This genetic disorder is as rare as it is severe. The classic form of the disease, called Hutchinson-Gilford Progeria, causes accelerated aging.
Most children who have progeria essentially die of age-related diseases around the age of 13, but some can live into their 20s. Death is typically caused by a heart attack or stroke. It affects as few as one per eight million live births.
The disease is caused by a mutation in the LMNA gene, a protein that provides support to the cell nucleus. Other symptoms of progeria include rigid (sclerotic) skin, full body baldness (alopecia), bone abnormalities, growth impairment, and a characteristic “sculptured” nasal tip.
2. Uner Tan Syndrome
Uner Tan syndrome is a somewhat controversial condition, whose most obvious property is that people who suffer from it walk on all fours. UTS is a syndrome that was proposed by the Turkish evolutionary biologist Üner Tan after studying five members of the Ulaş family in rural Turkey. These individuals walk with a quadrupedal locomotion, use primitive speech, and have a congenital brain impairment (including “disturbed conscious experience”). The family was featured in a 2006 BBC2 documentary called, "The Family That Walks On All Fours." Tan describes it like this:
The genetic nature of this syndrome suggests a backward stage in human evolution, which is most probably caused by a genetic mutation, rendering, in turn, the transition from quadrupedality to bipedality. This would then be consistent with theories of punctuated evolution.
The new syndrome, says Tan, “may be used as a live model for human evolution.” Some experts think this is bunk, and that genetics may have very little to do with it.
Hypertrichosis is also called “werewolf syndrome” or Ambras syndrome, and it affects as few as one in a billion people; and in fact, only 50 cases have been documented since the Middle Ages.
People with hypertrichosis have excessive hair on the shoulders, face, and ears. Studies have implicated it to a rearrangement of chromosome 8. It happens due to a disruption of the “crosstalk” between the epidermis and the dermis as hair follicles form in the 3-month fetus at the eyebrows and down to the toes. Normally, signals from the dermis send the messages to form follicles. As a follicle forms, it sends signals to prevent the area around it from also becoming a follicle, which results in the equal spacing of our five million or so follicles. Most of our body parts ignore the messages to form follicles, which explains why most of us are relatively hairless.
4. Epidermodysplasia Verruciformis
Epidermodysplasia verruciformis is an extremely rare disorder that makes people prone to widespread human papillomavirus (HPV) infection. This infection causes scaly macules and papules (cutaneous squamous cell carcinomas) to grow on the hands, feet, and even face. These skin “eruptions” appear as wart-like lesions — and even wood-like and horn-like growths — with reddish-brown pigmented plaques. Typically, the skin tumors start to emerge in people between the age of 20 and 40, and the growths tend to appear on areas exposed to the sun. Also called Lewandowsky-Lutz dysplasia, there is no known cure, though treatments to scale back the growths are possible.
The disorder was brought to the public’s attention in November 2007 when a video of a 34-year-old Indonesian man named Dede Koswara appeared on the internet. In 2008, he underwent surgery to have 13 pounds (6 kg) of the warts removed. After the lesions and horns were extracted from his hands, head, torso, and feet, his hands were grafted with new skin. In all, about 95% of the warts were removed.
5. Severe Combined Immunodeficiency Disorder (SCID)
The disease was made famous by virtue of the 1976 film, The Boy in the Plastic Bubble, a story inspired by the lives of David Vetter and Ted deVita. In the movie, a boy is forced to live in plastic isolation for fear of exposure to unfiltered air and the introduction of life-threatening pathogens. In real life, Vetter lived in this condition for 13 years, but he died in 1984 following an unsuccessful bone marrow transplant (a failed attempt to help him fight infections).
And indeed, the disorder is caused by a number of genes, including those that cause defects in both T and B cell responses — which has a downstream negative effect on the production of lymphocytes (a type of white blood cell). SCID is also thought to arise due to the lack of adenosine deaminase (ADA). Interestingly, SCID was the first human illness treated by human gene therapy in 1990, and is increasingly being used to treat children. Image: Baylor College of Medicine Archives.