An Australian health authority has reportedly approved pre-implantation genetic diagnosis (PGD) for autism for the first time.
More accurately, the Reproductive Technology Council (RTC)
of Western Australia (WA) has approved a fertility clinic’s application for PGD of embryonic sex, using male sex as a proxy for increased risk of autism, in a family at high risk of having a child with the condition (presumably because one or more family members are already affected).
The WA Department stressed that all PGD applications were considered on a case-by-case basis and that there was no blanket approval for similar embryo sex selection to reduce the probability of having a child with autism.
Autism or Autism Spectrum Disorder (ASD)
is, as implied by the WA decision, much more common in boys than girls, although recently evidence has emerged that this difference may be less to do with different disease frequencies between the sexes as with a somewhat different presentation in females leading to significant under-diagnosis. It is a complex disease that is not fully understood; multiple genetic variants have been implicated in increased disease risk (see previous news
), but environmental factors are also thought to play a role.
It is therefore not possible to perform pre-implantation genetic diagnosis for autism, although it may become feasible to use forms of pre-implantation genetic risk evaluation, since tests have been developed to identify the presence of selected genetic variants strongly linked with autism risk, to enhance diagnosis (see previous news
). These might prove a more reliable guide to risk than embryonic sex alone, but would not be a reliably predictive (diagnostic) test, and their use would probably be no less controversial. Indeed, a commentary on the WA decision notes the possibility of a link between in vitro
fertilization (IVF) procedures – essential to permit any form of embryo screening or testing – and increased risk of autism in resulting children.
There is probably a significant difference between a national or regional decision to approve any form of selection against embryos for ASD risk, and approval for a specific family in particular (probably very difficult) circumstances. However, the evidence base for this latest development is not very strong, and does raise the question of what other applications based on questionable evidence might logically follow? There are a great many diseases for which genetic factors are widely agreed to affect risk, but testing for which has limited predictive value.