Introduction
Our bodies contain a wide variety of proteins, each capable of carrying out a number of crucial functions. For instance, proteins are the building blocks of our bones, neurological system, and organ tissues. They also direct how our bodies process food and medicines. Genes are made up of DNA that, when appropriately interpreted by proteins, can provide detailed instructions for the body's proper function. The genome is thought to include roughly 22,000 genes. Each gene is inherited or passed down from generation to generation as a single unit at a specific position on one of our 23 chromosomes. Each gene has two copies since we have two copies of each chromosome. Our parents each give us one copy, and we then give one of our two copies to each of our offspring.
What Are Hereditary Diseases?
At all stages of development, hereditary diseases play a significant role in morbidity and mortality. Nearly 10% of people experience a significant hereditary disease at some point. As a result, these disorders significantly impact both the public health and the healthcare system. A significant contributor to reproductive failure, particularly in fetal loss during the first trimester, is cytogenetic abnormalities in the fetus. Significantly more severe developmental malformations, such as neural tube defects, occur in spontaneously aborted pregnancies and stillborn babies than in term live births.
Hereditary diseases are caused by changes in a person's genetic material (DNA), passed down through the generations. A hereditary condition is frequently called one that "runs in the family." It is given to a child by one or both parents, who may then pass it on to their offspring. "Hereditary" and "genetic" may be used interchangeably when referring to inherited disorders because genetic alterations cause hereditary diseases. A genetic condition, however, is also caused by a gene mutation and may or may not run in the family. These mutations might happen at random or as a result of the environment. They are passed on to a person's offspring in the same way that a hereditary disease does.
Each hereditary condition has its genetic makeup. In certain instances, one genetic condition is caused by all the errors in a given gene. In other instances, distinct health or developmental issues or even distinct genetic illnesses can result from various alterations within the same gene. Sometimes the same genetic condition might result from alterations in numerous related genes.
What Is the Mechanism Behind Hereditary Diseases?
Usually, genetic abnormalities are inherited (transmitted) in one of two ways: dominantly or recessively. On our 22 numbered chromosomes, every gene is duplicated twice in each of us. Additionally, males have one copy of each gene on the X chromosome and one copy of each gene on the Y chromosome, but females have two copies of every gene on the X chromosome.
The disease can still manifest when only one of two genes in a dominant condition contains abnormal DNA. Accordingly, there is a 50/50 probability that each child will inherit the DNA alteration from a parent who has it. When a condition is recessive, both gene copies must include mutations for the condition to manifest. For a child to be impacted, both parents must have at least one copy of the particular gene mutation.
In other populations, recessive gene alterations might be more prevalent. For instance, those with West African heritage are more likely to have sickle cell disease, and people with North European ancestry are more likely to have cystic fibrosis.
What Are the Most Common Hereditary Diseases?
-
Sickle cell disease.
-
Cystic fibrosis.
-
Tay Sachs.
-
Huntington's disease.
-
Muscular dystrophy.
-
Marfan syndrome.
-
Neurofibromatosis type 1.
-
Congenital deafness.
-
Cystic fibrosis.
-
Beta-thalassemia.
-
Certain cancers, such as skin cancer, breast cancer, prostate cancer, and lung cancer.
-
Cardiomyopathies.
-
Arthritis.
-
Inherited arrhythmia syndromes.
-
Neuromuscular disorders.
-
Familial hypercholesterolemia.
Can Hereditary Diseases Be Prevented?
Hereditary diseases cannot be cured; they can only be prevented. The hereditary condition is one of many factors that contribute to infant mortality. Genetic diseases account for 20% of infant mortality in wealthy nations.
Therefore, it's essential to understand genes since it has the potential for the newborn to develop a severe genetic condition. The greatest way to ensure that the child will be healthy is to get screened before marriage and, if possible, before conception.
-
Screening Before Conception:
The carriers are typically healthy individuals, but there is a substantial probability of producing an afflicted kid if both parents carry the same gene mutation. The Carrier Genetic Test (CGT), created by IGENOMIX, is a genetic test that can assist in determining whether the parents are carriers of a genetic condition. Both couples must be subjected to the exam. When both couples are discovered to be carriers of the same recessive gene, they can learn more about preimplantation genetic diagnosis (PGD) from their specialist to produce a healthy child.
Carriers can be found using fundamental blood testing, enabling couples to be identified and warned of their risk before conception.
-
First-Trimester Screening:
The first-trimester screening is a routine procedure that is carried out between 10 and 13 weeks and six days of gestation and combines blood screening with an ultrasound evaluation of the nuchal translucency. Benefits of first-trimester screening include how to proceed with other pregnancy care, such as pursuing additional diagnostic testing, genetic counseling, consulting with a maternal-fetal medicine specialist, or, if desired, terminating the pregnancy.
-
Quad Screen:
The initial serum screening test, known as the quadruple marker screen, sometimes the quad screen, is carried out between 15 and 22 weeks of gestation. It involves measuring the levels of several proteins secreted by the pregnancy in the serum, including hCG, alpha-fetoprotein (AFP), inhibin A, and unconjugated estriol. The quad screen can detect open neural tube anomalies in addition to aneuploidy.
-
Other Screening Modalities:
Some of the other screening methods were integrated, stepwise sequential, and dependent screening. In integrated screening, a first-trimester test is conducted, the results of which are not given to the patient or healthcare practitioner, and then a quad screen is conducted. The patient is then given a thorough risk assessment of her aneuploidy risk in the second trimester by combining these values into a single risk estimate.
-
Prenatal Diagnosis Methods:
Prenatal diagnosis methods are getting more accessible; for instance, chorionic villus sampling (CVS) can now diagnose about nine weeks into a pregnancy, allowing for early termination if desired. Methods for utilizing gene mapping for prenatal diagnosis are also better.
What Are the Recent Advances in the Prevention of Hereditary Diseases?
Cell-Free DNA: Cell-free DNA, also known as noninvasive prenatal screening, became available in 2011. Using this relatively new technique, cell-free DNA fragments from the pregnancy are recovered from a sample of the mother's serum. This DNA is released from apoptotic trophoblasts and is mainly of placental origin. Although fetal fraction rises with gestational age, it is consistently higher than 10% as early as ten weeks. With a detection rate of 99%, this screening test has the greatest trisomy 21 detection rate of any trisomy 21 screening test currently available. However, it is advised that women with a high pre-test risk of aneuploidy use cell-free DNA for aneuploidy screening. Maternal age greater than 35 years at delivery, ultrasonographic findings indicating increased aneuploidy risk, a prior pregnancy affected by a trisomy, parental balanced Robertsonian translocation increasing the risk of trisomy 13 or 21, and high-risk first- or second-trimester aneuploidy screening results are all indications to perform a cell-free DNA prenatal screening. Identifying fetal sex and fetal Rh status in pregnancies at risk of Rh isoimmunization with great accuracy and precision are two additional advantages of cell-free DNA.
Conclusion
Genes are a source of structural and metabolic variations that account for overt disease and predisposition to the disease under specific environmental conditions. Genetic testing has promise because it can identify gene mutations, or changes in the genetic makeup, which may lead to disease. Early disease identification can help you get a head start on necessary lifestyle adjustments or get the proper medical advice for prevention or treatment sooner. Genetic tests are available for most of the more than 50 distinct hereditary cancer syndromes. It's critical to comprehend the advantages, hazards, and restrictions of testing and the family's medical history.
