RESUMEN
Brachydactyly type B (BDB) is an autosomal dominant disease caused by mutations in the ROR2 gene. Truncating mutations lead to the severe form of the disease, which is characterized by terminal deficiency of fingers and toes. Preimplantation genetic diagnosis (PGD) was carried out in a family suffering from severe BDB. The family was screened for mutations in exons 8 and 9 and found to harbour a known nonsense mutation (c.2265C-->A) in exon 9 of the ROR2 gene, which resulted in a premature stop-codon at residue 755. Three out of 10 linked markers tested were informative for this family and single cell work-up showed amplification efficiency in over 98% of the cells. Allele drop-out (ADO) was found in 0, 4.08 and 6.1% for D9S1803, D9S1842 and D9S280 respectively. The family underwent PGD using multiple displacement amplification, fluorescent polymerase chain reaction (informative short tandem repeat) and sequencing of exon 9. Two cells were taken from the three embryos generated in the PGD cycle and the diagnosis of both cells separately showed one normal embryo free of BDB abnormal allele. This embryo was transferred back to the mother and resulted in a singleton pregnancy. Postnatal DNA testing of the newborn confirmed the PGD result.
Asunto(s)
Deformidades Congénitas de las Extremidades/diagnóstico , Diagnóstico Preimplantación , Codón sin Sentido/genética , Análisis Mutacional de ADN , Técnicas de Cultivo de Embriones , Femenino , Fertilización In Vitro , Humanos , Recién Nacido , Deformidades Congénitas de las Extremidades/genética , Masculino , Linaje , Polimorfismo de Nucleótido Simple , Embarazo , Diagnóstico Preimplantación/métodos , Receptores Huérfanos Similares al Receptor Tirosina Quinasa , Receptores de Superficie Celular/genética , Resultado del TratamientoRESUMEN
Recurrent IVF failure, implantation failure and early embryo demise can be attributed to the high frequency of chromosomal aneuploidy observed in human embryos. Preimplantation genetic screening (PGS) using multiple displacement amplifications (MDA) and array comparative genomic hybridization (aCGH) was successfully performed on eight patients with a minimum of seven recurrent IVF failures with the aim of detecting aneuploidy and ameliorating pregnancy rate. A total of 41 embryos with eight or more cells were biopsied by taking two blastomeres from each embryo. The DNA from these blastomeres were amplified and analysed by aCGH technology. The aCGH results showed a complex panel of chromosomal abnormalities in 60% of the diagnosed embryos. Some abnormalities could not be detected by the seven-probe panel (13, 16, 18, 21, 22, X and Y) used in fluorescence in-situ hybridization. Six out of eight patients had embryos for transfer with five out of those six showing positive pregnancy tests. As far as is known, this report is the first to show a pregnancy after PGS using the aCGH technology. The pregnancy rate obtained here is encouraging and will open the door for enrollment of more patients.