Vite degne di essere vissute e diagnosi di preimpianto

Su BioNews («PGD and the Human Tissue and Embryos (Draft) Bill», 11 giugno 2007) John Gillott avanza un argomento decisamente degno di nota a proposito della diagnosi genetica di preimpianto (preimplantation genetic diagnosis, PGD, in inglese). Rispondendo a un critico che paventa la possibilità che le vite dei disabili possano più facilmente essere ritenute non degne di essere vissute con la progressiva diffusione e l’ampliamento della PGD, scrive:

In reality prospective parents and society do not see selection as being about avoiding conditions ‘inconsistent with a worthwhile life’ – in many cases they see it as a choice between two worthwhile lives, one of which would also be free from a known genetic risk or condition. I would be very surprised if the father-to-be in the recent case, who has CFEM [congenital fibrosis of the extraocular muscles, una malattia che limita gravemente la visione] himself, saw his life as not being worthwhile.

Molto ragionevole anche questo punto successivo:

The threat of ‘eugenics’ is often wheeled out, or the motives of prospective parents seeking PGD are sometimes labelled ‘perfectionist’ (and this is considered grounds on which to restrict choice). In reality, what parents want to achieve through PGD is a healthy child; not a perfect child but a child free from a known risk. Why should there be any restriction on the genetic risk factors that can be excluded? In practice, taking account of all that is involved, there are many disincentives to using PGD, meaning that parents themselves are inclined to try to use it only for what they and many others would agree are serious conditions. But looking to the future, if a woman were already undergoing IVF and perhaps also PGD and was to make a request for a broader genetic screen, then why not? Evidence suggests that embryo biopsy does no harm to the future child, and IVF involves the selection of embryos as a matter of course. There is no ‘slippery slope’, just the hope of a slippery, slimy and healthy newborn baby.