Preimplantation Genetic Diagnosis pdf

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Preimplantation Genetic Diagnosis

Mandy G. Katz-Jaffe

Colorado Center for Reproductive Medicine, Englewood, Colorado, U.S.A.

INTRODUCTION

In 1990, preimplantation genetic diagnosis (PGD) was introduced as an

experimental procedure to genetically screen human embryos during an in

vitro fertilization (IVF) cycle (1,2). More than a decade later, PGD has

become an established clinical procedure in assisted reproductive technolo￾gies with over 6500 PGD cycles performed worldwide, resulting in the birth

of well over 1000 healthy babies and a pregnancy rate per transfer of

approximately 24% (3). The safety of PGD is reflected in these comparable

pregnancy rates with conventional IVF, as well as the equivalent incidence

of birth abnormalities in the general population (4). PGD was initially per￾formed for preexisting Mendelian-inherited monogenic disorders including

X-linked disorders involving sex selection (1), cystic fibrosis (5), and Tay￾Sachs disease (6). With the development of interphase single-cell fluorescent

in situ hybridization (FISH) in the early 1990s, PGD has expanded to offer

screening for chromosomal disorders including aneuploidy detection for

clinically significant chromosomes (7,8) and translocations (9,10). PGD

involves the molecular analysis of genetic material derived from oocytes

or embryos during an IVF cycle. Only embryos identified as free of the

indicated genetic disorder or chromosomal error are selected for transfer to

the woman’s uterus. Consequently, an established pregnancy is expected

to be unaffected with respect to the indicated genetic testing.

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