What part of us is genetically determined ?

What kind a DNA test tell us ?

It is common knowledge that such thing as eye or hair colour, body height, baldness or some diseases are genetically inherited from our parents. Researchers are progressively discovering less obvious facets of our lives that are dictated by our genes. Here is a non-exhaustive list of diseases and traits, most of which can be tested by commerical companies like deCODEme and 23andMe or Navigenics.

Psychology & Neurology

- ADHD (attention-deficit hyperactivity disorder) : linked to novelty-seeking behaviour, anti-conformism, nomadism and food cravings.

- Autism (additional link) or Asperger's Syndrome

- Avoiding errors (capacity of learning from mistakes)

- Bipolar disorder

- Brain-derived neurotrophic factor (BDNF) : better cognitive ability but higher rates of depression.

- Depression

- Dyslexia

- Emotional committment (for long-term relationships)

- Fear, anxiety, and trauma (additional link)

- Faithfulness

- Gambling

- Obsessive-Compulsive Disorder

- Schizophrenia

- Tyranical behaviour and ruthlessness (additional link)

Diseases

- Abdominal Aortic Aneurysm (AAA)

- Intracranial Aneurysm

- Age-related Macular Degeneration

- Alzheimer's Disease

- Amyotrophic Lateral Sclerosis (ALS)

- Ankylosing Spondylitis

- Asthma

- Atrial Fibrillation

- Bladder Cancer

- Breast Cancer

- Colorectal Cancer

- Larynx Cancer

- Lung Cancer

- Oral and Throat Cancer

- Prostate Cancer

- Skin Cancer

- Stomach Cancer

- Coronary Heart Disease

- Celiac Disease

- Crohn's Disease

- Creutzfeldt-Jakob Disease

- Type 1 and 2 Diabetes

- G6PD Deficiency

- Glaucoma

- Gout

- Graves' disease

- Hearing loss (additional link)

- Heart attack risk

- Hemochromatosis

- Kidney Disease

- Kidney stones

- Systemic Lupus Erythematosis (SLE or Lupus)

- Multiple Sclerosis (MS)

- Neuroblastoma

- Nonsyndromic Deafness

- Neurofibromatosis type II (familial brain tumour)

- Osteoarthritis

- Parkinson's Disease

- Peripheral Arterial Disease

- Pre-eclampsia

- Progressive Supranuclear Palsy

- Psoriasis

- Rheumatoid Arthritis

- Sickle Cell Anemia

- Sjögren's Syndrome

- Venous Thromboembolism

Drug response & dependence

- Alcoholism and alcohol cravings (rs1799971)

- Alcohol Flush Reaction

- Antidepressant response (rs2032583)

- Caffeine metabolism speed (rs762551)

- Heroin addiction risk (rs1799971)

- Nicotine Dependence

Immunity and disease resistance

- HLA type (Immune System Compatibility)

- Resistance to HIV and AIDS

- Malaria Resistance (Duffy Antigen)

- Norovirus Resistance

Other medical conditions

- Baldness

- Blood glucose level

- Fertility

- HDL cholesterol level (rs5370)

- High Blood Pressure (Hypertension)

- Lactose intolerance

- Restless Legs Syndrome

- Persistent Fetal Hemoglobin

Senses

- Bitter Taste Perception

- Non-Bitter Taste Perception

- Odor Detection (Smell Sensitivity)

- Pain Sensitivity

Physical performances

- Muscle performance (rs1815739)

- Endurance

- Sprinter type vs running endurance

- Dancer vs non-dancer

Physical traits

- Obesity

- Weight/Body mass index

- Pigmentation (skin, hair and eye colour, freckles)

- Earwax Type

Others

- Circadian Rhythm

- Effect of breast-feeding on IQ

- Left-handedness

- Happiness

- Optimism

- Longevity (additional link)

- Memory

Apart from the obvious benefits of preventive medicine and early detection of a genetically determined disease, a DNA test can be useful to predict the risks for one's children to get rare recessive genetic disease.

Recessive means that a person can be a carrier without exhibiting any symptom. Many genetic diseases need a mutation in a pair of allele. A person with a mutation in only one of the two alleles will be a carrier. If both parents are carriers, the child has 25% chance of getting the disease and 50% of being a carrier too.

Some recessive diseases are more annoying than harmful, such as Colour Blindness (Daltonism). But most are very serious, like light allergy, Haemophilia, Rett syndrome, or Tay-Sachs disease (TSD), and even life-threatening, like Cystic fibrosis (CF).

Genetic tests were too expensive until recently for most people. Now that they are becoming more affordable it should become any future parent's duty to check his/her compatibility with his/her partner before procreating. Couples at risk should seriously envisage assisted procreation, which allows embryos to be tested and filtered for (serious) genetic diseases before being artificially inseminated. No modification to the DNA is involved. It is just a matter of sorting out the various haphazard combinations and get rid of the harmful ones before being allowed to grow in the uterus.

Here is a list of SNP's on chip Illumina Human Hap550 used by 23andMe and on the Illumina Human 1M used by deCODEme.