Experts say the most common genetic disorders result from DNA mutations in genes inherited from our parents. They classify these issues as chromosomal, complex (a.k.a. multifactorial), and single-gene (a.k.a. monogenic). 

Chromosomal disorders target the structures that hold genes within each cell. Some prime examples are Down syndrome, autism spectrum disorder, and Klinefelter syndrome, in which assigned males at birth have an extra X chromosome. 

Complex/multifactorial genetic disorders are a byproduct of gene mutations from environmental factors such as chemical exposure, as well as the use of substances like tobacco and alcohol. Arthritis, late-onset Alzheimer’s disease, diabetes, and migraines fall under this category. 

As the name suggests, monogenic disorders result from a mutation in one gene. Some examples are sickle cell disease, cystic fibrosis, congenital deafness, and muscular dystrophy.

However, there are much more special cases, like Marfan syndrome. On the surface, it looks like a person with a lanky frame and a narrow facial structure. However, it is a result of a severe, incurable chronic disorder. 

Marfan syndrome affects the body’s connective tissues, causing the people stricken with it to have unusually long limbs. While it may seem harmless, this condition may cause life-threatening issues like aortic aneurysms because it also affects the heart and blood vessels. 

Doctors usually prescribe blood pressure medications to patients with Marfan syndrome to alleviate the pressure on the aorta. In some cases, people with this condition must undergo preventive surgery.

If you’ve seen a person with cat-like eyes or pupils shaped like keyholes, they are likely suffering from coloboma. This hereditary disease may affect one or both eyes and cause various symptoms, from light sensitivity to complete vision loss. 

Coloboma can develop in various parts of the eye, from the iris to the lens, the retina, and the optic nerve. According to the American Academy of Ophthalmology, the disease can begin as early as infancy and requires immediate evaluation. 

However, like Marfan syndrome, coloboma has no cure. Ophthalmologists usually require their patients to wear colored contact lenses to make their irises appear rounder. They may also prescribe low-vision devices, like side shields for eyeglasses, to control light reflection.

Heterochromia is an eye-related disorder that could draw more amazement than concern. People stricken with this condition have different-colored irises, with the left eye being blue and the right eye being green. There is also central heterochromia, where the eye has a distinct inner ring of a different color from the outer iris. 

For the most part, heterochromia has no other symptoms apart from differing iris colors. However, it could also be a byproduct of other conditions, such as Horner syndrome (eyelid drooping caused by disrupted nerve fibers connecting the brain to the eye) and Hirschsprung’s disease (caused by improperly developed intestinal nerve cells). 

But because of its pleasantly peculiar nature, heterochromia is usually deemed “incredibly beautiful,” especially since many A-list celebrities share this condition. Some of the famous names with different-colored eyes include Mila Kunis, Kiefer Sutherland, Kate Bosworth, and Christopher Walken, to name a few.

You were likely amazed and freaked out at the same time when someone showed you how their thumb bends a full 90 degrees backward. Joint hypermobility syndrome, a.k.a double-jointedness, isn’t an unusual genetic condition. Still, there is more to it than meets the eye. 

The National Library of Medicine noted that joint hypermobility syndrome could be a precursor to more serious conditions like Ehlers-Danlos syndrome. Like Marfan syndrome, it affects the body’s connective tissues and, in worst cases, ruptures blood vessels. 

For the most part, double-jointed people do not experience any outright symptoms from their condition. However, pain and stiffness in the joints and muscles and constant dislocations may occur in more severe cases.

These days, it isn’t uncommon to see people with patches on their skin that are a different color. This condition is called vitiligo, an auto-immune disorder where the body’s immune cells attack the melanocytes, the cells responsible for making skin pigment. 

According to the National Institute of Arthritis and Musculoskeletal Skin Diseases, vitiligo may develop at any age. However, the discolored skin patches may begin to appear before the age of 20. In some cases, it starts to manifest in early childhood. People with other autoimmune diseases like psoriasis and rheumatoid arthritis are also at risk of developing this condition. 

Experts would usually disregard treatment options for vitiligo since it causes no further harm. However, since people with this condition are more prone to developing self-esteem issues, light therapy, depigmentation therapy, and surgery are potential solutions.

Similar to vitiligo, Albinism is a rare genetic disorder that affects skin pigment and causes discoloration. However, in this case, people suffer from a lack of melanin, a chemical responsible for producing hair, eye, and skin color. 

According to published research, albinism occurs in one in every 3,000 people worldwide and affects all races and ethnic groups. Besides the overly pale skin, people with this condition suffer from vision problems, sensitivity to light, and rapid eye movement. 

Albinism has no cure and increases the risk of skin cancer and sunburn. Dermatologists advise people with this disorder to minimize sun exposure, wear eye protection like sunglasses, and use sunscreen regularly.