greater health problems. For instance, 95 percent of male Cystic Fibrosis patients are sterile, and the median age of survival for all patients is 33.4 years. Educated nurse practitioners can extend the typical patient’s survival time by offering effective care strategies that feature physical therapy, as well as dietary and medical supplementation.
The genetic condition known as Tay-Sachs is carried by about one in every 27 Jewish people, and by approximately one of every 250 members of the general population. The condition is caused by a chromosomal defect similar to that of Down syndrome. Unlike Down syndrome, however, Tay-Sachs results from a defect found in chromosome #15, and the disorder is irreversibly fatal when found in children. Tay-Sachs disease gradually destroys the nervous system, frequently resulting in death by age five. Adults can also be diagnosed with Late-Onset Tay-Sachs disease, which causes a manageable level of diminished cognitive ability. While detecting Tay-Sachs can be accomplished by using enzyme assay methods or DNA studies, an option does exist to prevent the risk entirely. Assisted reproductive therapy techniques can be conducted that test in-vitro embryos for Tay-Sachs before implanting them into the mother. This can allow only healthy embryos to be selected.
Sickle Cell Disease is a lifelong genetic condition that may be inherited when the Sickle Cell trait is passed down by both parents to their children. The trait is more commonly inherited by people with a sub-Saharan, Indian, or Mediterranean heritage. Sickle Cell Disease causes red blood cells to change from their usual donut shape to a sickle shape. This causes the cells to clump together and become caught in blood vessels, triggering severe pain and serious complications such as infections, organ damage, and acute respiratory syndrome. According to the CDC, Sickle Cell Disease affects approximately 100,000 Americans. Additionally, one in every 365 African-American babies is born with Sickle Cell Disease. In contrast, one in every 16,300 Hispanic-American babies is diagnosed with the disease. Modern advancements in medicine have limited the mortality rate of Sickle Cell Disease by providing a greater variety of vaccines and treatment options.
Giving birth to a child with a genetic condition can be concerning for parents, but effective ongoing care from trained nursing professionals can significantly ease the impact. Through a Doctor of Science in Nursing program, nurse practitioners can expand their knowledge and practical ability to confront and mitigate these disorders. By adding new expertise in the leading-edge detection, prevention, and treatment of genetic disorders, advanced-degreed nurses can play a key role in helping parents, children, adult sufferers, and society at large.
At birth, while individually rare, collectively genetic disorders are relatively common, with a combined prevalence of around 1-2% in the UK. Some 4,000 inherited diseases are known to be associated with mutations in single genes, with recognisable patterns of inheritance. These are classified according to the chromosome on which they are found: autosomal, X-linked or Y-linked and are covered in more detail in the following section: Basic genomic concepts.
Single gene mutations are not all congenital (present in the phenotype at birth). Subsets of common disease that develop later in life can be prevalent in several members of the same family and the disease shows a recognisable Mendelian inheritance pattern associated with a single gene. This suggests the existence of a single mutation that confers a high risk of disease developing in that family. Single gene subsets of common disease typically account for a maximum of ~5% of the total burden of disease. An example is familial hypercholesterolemia, a dominantly inherited condition characterised by a build-up of cholesterol and a high risk of premature cardiovascular disease. Another example is inheriting a mutated BRCA1/BRCA2 gene and the subsequent increased risk of developing breast cancer.
Susceptibility to common diseases that typically occur in middle and later life can also be associated with genetics other than with a single mutation. Certain genetic variants may increase the risk but do not absolutely predict occurrence, such as coronary heart disease (e.g. VAMP8 variant), diabetes (e.g. PCSK9 variant) and cancer (e.g. rs4143094 variant for bowel cancer). Cancer results from genetic alterations, occurring when DNA instructions are damaged so that the cell escapes normal regulation when replicating. Most genetic alterations that lead to cancerous behaviour arise in the individual and do not affect the germline (the genomic material that is heritable).
This is a rapidly expanding field, with the understanding that both the environment and individual lifestyle can directly interact with the genome to influence epigenetic change. This, therefore, has significant implications for public health’s role in disease prevention and clinical implications. Identification of epigenetic changes could provide an indication of an increased risk of disease in later life if they result from potentially harmful exposures in populations. Epigenetic changes could also be potentially modifiable through lifestyle and diet changes.
There are however challenges in the study of and application of epigenetics, both with adapting technology to epidemiology studies to identify mechanisms associated with exposure and disease and recognising that epigenetic changes associated with environmental exposures or disease outcomes have typically been small in magnitude.
The discipline of public health genetics is centred on the involvement of genes as determinants of health and their interactions with other genetic, environmental or social factors. As mentioned above, the majority of diseases are multifactorial and involve genetics and the environment. If an interaction with the environment is required for disease to develop, this provides an important opportunity to modify the risk of disease by altering the environment. An understanding of the genetic characteristics of disease may also help to understand the relative effectiveness of different pharmaceutical treatments in different people, a field termed pharmacogenetics. Another example of the role of genes in health is gene therapy. This is the use of viruses and plasmids (DNA naturally existing in bacteria distinct from chromosomal DNA) to insert genetic material in cells of people with a disease such as cystic fibrosis. The purpose is to compensate for abnormal genes or to make a beneficial protein.