[Contribution of genotyping for fetal sex determination in maternal serum for preimplantation genetic diagnosis of X-linked diseases].
OBJECTIVE
Couples with a risk of transmitting X-linked diseases included in a preimplantation genetic diagnosis (PGD) center need early and rapid fetal sex determination during pregnancy in two situations. The first situation corresponds to control of embryo sexing after PGD, the second one being that of couples in PGD program having a spontaneous pregnancy. Determination of fetal sex can be achieved by karyotyping using invasive procedures such as chorionic villus sampling (CVS), amniocentesis or cordocentesis and by non-invasive procedures such as ultrasound (US) examination. CVS is the earliest invasive procedure for fetal sex determination and molecular analysis of X-linked genetic disorders during the first trimester but it is associated with a risk of fetal loss. US allows reliable fetal sex determination only during the second trimester. Recently, reliable non-invasive fetal sex determination was realized by using SRY gene amplification in maternal serum.


METHODS
We report the prospective use of fetal sex determination in maternal serum in our PGD center. Management of pregnancies was performed using this non-invasive procedure in four cases of embryo sexing control and nine cases of spontaneous pregnancies in couples included in PGD program for X-linked diseases.


RESULTS
Fetal sex results using SRY gene amplification on maternal serum were in complete concordance with fetal sex observed by cytogenetic analysis or US examination, as well as at birth.


CONCLUSIONS
This new strategy allowed rapid sex determination during the first trimester and permitted to avoid performing invasive procedures in nine pregnancies.
Tachdjian
G
G
Service de biologie et génétique de la reproduction, hôpital Antoine-Béclère, 157, rue de la Porte-de-Trivaux, 92140, Clamart, France. gerard.tachdjian@abc.ap-hop-paris.fr
Costa
J M
JM
Frydman
N
N
Ray
P
P
Le Dû
A
A
Kerbrat
V
V
Ernault
P
P
Frydman
R
R
D000328:Adult; D004247:DNA / Q000097:blood*; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis / Q000235:genetics; D024282:Genes, sry / Q000235:genetics; D040181:Genetic Diseases, X-Linked / Q000175:diagnosis* / Q000235:genetics; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D019836:Preimplantation Diagnosis; D011446:Prospective Studies; D012732:Sex Determination Analysis
D004247:DNA