Preimplantation genetic diagnosis for the Kell genotype.

OBJECTIVE: To use preimplantation genetic diagnosis (PGD) to achieve a Kell 1 (K1) allele-free pregnancy in couples at risk for producing a child with hemolytic disease of the newborn (HDN) caused by maternofetal incompatibility in sensitized mothers. DESIGN: DNA analysis of biopsied blastomeres from cleavage-stage embryos in IVF-ET with the goal of identifying and transferring back to patients the K1 allele-free embryos. SETTING: IVF program at the Reproductive Genetics Institute, Chicago, Illinois, and IVF Michigan, Rochester Hills, Michigan. PATIENT(S): Two at-risk couples with a history of neonatal death caused by HDN due to K1/K2 genotype in a male partner. INTERVENTION(S): Biopsy of single blastomeres and testing for paternal K1 allele in each embryo after standard IVF. MAIN OUTCOME MEASURE(S): DNA analysis of blastomeres indicating whether corresponding embryos were K1 allele-free for the purpose of transferring only embryos without the K1 allele. RESULT(S): Of 36 embryos tested in five cycles from two couples, 18 were predicted to be K1 allele-free. Of these, 9 were transferred, resulting in a K1 allele-free twin pregnancy and the birth of two healthy children. CONCLUSION(S): PGD of the K1 genotype resulted in the birth of healthy twins confirmed to be free of the K1 allele. PGD in couples with a heterozygous K1/K2 male partner provides an option for avoiding HDN in sensitized mothers.

Preimplantation genetic diagnosis for cancer predisposition.

Preimplantation genetic diagnosis (PGD) has recently been offered for couples with an inherited predisposition for late onset disorders. This paper presents the results of PGD for a group of couples at risk for producing children with cancer predisposition. Using a standard IVF procedure, oocytes or embryos were tested for different mutations predisposing to cancer, preselecting and transferring only mutation-free embryos back to the patients. The procedure was performed for patients with predisposition to familial adenomatous polyposis coli (FAP), Von Hippel-Lindau syndrome (VHL), retinoblastoma, Li-Fraumeni syndrome, determined by p53 tumour suppressor gene mutations, neurofibromatosis types I and II and familial posterior fossa brain tumour (hSNF5). Overall, 20 PGD cycles were performed for 10 couples, resulting in preselection and transfer of 40 mutation-free embryos, which resulted in five unaffected clinical pregnancies and four healthy children born by the present time. Despite the controversy of PGD use for late onset disorders, the data demonstrate the usefulness of this approach as the only acceptable option for at-risk couples to avoid the birth of children with an inherited predisposition to cancer, and to have a healthy child.

Preimplantation diagnosis for early-onset Alzheimer disease caused by V717L mutation.

CONTEXT: Indications for preimplantation genetic diagnosis (PGD) have recently been expanded to include disorders with genetic predisposition to allow only embryos free of predisposing genes to be preselected for transfer back to patients, with no potential for pregnancy termination. OBJECTIVE: To perform PGD for early-onset Alzheimer disease (AD), determined by nearly completely penetrant autosomal dominant mutation in the amyloid precursor protein (APP) gene. DESIGN: Analysis undertaken in 1999-2000 of DNA for the V717L mutation (valine to leucine substitution at codon 717) in the APP gene in the first and second polar bodies, obtained by sequential sampling of oocytes following in vitro fertilization, to preselect and transfer back to the patient only the embryos that resulted from mutation-free oocytes. SETTING: An in vitro fertilization center in Chicago, Ill. PATIENTS: A 30-year-old AD-asymptomatic woman with a V717L mutation that was identified by predictive testing of a family with a history of early-onset AD. MAIN OUTCOME MEASURES: Results of mutation analysis; pregnancy outcome. RESULTS: Four of 15 embryos tested for maternal mutation in 2 PGD cycles, originating from V717L mutation--free oocytes, were preselected for embryo transfer, yielding a clinical pregnancy and birth of a healthy child free of predisposing gene mutation according to chorionic villus sampling and testing of the neonate's blood. CONCLUSION: This is the first known PGD procedure for inherited early-onset AD resulting in a clinical pregnancy and birth of a child free of inherited predisposition to early-onset AD.

Preimplantation diagnosis for neurofibromatosis.

Preimplantation genetic diagnosis (PGD) has recently been performed for inherited cancer predisposition determined by p53 tumour suppressor gene mutations, suggesting the usefulness of PGD for late onset disorders with genetic predisposition, including those caused by the germline mutations of other tumour suppressor genes. Here PGD was performed for two couples, one at risk for producing a child with maternally derived neurofibromatosis type I (NF1), and the other with paternally derived neurofibromatosis type II (NF2). The procedure involved a standard IVF protocol, combined with testing of oocytes or embryos prior to their transfer back to the patients. Maternal mutation Trp-->Ter (TGG-->TGA) in exon 29 of the NF1 gene was tested by sequential PCR analysis of the first and second polar bodies, and paternal L141P mutation in exon 4 of the NF2 gene by embryo biopsy at the cleavage stage. In both cases, multiplex nested PCR was applied, involving NF1 and NF2 mutation analysis simultaneously with the 3 and 2 linked markers, respectively. Of 57 oocytes tested in four PGD cycles for NF1 mutation, 26 mutation-free oocytes were detected, from which eight were preselected for transfer, two in each cycle. These produced two clinical pregnancies, one confirmed to be mutation free by chorionic villus sampling but ending in a stillbirth, and the other still ongoing. Of 18 embryos analysed in a cycle performed for NF2 mutation, eight mutation-free embryos were detected, three of which were transferred back to the patient, resulting in a singleton pregnancy and the birth of a mutation-free child. This suggests that PGD is a useful approach for avoiding the birth of children with inherited cancer predisposition, determined by NF1 and NF2 gene mutations.

Preimplantation diagnosis for p53 tumour suppressor gene mutations.

Preimplantation genetic diagnosis (PGD) was introduced for high-risk couples to avoid establishing affected pregnancies potentially requiring termination following prenatal diagnosis. This opens the possibility for PGD for late onset disorders with genetic predisposition, including inherited cancer predisposition, because only embryos free from the predisposing gene may be transferred back to the patient, with no potential risk for pregnancy termination. PGD was performed for two couples, one with maternally and one with paternally derived p53 tumour-suppressor mutations, 902insC in exon 8 and G524A in exon 5, respectively. This involved a standard IVF protocol, allowing oocytes or embryos to be tested prior to their transfer back to uterus. Maternal mutation was tested by sequential PCR analysis of the first and second polar bodies, removed following maturation and fertilization of oocytes, while paternal mutation analysis required embryo biopsy at the cleavage stage. To avoid misdiagnosis due to allele drop out, multiplex nested PCR was applied, involving p53 mutation analysis simultaneously with the linked short tandem repeats in intron 1. Of 10 oocytes tested in two PGD cycles for 902insC mutation, four unaffected oocytes were pre-selected for transfer yielding no clinical pregnancy. Of 18 embryos analysed in two cycles for G524A mutation, seven mutation-free embryos were detected, two of which were transferred in each cycle, resulting in a singleton pregnancy and birth of a mutation-free child. This is the first PGD for inherited cancer predisposition determined by p53 tumour suppressor mutations, resulting in a clinical pregnancy and birth of a child free from inherited cancer predisposition.