November 22, 2023

Lily Sharkey

11th Grade

Dominican Academy

Every person has more than 20,000 genes that code for their very existence. Genes are made up of deoxyribonucleic acid (DNA) wound up into tight structures called chromosomes. All chromosomes are found in the nucleus, the core structure of each cell. Every person has two replicas of each gene, one inherited from each parent. A mutation, which is a variant or alteration in the DNA, can drastically change what the DNA codes for. The variant can be benign, meaning they don’t pose a serious threat to one’s health, or pathogenic, which causes genetic and health issues. 

Genetic disorders are just that— diseases caused by a pathogenic variation in a gene. Some genetic disorders are inherited at birth, while others develop later in life. A person can even be a carrier for a disease, meaning they’ve inherited the mutation from their parents, but don’t exhibit symptoms. Genetic disorders can be chromosomal, multifactorial, or monogenic. Chromosomal genetic disorders are caused by a mutation on the chromosome, such as missing or duplicated chromosomal material. Multifactorial genetic disorders are caused by a mix of genetic and environmental factors, such as chemical/radiation exposure, diet, smoking, or UV exposure; scientists still don’t fully understand how these exposures lead to DNA mutations. Monogenic genetic diseases are caused by one gene mutation.

Although many genetic disorders are yet to have a cure, certain treatments do exist to improve a patient’s quality of life. Some of these treatments include medication to minimize symptoms, chemotherapy to control atypical cell growth, blood transfusion to regenerate normal levels of blood cells, surgery to repair complications, and organ transplant. Of course, appropriate treatment depends on the individual’s genetic disorder, symptoms, and complications, and there is seldom a uniform treatment that can be applied to all patients. There is little that can be done to prevent a genetic disorder, as the causes are found in the fundamental genome of a person. 

Duchenne Muscular Dystrophy (DMD) is an example of an X-linked recessive genetic disorder that causes muscle weakness and degeneration. DMD predominantly manifests in individuals with XY chromosomes (those assigned male at birth). Duchenne Muscular Dystrophy is caused by the DMD gene, the second-largest human gene that encodes dystrophin. This muscle protein allows muscles to recover from physical strains resulting from typical movement. Patients with DMD create little to no dystrophin, meaning that their cells weaken and eventually die. DMD often affects the lower limbs, but it can also manifest in the muscles of internal organs like the diaphragm, making breathing difficult. Other symptoms include pseudohypertrophy, the “false enlargement” of muscles (such as calf muscles) due to a buildup of fat and connective tissue that replaces muscle cells that have died, and cardiomyopathy, progressive heart enlargement. Due to these cardiovascular and respiratory complications, the life expectancy of those with DMD is from their mid-to-late 20s.

DMD is X-linked, meaning it is connected to the X chromosome. Because DMD is recessive, a person needs two copies of the gene mutation to express the disease. However, because males only have one X chromosome, they only need one copy of the mutated gene; this is why DMD primarily presents itself in males. Females with XX chromosomes may be carriers for the gene, but will most likely only inherit one affected gene. Thus, they are still able to create enough dystrophin and not be impacted. XY children of carrier mothers have a 50% chance of inheriting the mutated gene; they do not receive the gene from a carrier father, as children receive their X chromosome from their mother. However, DMD can be caused by a new mutation in the mother’s ova (egg cells) because the large size of the DMD gene makes it vulnerable to mutations.

In summary, genetic disorders are mutations in one’s DNA or chromosomes. Although there is often no way to prevent genetic diseases, it is possible to undergo screenings and counseling to determine the probability of a child having a genetic disease. If the genetic disease is identified early on, then the child can begin treatments to manage symptoms and prevent complications. With further scientific exploration, it is hopeful that more genetic disorders will have treatments in the future as Duchenne Muscular Dystrophy does.