The Lottery Of Life

Eighth instalment - yet more heritable traits

In the previous two instalments I have set out the argument (which I trust you have found reasonable and convincing) that an individual’s sex and skin colour are determined almost entirely by genetic inheritance; and that an individual’s sex and skin colour, while not predictive of a particular outcome in life, do profoundly affect the extent to which the individual will be advantaged or disadvantaged throughout life.

Male and white? You’re off to flying start in the lottery of life. Female and black? Not so much.

Everyone has a sex and a skin colour. However the packages of DNA that your parents gifted to you by means of chromosomes may contain other traits that are highly heritable and that you cannot escape manifesting. Some of these – the colour of your eyes, the curliness of your hair, for instance – are more or less benign; but many are very far from benign.

In this instalment I’ll discuss heritable conditions and diseases. It’s not going to be comfortable reading. Sod it, I’ll just list them. The three most usually cited are:

  • Cystic fibrosis. This causes the build-up of sticky mucus in the gas exchange and the digestive system. This causes infections in the lungs and makes it difficult to digest food. There is currently no cure. People with cystic fibrosis have a shorter than average life expectancy.
  • Sickle-cell disorder. This results in red blood cells with a sickle or crescent shape. These cells do not live as long as normal cells, can carry less oxygen to the body’s organs and can cause blockages in blood vessels. If these blockages are in the brain or heart, this can cause a stroke or heart attack. Sickle-cell disorder is more common in people with African or Caribbean backgrounds. The only cure is a bone marrow transplant, but this is a risky medical procedure. People with sickle-cell disorder have a shorter than average life expectancy.
  • Haemophilia, which stops the blood clotting. People with haemophilia may have nosebleeds and bruises that last for a long time and have cuts that heal slowly. There is no cure for haemophilia.

In addition to these, Wikipedia lists the following conditions as common:

          Angelman syndrome; Canavan disease; Charcot–Marie–Tooth disease; Colour blindness; Cri du chat syndrome; DiGeorge syndrome; Down syndrome; Duchenne muscular dystrophy; Familial hypercholesterolemia; Haemochromatosis type 1; Klinefelter syndrome; Neurofibromatosis; Phenylketonuria; Polycystic kidney disease; Prader–Willi syndrome; Scheuermann’s disease; Spinal muscular atrophy; Tay–Sachs disease; Turner syndrome.

I have no idea what most of those are, but they don’t sound pleasant.

Wikipedia lists a total of 314 named conditions. These include some that are widely known, such as Crohn’s Disease and Huntington’s Disease, and many that I and most people have never heard of. Some have curious names, such as Cat Eye Syndrome, which sound quite charming until you discover the list of its effects.

Several sources suggest that there are as many as 6000 hereditary conditions, and that about half the population has at least one – although many have relatively mild effects or manifest only late in life. For instance I have been diagnosed with hip dysplasia, which is probably congenital; it has become apparent only recently and so far has had little effect, but as I age it may encourage osteoarthritis and cause me pain.

All of the diseases and conditions that I have discussed so far are attributable entirely to chromosomes and/or the DNA they carry. In some cases the condition will appear only if both parents contribute the relevant gene; in others one parent’s genes are enough. In some cases the condition will appear only if the package of genes inherited by the individual contains several different genes, each of which would be harmless without the others.

The significant point is this: an individual’s genetic inheritance may include a gene or genes that manifest as a disease or condition that, either from birth or later in life, has an effect that may be permanently debilitating, life-changing, or life-shortening. And it’s just a matter of luck.

In addition to the diseases and conditions that can confidently be ascribed to genetic inheritance alone, there are many more that probably have a genetic component but are also effected by environment and lifestyle: asthma, autoimmune diseases such as multiple sclerosis, cancers, ciliopathies, cleft palate, diabetes, heart disease, hypertension, inflammatory bowel disease, intellectual disability, mood disorder, obesity, and infertility – to name just the most common.

The conclusion I arrive at is that all of us have, encoded in our genes, imperfections. An individual might have few or many; he or she might have conditions that are mild or easily corrected, such as myopia, or conditions that are disabling or life-threatening. Few and mild: good luck. Many or severe: bad luck.

In the next instalment – or perhaps the one after next – I’ll look at more traits that have some genetic component.

You’re not yet born; you’re not yet even a foetus; but you have already been dealt three cards: your sex; your skin colour; and your hereditary disease or condition (or lack thereof).

The only way to deal with an unfree world is to become so free that your very existence is an act of rebellion.