Robertsonian translocations--reproductive risks and indications for preimplantation genetic diagnosis.
BACKGROUND
Robertsonian translocations carry reproductive risks that are dependent on the chromosomes involved and the sex of the carrier. We describe five couples that presented for preimplantation genetic diagnosis (PGD).


METHODS
PGD was carried out using cleavage-stage (day 3) embryo biopsy, fluorescence in-situ hybridization (FISH) with locus-specific probes, and day 4 embryo transfer.


RESULTS
Couple A (45,XX,der(14;21)(q10;q10)) had two previous pregnancies, one with translocation trisomy 21. A successful singleton pregnancy followed two cycles of PGD. Couple B (45,XX,der(13;14)(q10;q10)) had four miscarriages, two with translocation trisomy 14. One cycle of PGD resulted in triplets. Couple C (45,XX,der(13;14)(q10;q10)) had four years of infertility; two cycles were unsuccessful. Couple D (45,XY,der(13;14)(q10;q10)) presented with oligozoospermia. A singleton pregnancy followed two cycles of PGD. Couple E (45,XY,der(13;14)(q10;q10)) had a sperm count within the normal range and low levels of aneuploid spermatozoa. PGD was therefore not recommended. No evidence for a high incidence of embryos with chaotic or mosaic chromosome complements was found.


CONCLUSIONS
For fertile couples, careful risk assessment and genetic counselling should precede consideration for PGD. Where translocation couples need assisted conception for subfertility, PGD is a valuable screen for imbalance, even when the risk of viable chromosome abnormality is low.
Scriven
P N
PN
Guy's & St Thomas' Centre for PGD, Cytogenetics Department 5th Floor, Guy's Tower, St Thomas Street, London SE1 9RT, UK4. paul.scriven@gstt.sthames.nhs.uk
Flinter
F A
FA
Braude
P R
PR
Ogilvie
C M
CM
D000328:Adult; D001706:Biopsy; D002882:Chromosomes, Human, Pair 13; D002883:Chromosomes, Human, Pair 14; D002891:Chromosomes, Human, Pair 21; D004314:Down Syndrome / Q000235:genetics; D004624:Embryo Transfer; D004622:Embryo, Mammalian; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D011247:Pregnancy; D019836:Preimplantation Diagnosis; D012307:Risk Factors; D014178:Translocation, Genetic