Alcohol Flush Reaction
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Alcohol flush reaction is a condition in which an individual's face or body experiences flushes or blotches as a result of an accumulation of acetaldehyde, a byproduct of the catabolic metabolism of alcohol.
This reaction is usually experienced by people of East Asian descent - according to the analysis by HapMap project the allele of the ALDH2 gene responsible for this reaction is rare among Europeans and Africans, very rare among Mexican-Americans but quite common among people of Chinese and Japanese ancestry.
More information on Alcohol Flush Reaction:
Research papers:
- Yoshida et al.(1984). "Molecular abnormality of an inactive aldehyde dehydrogenase variant commonly found in Orientals" Proc Natl Acad Sci U S A. 81(1):258-61
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Bitter Taste Perception
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Not all humans have the same perception of bitterness - a genetic variation in TAS2R38 gene prevents some people from tasting propylthiouracil (PROP) - a compound often found in cabbage, raw broccoli, coffee and dark beers. About 25% of people lack ability to detect this compound due to gene mutations and they find most food and drink to be less bitter, or not bitter at all.
More information on Bitter Taste Perception:
Research papers:
- Kim et al.(2003). "Positional cloning of the human quantitative trait locus underlying taste sensitivity to phenylthiocarbamide" Science. 299(5610):1221-5.
- Drayna et al.(2005). "Human taste genetics." Annu Rev Genomics Hum Genet 6:217-35
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Earwax type
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Some people have earwax that is wet, sticky and yellow or brown; other people's earwax is dry, crumbly and grayish.
The type of earwax is determined by a variation at a single gene (ATP-binding cassette C11 gene), with the 'wet earwax' allele being dominant over the 'dry earwax' one.
More information on Earwax type:
Research papers:
- Yoshiura et al. (2006). "A SNP in the ABCC11 gene is the determinant of human earwax type." Nature Genetics 38(3):324-30.
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Lactose intolerance
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Lactose intolerance is the inability to digest lactose, a sugar found in milk and in some milk-derived dairy products.
Lactose intolerant individuals have insufficient levels of lactase, the enzyme that metabolizes lactose into glucose and galactose, in their digestive system. This condition is quite common in adults and is not dangerous, but has unpleasant symptomes such as abdominal bloating and cramps, flatulence, diarrhea or nausea after consuming significant amounts of dairy products.
More information on Lactose intolerance:
Research papers:
- Enattah et al. (2002). "Identification of a variant associated with adult-type hypolactasia." Nat Genet. 2002 Feb;30(2):233-7.
- Bersaglieri et al. (2004). "Genetic signatures of strong recent positive selection at the lactase gene." Am J Hum Genet. 2004 Jun;74(6):1111-20.
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Eye color
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The pigmentation of the iris in humans varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris). In conjunction with white collagen fibers it produces different shades of grey, green and hazel.
Eye color is an inherited polygenic trait, influenced by more than one gene - there is evidence that as many as 16 different genes could be responsible for eye color in humans - yet studies show that it is possible to predict eye color with enough accuracy by using only 6 SNPs.
More information on Eye color:
Research papers:
- Walsh et al. (2013). "The HIrisPlex system for simultaneous prediction of hair and eye colour from DNA." Forensic Sci Int Genet. 2013 Jan;7(1):98-115
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Hair color
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Hair color is determined by the amount of two pigments - brown-black eumelanin predominates in black and brown hair and red-yellow pheomelanin in red hair. Blond hair contains low levels of both pigments.
The genetics of human hair color are not firmly established yet, but there are indications that multiple genes determine whether a person will have brown, blond or red hair.
More information on Hair color:
Research papers:
- Walsh et al. (2013). "The HIrisPlex system for simultaneous prediction of hair and eye colour from DNA." Forensic Sci Int Genet. 2013 Jan;7(1):98-115
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Breast size
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Breast size is moderately heritable and recent studies has identified a number of single-nucleotide polymorphisms (SNPs) significantly associated with breast size. These studies provide insight into the genetic factors underlying normal breast development and show that some of these factors are also shared with probability of having breast cancer.
Average cup size:C Research papers:
- Eriksson et al. (2012) "Genetic variants associated with breast size also influence breast cancer risk." BMC Med Genet
Average cup size:C |
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Cleft Lip/Palate
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Cleft lip and cleft palate are variations of a type of clefting congenital deformity caused by abnormal facial development. Approximately 1 in 700 children born have a cleft lip and/or a cleft palate.
Cleft lip is formed in the top of the lip as either a small gap or it continues into the nose. Cleft palate is a condition in which the two plates of the skull that form the hard palate are not completely joined.
Population average: 0.1%
More information on Cleft Lip/Palate:
Research papers:
- Beaty et al. (2010) "A genome-wide association study of cleft lip with and without cleft palate identifies risk variants near MAFB and ABCA4." Nat Genet
Population average: 0.1% |
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Male Pattern Baldness
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Male Pattern Baldness is the most common cause of hair loss in men. In classic pattern baldness, hair is lost in a well-defined pattern, beginning above both temples. Hair also thins at the crown of the head. Often a rim of hair around the sides and rear of the head is left.
Average Lifetime Risk: 50% Men
More information on Male Pattern Baldness:
Research papers:
- Li et al. (05-31-2012) "Six novel susceptibility Loci for early-onset androgenetic alopecia and their unexpected association with common diseases." PLoS Genet
Average Lifetime Risk: 50% Men |
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Spot baldness
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Alopecia Areata is a medical condition in which hair is lost from some or all areas of the body, usually from the scalp. It causes bald spots on the scalp, especially in the first stages. In some cases, the condition can spread to the entire scalp or to the entire epidermis.
Average Lifetime Risk: 1.7%
More information on Spot baldness:
Research papers:
- Petukhova et al. (2010) "Genome-wide association study in alopecia areata implicates both innate and adaptive immunity." Nature 466(7302):113-7
Average Lifetime Risk: 1.7% |
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Tanning Ability
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Freckles
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Freckles are clusters of concentrated melaninized cells which are most easily visible on people with a fair complexion. The formation of freckles is triggered by exposure to sunlight - the exposure to UV-B radiation activates melanocytes to increase melanin production, which causes freckles to become darker and more visible. Although freckles are usually found on the face, they may also appear on any skin exposed to the sun, such as arms or shoulders.
More information on Freckles:
Research papers:
- Eriksson, Nicholas et al. "Web-Based, Participant-Driven Studies Yield Novel Genetic Associations for Common Traits." Ed. Greg Gibson. PLoS Genetics 6.6 (2010): e1000993.
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Acne
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Acne vulgaris (acne) is a common inflammatory skin disorder that occurs when hair follicles are clogged with dead skin cells and oil from the skin. Acne is characterized by areas of blackheads, whiteheads, pimples, and greasy skin, and may result in scarring.
Genetics is thought to be the cause in about 80% of cases, while the remaining 20% are attributed to health, lifestyle and environment factors.
80-90% of teenagers
More information on Acne:
Research papers:
- Navarini A.A. et al. (2014) "Genome-wide association study identifies three novel susceptibility loci for severe Acne vulgaris." Nat. Commun. 5:4020 doi: 10.1038/ncomms5020
80-90% of teenagers |
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Ear protrusion
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Prominent, or protruding ears are an inherited problem affecting 1-2% of the population. Prominent ears do not tend to improve and about 30% of babies who have prominent ears are born with normal-looking ears with the problem only arising in the first three months of life. There are no functional problems associated with prominent ears, but they may cause considerable psychological distress.
More information on Ear protrusion:
Research papers:
- Adhikari, Kaustubh et al. "A Genome-Wide Association Study Identifies Multiple Loci for Variation in Human Ear Morphology." Nature Communications 6 (2015): 7500.
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Ear lobe attachment
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Most humans have ear lobes detached, but in some cases the lower lobe is connected to the side of the face.
More information on Ear lobe attachment:
Research papers:
- Adhikari, Kaustubh et al. "A Genome-Wide Association Study Identifies Multiple Loci for Variation in Human Ear Morphology." Nature Communications 6 (2015): 7500.
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Blood Type (ABO)
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The ABO system is the most important blood-group system in human blood transfusion.
ABO types are classified by presense and absense of associated anti-A and anti-B antibodies. Presense of these antibodies is encoded by one genetic locus, the ABO locus, which has three alternative forms:A, B, and O. A child receives one of the three variants from each parent, giving rise to six possible genotypes and four possible blood types.
More information on Blood Type (ABO):
Research papers:
- Satoh K., Itoh, Y.(2006). "Forensic ABO blood grouping by 4 SNPs analyses using an ABI PRISMR3100 genetic analyzer." International Congress Series 1288:49-51
- Sung Ho Lee et al.(2009). "Rapid ABO Genotyping Using Whole Blood without DNA Purification." Korean J Lab Med 2009;29:231-7
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Cholesterol, HDL
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High-density lipoprotein (HDL, "Good Cholesterol") is one of the five major groups of lipoproteins that enable lipids like cholesterol and triglycerides to be transported within the water-based bloodstream. In healthy individuals, about thirty percent of blood cholesterol is carried by HDL.
HDL particles are able to remove cholesterol from within artery atheroma and transport it back to the liver for excretion or re-utilization. People with higher levels of HDL seem to have fewer problems with cardiovascular diseases, while those with low HDL cholesterol levels have increased rates for heart disease.
Average: 55 mg/dL Research papers:
- Teslovich et al. (2010) "Biological, clinical and population relevance of 95 loci for blood lipids." Nature
- Ridker et al. (2009) "Polymorphism in the CETP gene region, HDL cholesterol, and risk of future myocardial infarction: Genomewide analysis among 18 245 initially healthy women from the Women's Genome Health Study." Circ Cardiovasc Genet
- Willer et al. (2008) "Newly identified loci that influence lipid concentrations and risk of coronary artery disease." Nat Genet
Average: 55 mg/dL |
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Cholesterol, LDL
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Low-density lipoprotein (LDL, "Bad Cholesterol") is one of the five major groups of lipoproteins that enable lipids like cholesterol and triglycerides to be transported within the water-based bloodstream.
Studies have shown that higher levels of type LDL particles correlate with much faster growth of atheroma, progression of atherosclerosis and earlier and more severe cardiovascular disease events.
Average: 115 mg/dL Research papers:
- Teslovich et al. (2010) "Biological, clinical and population relevance of 95 loci for blood lipids." Nature
- Willer et al. (2008) "Newly identified loci that influence lipid concentrations and risk of coronary artery disease." Nat Genet
Average: 115 mg/dL |
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Cholesterol, Total
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Cholesterol is an organic chemical substance classified as a waxy steroid of fat. Although cholesterol is important and necessary for human health, high levels of cholesterol in the blood have been linked to damage to arteries and cardiovascular disease.
The Cholesterol levels include:
- LDL (low-density lipoprotein cholesterol, 'bad' cholesterol)
- HDL (high-density lipoprotein cholesterol, 'good' cholesterol)
- Triglycerides (fats carried in the blood)
Average: 210 mg/dL
Average: 210 mg/dL |
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Triglycerides
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In humans, triglycerides are a mechanism for storing unused calories, and their high concentration in blood correlates with the consumption of starchy and other high carbohydrate foods.
High levels of triglycerides in the bloodstream have been linked to atherosclerosis and the risk of heart disease and stroke.
Average: 144 mg/dL Research papers:
- Teslovich et al. (2010) "Biological, clinical and population relevance of 95 loci for blood lipids." Nature
- Willer et al. (2008) "Newly identified loci that influence lipid concentrations and risk of coronary artery disease." Nat Genet
Average: 144 mg/dL |
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Resting heart rate
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Heart rate is the number of heartbeats per unit of time, usually expressed as beats per minute (bpm). Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during physical exercise or sleep. The typical resting heart rate in adults is 60 to 100 bpm. Resting Heart Rates below 60 bpm may be referred to as bradycardia, while rates above 100 bpm at rest may be called tachycardia.
Average: 67 bpm Research papers:
- Eijgelsheim et al. (2010) "Genome-wide association analysis identifies multiple loci related to resting heart rate." Hum Mol Genet
Average: 67 bpm |
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Caffeine Consumption
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Caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, soft drinks, and energy drinks, enjoy great popularity; 90% of adults consume caffeine daily. Ordinary consumption has low health risks, but consumption of large amounts of caffeine can lead to both positive and negative effects.
Average: 280 mg/day
More information on Caffeine Consumption:
Research papers:
- Amin et al. (2011) "Genome-wide Association Analysis of Coffee Drinking Suggests Association with CYP1A1/CYP1A2 and NRCAM." Mol Psychiatry 10.1038/mp.2011.101
- Sulem et al. (2011) "Sequence variants at CYP1A1-CYP1A2 and AHR associate with coffee consumption." Hum Mol Genet. 20(10):2071-7
- Cornelis et al. (2011) "Genome-wide meta-analysis identifies regions on 7p21 (AHR) and 15q24 (CYP1A2) as determinants of habitual caffeine consumption."PLoS Genet. 7(4):e1002033
Average: 280 mg/day |
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Smoking Behavior
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There are many social and environmental factors that affect whether people start smoking, but genetic factors play a significant part in how dependent on nicotine they'll become and how much they'll smoke.
Average: 14 cigarettes/day
Average: 14 cigarettes/day |
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