Buzz
Our perception of what it means to be human is often quite rigid. We envision beings with a head, two arms, two legs, five fingers, and so on. However, there are individuals who defy these expectations, yet remain undeniably human. While we might encounter such cases online, it’s often hard to tell if they’re authentic. So, here are ten rare mutations that stretch the limits of our understanding of what it means to be human, supported by scientific evidence.
10. Anencephaly
When we come across stories of ‘Frog Babies’ in the news, we may dismiss them as fabrications, but the only inaccuracy lies in the sensational label. This rare condition, known as anencephaly, is a neural tube defect. Typically, the neural tube closes between the third and fourth week of pregnancy, allowing the brain and spinal cord to form. In babies with anencephaly, the neural tube fails to close fully, exposing the brain to amniotic fluid, which accelerates the breakdown of neural tissues. The brains of affected babies often lack portions of the skull, along with the cerebrum and cerebellum, leading to blindness, deafness, and an inability to attain consciousness. Unfortunately, these babies are generally stillborn or pass away within a few weeks.
Anencephaly is an exceptionally rare condition, affecting approximately three in every 10,000 births. However, after one child is born with anencephaly, the likelihood of having another child with the same condition increases to 3-4%, and if two children are affected, the chances rise to 10-13%. Hispanic mothers are found to be at a higher risk, although the cause remains unknown. Anencephaly has been linked to a deficiency in B9 or folate. Supplementing with folic acid, the synthetic form of folate, can lower the risk by up to 50%. During pregnancy, anencephaly can be detected through imaging, excess amniotic fluid, or elevated levels of alpha-fetoprotein. Unfortunately, there is no known cure for this condition.
9. Ectrodactyly
This condition, often referred to as “lobster claw,” and sometimes mistakenly called “ostrich foot,” can be explained through the example of certain animals. Ectrodactyly, caused by mutations in chromosomes 10, 7, 3, or 2, is an X-linked condition that results in split hands and feet. There are two main forms of ectrodactyly. In type one, the middle digit is absent, and a significant cleft runs through the middle of the hand or foot. Webbing may also be present between the digits. Type two is characterized by the presence of only the fifth digit and the absence of a cleft. Occasionally, individuals may exhibit both forms within a family. There are both syndromic and nonsyndromic types, but aside from these variations, individuals with ectrodactyly typically have normal intelligence and lifespan.
Ectrodactyly is predominantly a dominant autosomal disorder, meaning that only one mutated gene is needed to inherit the condition. There is a 50% chance of passing the mutation on to a child, regardless of the child’s gender. However, in some cases, the condition has been found to be recessive autosomal. This disorder affects roughly 1 in 18,000 people, with diagnosis typically made at birth. X-rays can help provide further details on the specific presentation of the condition. For those affected, reconstructive surgery is available in some cases, and prosthetics may enhance functionality.
8. Epidermodysplasia Verruciformis
Often referred to as “Tree Man Disease,” Epidermodysplasia verruciformis (EV) is a rare and complex disorder that has nothing to do with trees. This autosomal recessive skin condition arises only when both parents carry the gene. EV is an extremely rare disorder that primarily affects the skin.
Around 10% of EV cases occur in children born to parents who are related by blood. The onset of symptoms typically begins in childhood, with 7.5% of cases appearing in infancy, 61.5% between the ages of 5-11, and 22.5% during adolescence. The condition appears to affect both genders and all races equally.
Epidermodysplasia verruciformis manifests as skin lesions caused by the human papillomavirus (HPV). Those with EV struggle to mount an effective immune response, leading to the appearance of lesions. These lesions can take the form of flat-topped, pink to violet papules or larger, reddish-brown, scaly plaques. Papules typically appear on the hands, feet, face, and earlobes, while plaques are more common on the torso, neck, and limbs, though they can occur anywhere on the body. Exposure to sunlight can cause these lesions to become cancerous, and the risk of this depends on the specific type of HPV the patient is infected with. Various treatments have been explored, with lesion extraction proving to be more effective than oral or topical therapies. Surgical removal is another option. At present, there is no preventative cure for EV.
7. Diprosopus
Diprosopus, or craniofacial duplication, is an extremely rare disorder that results in the duplication of facial features, and in some cases, the cerebral frontal lobes. The condition is believed to stem from a protein called sonic hedgehog homolog, which is linked to a specific gene. Sonic hedgehog proteins play a crucial role in signaling cells to correctly form organs and limbs during fetal development, and the one associated with diprosopus is believed to affect the patterning of the face and brain.
This condition can also lead to conjoined twins with two faces, though their bodies are not fully separated. These twins typically have a near-complete fusion of their bodies and share one set of limbs. Part or all of the face may be duplicated. Unfortunately, diprosopus usually results in stillbirth. There are only around 36 recorded cases of this rare genetic mutation. A deficiency in sonic hedgehog protein can cause another condition listed here.
A notable case occurred in the United States in 2004. Tres Johnson, who celebrated his 13th birthday in 2017, is a rare survivor of diprosopus. Doctors initially predicted he wouldn't survive to see another stage of life. In 2008, a baby girl named Lali Singh was born in India with two fully formed faces. She became a media sensation in her small village. Tragically, she passed away from a heart attack two months after birth.
Diprosopus is not exclusive to humans—it has also been observed in animals. While cats with diprosopus typically don't survive long due to related health complications, two cats named Frank and Louie defied the odds and earned a place in the 2012 Guinness World Records. These cats are often referred to as Janus cats, after the Roman god who was depicted with two faces.
6. Polymelia
While many of us might daydream about having an extra arm, those born with additional limbs often wish they didn't. Polymelia is a rare disorder where individuals are born with extra lower limbs. These accessory limbs are often not fully developed, though they usually contain bones and blood vessels. While more common in animals, polymelia is exceedingly rare in humans, with very few documented cases.
There are different types of polymelia based on the location of the extra limb. In Cephalonia, the extra limb is positioned on the head, while in notomelia, it is attached to the spine. Thoracomelia refers to extra limbs attached to the chest, and pyromelia involves extra limbs at the pelvis. Polymelia can be triggered by factors like thalidomide or hormone drugs. The condition can be detected as early as four or five weeks of embryonic development, and it can also occur due to the incomplete separation of twins. Surgery is often required to remove the extra limbs.
5. Progeria
When elderly people claim they feel like they were children only yesterday, they mean it metaphorically. But for those suffering from progeria, which translates from Greek to 'premature aging,' it’s the literal truth. Progeria is a life-threatening condition that causes rapid aging, with symptoms appearing as early as two years old. Tragically, most individuals with progeria pass away from heart disease by the time they reach fourteen.
Progeria leads to accelerated aging in children and is marked by distinct physical traits. Common features include large, prominent eyes, a small chin, a small nose, and large ears. Additionally, children with progeria often have skin that appears aged, along with bone and heart problems, and a loss of subcutaneous fat. Despite these challenges, their motor skills and cognitive abilities typically remain unaffected.
Progeria is thought to affect approximately 1 in every 4 to 8 million infants. While there is no cure, treatments are available to manage symptoms. Exercise and dietary adjustments can help address lipid imbalances, and shoe padding can provide comfort while walking. Depending on the conditions that arise, heart treatments, such as nitroglycerin, are often prescribed. Joint therapy is also beneficial, and using sunscreen is recommended to prevent skin issues.
4. Proteus
Those with proteus are truly exceptional. This rare condition, known as proteus syndrome, involves abnormal growth affecting bones, skin, organs, and other tissues. People with proteus commonly develop benign tumors, and the condition affects the body unevenly, meaning one side may be more affected than the other. Blood vessels and veins may also be impacted, and those with proteus are at higher risk for deep vein thrombosis (DVT), which can lead to pulmonary embolism, the leading cause of death in these individuals. In some cases, intellectual disability or seizures may also occur. People with proteus may exhibit distinct physical features, such as a long face, eyes with downward sloping outer corners, and wide nostrils.
Individuals with proteus may also experience the development of lesions. These can range from rough, dark lesions present at birth to thickened, firm skin with grooves or furrows, particularly on the feet and occasionally the hands. Proteus can lead to various tumors, including bilateral ovarian cystadenomas, monomorphic adenomas, meningiomas, and tumors or cysts in the eyes. Crossed eyes can also be a possible manifestation. Additionally, enlarged organs may result in kidney or urinary complications.
Proteus is not inherited and is not influenced by environmental factors. It occurs due to a mutation in the AKT1 gene in a single cell during the early stages of development. This gene regulates cell growth, division, and death. As the mutated cell divides, the mutation spreads in a random pattern known as 'mosaicism,' which causes the condition to manifest unevenly throughout the body. Typically, a newborn appears normal at birth, but the overgrowth symptoms begin to emerge between six and eighteen months of age. Proteus is extremely rare and doesn't appear to follow a family history. The likelihood of a sibling developing proteus is just 1%, and parents with proteus have not been known to pass it on.
3. Polycephaly
What if we had to share our body with another person? Individuals with polycephaly, or two heads, experience this scenario firsthand. Polycephaly is a rare and severe form of conjoined twins, occurring in about 1 in 50,000 to 200,000 pregnancies. The development of polycephaly depends on how completely the twins separate and if they later fuse. Typically, these individuals are regarded as two people, yet they usually share vital organs and each controls only half of the limbs. In human cases, polycephalic people often have the coordination to walk, run, and even drive. Sometimes, one head is parasitic, functioning minimally or not at all. Attempts to surgically remove the parasitic head have generally proven ineffective, and most polycephalic individuals do not survive.
2. Cyclopia
Many of us are familiar with the myth of the cyclops, whether from Homer’s *Odyssey* or other ancient works of literature. These creatures were likely inspired by a rare medical condition now known as cyclopia. Cyclopia occurs when an individual is born with one central eye or two undivided eyes. Often, the person lacks a nose but has a structure above their eye resembling a nose. This condition is seen in about 1 in 100,000 births. Cyclopia is classified as alobar holoprosencephaly, the most severe of the three types. It can be detected prenatally through ultrasound or sonography. Most babies with cyclopia are either stillborn or aborted, and those who survive birth typically pass away shortly thereafter due to the fatal nature of the condition and its related complications.
1. Sirenomelia
While mermaids are often depicted in fiction with fish-like features, those born with the condition known as mermaid syndrome do not match the mythical image. Officially referred to as sirenomelia, this condition occurs when a baby is born with a single lower limb. Sirenomelia is an extraordinarily rare condition, with only 300 documented cases in medical literature. Of these cases, 15% were part of identical twin pairs, and 22% were born to mothers with diabetes. The prevalence is estimated at about 1 in 60,000 to 100,000 births. Although it affects all ethnicities, it is more commonly found in males, with a male-to-female ratio of approximately 2.7:1. The majority of infants with sirenomelia do not survive past infancy, although some have managed to live into young adulthood after undergoing reconstructive surgery.
Sirenomelia is thought to be multifactorial, meaning that both genetic and environmental factors may contribute to its development. In some cases, there is only one artery supplying blood to the lower portion of the embryo, resulting from the absence of the two arteries branching from the aorta. This leads to insufficient nutrient supply to the lower part of the embryo, causing its underdevelopment. Sirenomelia is more prevalent in babies born to mothers with diabetes, with about 22% of infants affected by this condition having diabetic mothers. Children with sirenomelia often also suffer from spinal deformities, gastrointestinal issues, and underdeveloped lungs, the latter of which is a frequent cause of death in affected individuals.
Sirenomelia is classified into seven types based on the degree of development of the lower limbs. Type one involves the presence of all necessary bones for the legs, with only skin connecting the limbs. The other types progressively worsen, with type seven being the most severe, where the 'leg' consists of only a single bone.
