Screening dilemmas: disability, disease or something in-between?

I was struck by a recent article in the Huffington post, written last month by Rachel Adams, a mother of a child with Down's syndrome. The article was written in response to Jane Brody's piece in the New York Times: a piece that heralded the developments in prenatal screening for Down's syndrome using non-invasive prenatal testing (NIPT). Clinical trials for this technology are commencing in the UK this month (as reported in BioNews 729).

In her article, Brody made the point that NIPT screening allows pregnant women to find out earlier whether their fetus has Down’s syndrome (without the risk of miscarriage associated with previous forms of prenatal testing), and consequently to consider whether or not to continue with that pregnancy.

Brody's article, as Adams points out, was unfortunately timed - October was Down's Syndrome Awareness Month in the USA. The poignant juxtaposition of this push to raise awareness of a condition which Adams describes as a 'livable disability' with the celebration of technologies designed to make its prenatal detection easier (and, presumably, also make the associated process of selective termination swifter and more bearable for women) was jarringly highlighted by both articles.

One of the points that particularly caught my attention in Adams' article was her push to free Down's syndrome from the language rife in Brody's commentary - that of 'disease', of 'risk' and of 'defect'. Instead, Adams convincingly argues, many people living with Down's syndrome can instead be described as the 'healthy' disabled, living successfully and happily with their impairment, free of many of the medical complications possible with their condition. As Adams argues, for this group of individuals, the word 'diseased' seems inappropriate, replete with negativity and notions of suffering that, for many people, are entirely misplaced.

This distinction between the 'healthy disabled' and 'suffering' brings me to the issues around another potential screening programme, and one for which the UK National Screening Committee launched a national consultation in May this year - that is, for spinal muscular atrophy (SMA).

Spinal muscular atrophy is a condition that affects the nervous system and caused generalised muscle weakness. It is recessively inherited, meaning it takes two carrier parents to transmit it. While it lacks the high profile of Down's syndrome, between one in 40 and one in 60 people in the UK are thought to be carriers (1). SMA is unusual in its high variability - indeed, it has been described as the most variable neuromuscular condition presenting in childhood (2).

In its most severe forms, SMA is associated with acute respiratory failure, and, sadly, infantile death, often before 18 months of life (although there are reported cases of children with the severest form of SMA outliving this expectation). However, in its intermediate and milder forms, SMA has the potential to present as the 'livable' disability to which Adams refers.

Unlike 50 years ago, when intermediate SMA was considered a life-limiting condition, developments in medical and lay knowledge about treating scoliosis (spinal curvature), chest clearance to remove obstructions from the lungs during a chest infection and physiotherapy have meant that individuals are often (although not always) able to live full and satisfying lives. They are no longer so encumbered by the  medical complications that can accompany such neuromuscular conditions, the most concerning of which remains susceptibility to chest infections such as pneumonia.

This great variability - the possibility of SMA presenting as a terminal condition or a 'livable' disability - poses huge ethical and social dilemmas in terms of the implementation of a national screening programme. Indeed, the technologies used to screen for SMA cannot as yet accurately predict where on this spectrum of severity a child's SMA will lie, nor the myriad of other factors determine how the child's SMA will actually be experienced.

As Adams' piece brought home for me, the medical language surrounding screening programmes may make it difficult for prospective parents to see the words 'healthy' and 'disabled' as anything but mutually exclusive in the context of the conditions for which screening is currently offered. However, with the national consultation on SMA screening currently in full swing, now may be the time to seriously re-consider the sometimes hazy lines that exist between the terms 'disabled' and 'able', 'healthy' and 'diseased'. Indeed, it is in the context of screening programmes that such terms become critical.