No. 343-Routine Non-invasive Prenatal Prediction of Fetal RHD Genotype in Canada: The Time is Here.

The optimal management of the D-negative pregnant woman is now based on the non-invasive antenatal prediction of fetal D-blood group by cell-free DNA (cfDNA) in maternal plasma, with targeted prophylaxis for women carrying RHD-positive fetuses. This provides the optimal care for D-negative pregnant women and has been adopted as the standard approach in a growing number of countries around the world. This paper is the result of a consensus meeting of the Canadian National Rh Working Group, an interdisciplinary group formed to review the current status of fetal RHD genotyping based on cfDNA in Canada. The group, in collaboration with the SOGC Genetics committee, reviewed the benefits and challenges of implementing RHD genotyping with targeted prophylaxis in the context of the existing routine antenatal anti D prophylaxis program in Canada. The following summary statements and recommendations are based on this review. SUMMARY STATEMENTS: RECOMMENDATIONS.

No 343-Prédiction du génotype RHD fœtal par test prénatal non invasif de routine au Canada : l'heure est venue.

Actuellement, la meilleure façon de prendre en charge les femmes enceintes Rh négatives consiste à prédire la présence ou l'absence de l'antigène D chez le fœtus au moyen d'un test non invasif analysant l'ADN acellulaire (ADNa) dans le plasma maternel, et à administrer une prophylaxie à celles dont l'enfant est RHD positif. Cette approche, prise pour norme dans un nombre croissant de pays, assure aux femmes enceintes Rh négatives des soins optimaux. La présente directive est le fruit d'une réunion de consensus du groupe de travail national sur le facteur Rh du Canada, un groupe interdisciplinaire formé pour examiner la situation nationale actuelle du génotypage RHD fœtal effectué sur l'ADNa. En collaboration avec le Comité de génétique de la SOGC, le groupe s'est penché sur les avantages et les difficultés associés au génotypage RHD combiné à une prophylaxie ciblée dans le contexte du programme de prophylaxie anténatale anti-D de routine canadien existant. De ce travail ont émergé les déclarations sommaires et recommandations suivantes. DéCLARATIONS SOMMAIRES: RECOMMANDATIONS.

An efficient strategy for large-scale high-throughput transposon-mediated sequencing of cDNA clones.

We describe an efficient high-throughput method for accurate DNA sequencing of entire cDNA clones. Developed as part of our involvement in the Mammalian Gene Collection full-length cDNA sequencing initiative, the method has been used and refined in our laboratory since September 2000. Amenable to large scale projects, we have used the method to generate >7 Mb of accurate sequence from 3695 candidate full-length cDNAs. Sequencing is accomplished through the insertion of Mu transposon into cDNAs, followed by sequencing reactions primed with Mu-specific sequencing primers. Transposon insertion reactions are not performed with individual cDNAs but rather on pools of up to 96 clones. This pooling strategy reduces the number of transposon insertion sequencing libraries that would otherwise be required, reducing the costs and enhancing the efficiency of the transposon library construction procedure. Sequences generated using transposon-specific sequencing primers are assembled to yield the full-length cDNA sequence, with sequence editing and other sequence finishing activities performed as required to resolve sequence ambiguities. Although analysis of the many thousands (22 785) of sequenced Mu transposon insertion events revealed a weak sequence preference for Mu insertion, we observed insertion of the Mu transposon into 1015 of the possible 1024 5mer candidate insertion sites.