50 Fascinating Facts about DNA and Genes – Part 2

About 55% of all pregnancies end in miscarriage, most often before a woman misses a menstrual period or even knows she is pregnant. More than 80% of miscarriages occur within the first three months of pregnancy. This is mostly caused by chromosomal abnormalities.

27. In 1962, scientists discovered a limit to how many times human cells can divide before they become exhausted. They also discovered telomeres, which cap the ends of chromosomes and prevent them from fraying. Telomeres shorten each time a cell divides and when they get short enough, a cell stops dividing.

28. While female X chromosomes get mixed and reshuffled, Y chromosomes get passed down untouched, resulting in the grandfather, father, and son having identical Y chromosomes.

29. Complete Androgen Insensitivity Syndrome causes a person with XY chromosomes externally to develop to be identical to XX girls/women. A vagina is present but no uterus. It is often undetected until a lack of first menstruation is noted.

30. One of the leading hypotheses on why asbestos causes cancer is that it’s extremely thin fibers get physically tangled in your chromosomes, leading to strand breaks and mutations.

Exposure to particles from burning candles causes greater damage than the same dose of diesel exhaust fumes. Effects included lung inflammation and toxicity, arteriosclerosis, and aging effects on chromosomes in the lungs and spleen.

32. The Y chromosome has been degenerating over the past 300 million years of its existence, and might one day go extinct. The male gender, however, probably won't.

33. 50-60% of drug addiction risk is genetically inherited.

34. Ectopia Cordis is a rare genetic defect that develops in fetuses in utero. Their chest wall doesn't form correctly. It also doesn't fuse as it normally would. This prevents the heart from developing where it should, leaving it defenseless and exposed. 90% of babies don't survive. 

35. Alana Saarinen is a girl with 3 biological parents. Alana’s nuclear DNA is from her mother and father, with mitochondrial DNA from another woman. This procedure has now been banned due to safety and ethical concerns.

The chances of you being you, taking into account eggs, sperm, ancestry, etc., is equivalent to 2 million people each rolling a trillion-sided die, and each person rolling precisely the same number (approximately 1 in 10^2,685,000).

37. Every fetus is a female in the uterus until receiving the “Y” chromosome. If the sperm has a Y chromosome, your baby will be a boy. If it has an X chromosome, the baby will be a girl. If it is a boy, in the further stages of fetal development, when the testosterone kicks in, the cells begin to change in the genitals, but the nipples remain. That's why men have nipples.

38. Color blindness is carried on the "X" chromosome. Since women have two of them, they won't be colorblind as often as men who only have one.

39. Snatiation is a genetically-transmitted condition in which people sneeze after eating a meal and becoming full.

40. Random testing has shown that far more British people carry the Mad Cow Disease prion than have shown symptoms, which is roughly 1 in 2000. The absence of symptoms is thought to be linked to genetics.

X-linked Dystonia-Parkinsonism is an adult-onset genetic movement disorder that affects individuals who descend from the Philippine Island of Panay. It is a neurodegenerative disease that evolves over many years, resulting in significant disability and a shortened life span.

42. In 1990, Dr. Mary-Claire King discovered the human gene BRCA1 which is linked to breast cancer. Soon after, Myriad Genetics cloned and patented it. She was sent a cease-and-desist letter to stop researching it. Finally, in 2013, the US Supreme Court ruled that human genes cannot be patented.

43. Danny DeVito’s height is the result of Fairbank’s Disease, a rare genetic disorder that affects bone growth.

44. Lactose tolerance is a genetic mutation where a cytosine (C) nucleotide in a person's DNA is replaced with thymine (T) nucleotide which allows them to digest milk.

45. Darwinian theory has no explanation for why a species with mating rituals do not completely lose all-male genetic variants since females are only attracted to certain specific male characteristics. This is known as the Lek paradox.

8% of our DNA consists of remnants of ancient viruses, and another 40% is made up of repetitive strings of genetic letters that are also thought to have that origin.

47. Genetic Sexual Attraction is sometimes seen between “close blood relatives who have been separated during the critical years of development and bonding and are reunited after as adults.”

48. The skin on the body of a boy named Hassan looks like an open wound because of a genetic condition that led to his skin to be paper-thin. For treatment doctors took his skin sample, repaired his DNA, and the modified skin cells were grown to make skin grafts totaling 0.85 sq m. He now leads a normal life.

49. Between 14-21% of the population have a genetic variation known as Linburg-Comstock syndrome. This variation inhibits the ability to bend your thumb without also bending your pointer finger.

50. Xeroderma pigmentosum (XP) is a rare genetic condition that makes the sun’s rays lethal. Up to one in 370 Indians suffer from a genetic condition that causes the skin to burn and take on a blistering, scaly appearance. With exposure to the sun, XP damages the cornea which leads to blindness.