Key content
 Preimplantation genetic diagnosis (PGD) was developed for couples at risk of transmitting a genetic disorder to their children.
 Before PGD, options available to these couples were remaining childless, prenatal diagnosis, gamete donation or adoption.
 Couples requesting PGD have in vitro fertilisation (IVF) to produce embryos for biopsy, even if they are fertile.
Learning objectives
 To understand indications for PGD.
 To learn about the genetic work up required prior to undergoing IVF.
 To learn about IVF, embryogenesis, the biopsy process and when to transfer disease-free/carrier embryo(s).
Ethical issues
 PGD for ‘saviour sibling’: should couples be offered human leucocyte antigen (HLA) matched treatment for a child who is in remission or who may develop the late onset condition?
 PGD for sex selection: should we offer sex selection for
‘family balancing’?
Keywords: IVF / preimplantation genetic diagnosis

Introduction

Indications for PGD

Baseline investigations for a couple requiring preimplantation
genetic diagnosis.
Investigation Woman Man
Hepatitis B & C Yes Yes
HIV Yes Yes
Rubella Yes N/A
Ovarian reserve test
(FSH/E2/AMH/AFC/BMI)
Yes N/A
2D scan* Yes N/A
Semen fluid analysis N/A Yes

Conclusion
PGD has revolutionised PND. For many couples, it has
mitigated the psychological burden of the risk of transmission
of an inherited disorder to their children and avoids the mental
and physical trauma of termination of an affected pregnancy.
Despite women going through the IVF process and its
associated risks, they feel the benefits of PGD outweigh the
risks, albeit without a guarantee of a live birth. Recent advances
in PGD methodology, such as karyomapping, have meant that
for couples who have a known affected relative, child or
pregnancy, the work up time to be able to make a genetic
diagnosis has dramatically reduced. Furthermore, the added
advantage of aneuploidy screening will minimise the risk of
implantation failure and miscarriage. However, powered
multicentre randomised controlled trials are required in the
future to assess the primary endpoint as to whether live birth is
significantly superior with the use of new technology compared
with conventional methods.