Down Syndrome

The culprit- 'bad chromosome'

As my regular readers are aware, I'm a professional human geneticist. I reached the profession, via a tortuous route, many years ago. Prior to working in a genetics lab, I was a botanist. I couldn't make the transition these days, my background and degrees are all wrong. Arse.

Yesterday, I gave a talk to my colleagues and peers about Down syndrome. Most folk have heard of Down syndrome. It is the most common of the chromosome disorders and is caused by an additional chromosome 21 raising the human chromosome complement from 46 to 47. The presence of the extra 300 genes causes disruption to normal embryogenesis resulting in the stigmata associated with typical Down syndrome, and of course the intellectual deficit.  

Down syndrome individuals are instantly recognisable. There is a collective ‘look’ about them that’s not just confined to their highly distinctive facial features. You could identify a Down syndrome person from behind, I’m sure, without seeing their face. Their gait, their whole habitus, is instantly discernable.

They suffer from a whole host of medical problems due to that pesky extra chromosome. Congenital heart disease and other organ defects are common. There is also an increased incidence of leukaemia and an inherent predisposition to other conditions. The thrust of my lecture was concerned with the phenomenon of premature ageing and Down syndrome; tis a well described feature of the condition.

Ageing is a strange disease and we are still not sure why it occurs. We don’t all age at the same rate. I’m not talking chronological age, but biological age. Clearly, ageing is a complex choreography between our genetics and the way we choose to live our lives. Genetics plays a greater role than most doctors let on to their patients. I suppose this is a ‘trick’ to make us live healthy lives, but in most instances the tactic fails miserably. But regardless, some of us are genetically favoured and some less so. Down syndrome individuals fall conclusively into the latter category. Not only do they age faster than the general population, they also have reduced life expectancy. With old age come the diseases of old age. Arthritis and degenerative physical disease come to the fore. We become less mentally acute and are prone to the neurodegenerative diseases, such as Alzheimer’s. Thus is the great pageant which is life (bugger nuts). Down’s individuals experience all this, but earlier.

Life expectancy in the civilised world has been climbing steadily over the past 100 years, and in parallel, the life expectancy for the Down’s population has soared. In 1929 live expectancy was 9 years, whilst today it is closer to 60. Better health and medical care are the likely causes. Although, I suspect in times of yore, infanticide was overtly or covertly practiced.

The incidence of Down syndrome is on the wane. This is due to improvements in prenatal screening. Theoretically, at least, and in the ‘ideal’ hospital setting 90% of Down’s pregnancies can be identified by a maternal blood test together with a detailed ultrasound scan. This is a screening test with many false positives and the definitive diagnosis still requires an invasive test and an examination of foetal chromosomes.  Most women choose to terminate when confronted with a foetus with a chromosomal disorder. And let’s be honest, who can blame them.

Over recent years, Down syndrome advocacy groups have arisen. They argue that Down syndrome individuals can lead happy and fulfilling lives. This cannot be denied. From my experience, parents choosing to terminate a Down's pregnancy are devastated. Terminating life should never be easy. The fact that most couples decide to terminate reflects reality. Raising and caring for a Down syndrome child is  exacting, draining, and emotionally and economically punishing. Their potential child will never live a full and independent life, and they know it.

The extreme end of the Down syndrome advocacy group use highly charged emotional terms and arguments not rooted in fact, or reality. Some argue that to terminate a Down's pregnancy is akin to eugenics and have the temerity to compare it to Hitler's programme of enforced 'euthanasia' for the mentally feeble. They do themselves no justice with such arguments and comparisons and only serve to raise spurious content which adds nothing to the furtherance of frank and honest debate.

Personally, I am firmly with the parents and their brave decisions. Caring for and raising  a child without mental disability is challenging enough. To embark on the journey knowing the route and the final chilling destination is a parental burden few would knowingly take.     

In the interests of balance- read this and weep:  http://www.voiceforlife.org.nz/eugenics-down-syndrome-from-slippery-slopes-to-play-ground-slides/   

Bert, the oldest living Down syndrome. Died at 83

     

Anyway, I’m off to drink beer and smoke a good cigar with my son….