Strategies and clinical outcome of 250 cycles of Preimplantation Genetic Diagnosis for single gene disorders.
BACKGROUND
We report on our experience with preimplantation genetic diagnosis (PGD) for single gene disorders (SGDs), from 1999 to 2004, describing strategies and overall clinical outcome of 250 cycles in 174 couples for 23 different genetic conditions.


METHODS
PGD cycles included 15 for autosomal dominant, 148 for autosomal recessive and 19 for X-linked SGDs. In addition, 68 cycles of PGD for SGDs were performed in combination with HLA matching. The strategy in each case used an initial multiplex PCR, followed by minisequencing to identify the mutation(s) combined with multiplex PCR for closely linked informative markers to increase accuracy. Linkage analysis, using intragenic and/or extragenic polymorphic microsatellite markers, was performed in cases where the disease-causing mutation(s) was unknown or undetectable.


RESULTS
In 250 PGD cycles, a total of 1961 cleavage stage embryos were biopsied. PCR was successful in 3409 out of 3149 (92.4%) biopsied blastomeres and a diagnosis was possible in 1849 (94.3%) embryos. Four hundred and twenty-seven embryos were transferred in 211 cycles, resulting in 71 pregnancies (33.6% per embryo transfer), including 15 biochemical pregnancies, six spontaneous miscarriages, two ectopic pregnancies, which were terminated, and nine pregnancies which are still ongoing. The remaining pregnancies were confirmed to be unaffected and went to term without complications, resulting in the birth of 35 healthy babies.


CONCLUSIONS
Minisequencing for mutation detection combined with multiplex fluorescence PCR for linkage analysis is an efficient, accurate and widely applicable strategy for PGD of SGDs. Our experience provides a further demonstration that PGD is an effective clinical tool and a useful option for many couples with a high risk of transmitting a genetic disease.
Fiorentino
F
F
EmbryoGen-Centre for Preimplantation Genetic Diagnosis, GENOMA-Molecular Genetics Laboratory, Via Po 102, 00198 Rome, Italy. fiorentino@embryogen.it
Biricik
A
A
Nuccitelli
A
A
De Palma
R
R
Kahraman
S
S
Iacobelli
M
M
Trengia
V
V
Caserta
D
D
Bonu
M A
MA
Borini
A
A
Baldi
M
M
D000328:Adult; D001483:Base Sequence; D001755:Blastocyst; D017931:DNA Primers; D005260:Female; D005307:Fertilization in Vitro; D005799:Genes, Dominant; D005808:Genes, Recessive; D030342:Genetic Diseases, Inborn / Q000175:diagnosis* / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D008423:Maternal Age; D009154:Mutation; D010375:Pedigree; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011256:Pregnancy Outcome
D017931:DNA Primers