Chromosomal instability in aneuploid acute lymphoblastic leukemia associates with disease progression.

Chromosomal instability (CIN) lies at the core of cancer development leading to aneuploidy, chromosomal copy-number heterogeneity (chr-CNH) and ultimately, unfavorable clinical outcomes. Despite its ubiquity in cancer, the presence of CIN in childhood B-cell acute lymphoblastic leukemia (cB-ALL), the most frequent pediatric cancer showing high frequencies of aneuploidy, remains unknown. Here, we elucidate the presence of CIN in aneuploid cB-ALL subtypes using single-cell whole-genome sequencing of primary cB-ALL samples and by generating and functionally characterizing patient-derived xenograft models (cB-ALL-PDX). We report higher rates of CIN across aneuploid than in euploid cB-ALL that strongly correlate with intraclonal chr-CNH and overall survival in mice. This association was further supported by in silico mathematical modeling. Moreover, mass-spectrometry analyses of cB-ALL-PDX revealed a "CIN signature" enriched in mitotic-spindle regulatory pathways, which was confirmed by RNA-sequencing of a large cohort of cB-ALL samples. The link between the presence of CIN in aneuploid cB-ALL and disease progression opens new possibilities for patient stratification and offers a promising new avenue as a therapeutic target in cB-ALL treatment.

ESHRE PGT Consortium good practice recommendations for the detection of monogenic disorders.

The field of preimplantation genetic testing (PGT) is evolving fast and best practice advice is essential for regulation and standardisation of diagnostic testing. The previous ESHRE guidelines on best practice for PGD, published in 2005 and 2011, are considered outdated, and the development of new papers outlining recommendations for good practice in PGT was necessary. The current paper provides recommendations on the technical aspects of PGT for monogenic/single-gene defects (PGT-M) and covers recommendations on basic methods for PGT-M and testing strategies. Furthermore, some specific recommendations are formulated for special cases, including de novo pathogenic variants, consanguineous couples, HLA typing, exclusion testing and disorders caused by pathogenic variants in the mitochondrial DNA. This paper is one of a series of four papers on good practice recommendations on PGT. The other papers cover the organisation of a PGT centre, embryo biopsy and tubing and the technical aspects of PGT for chromosomal structural rearrangements/aneuploidies. Together, these papers should assist scientists interested in PGT in developing the best laboratory and clinical practice possible.

Karyomapping allows preimplantation genetic diagnosis of a de-novo deletion undetectable using conventional PGD technology.

Preimplantation genetic diagnosis (PGD) was carried out for a couple carrying a de-novo deletion in the TSC2 gene, responsible for tuberous sclerosis. Karyomapping, a method employing genome-wide analysis of single nucleotide polymorphisms (SNP), was used as PGD protocol. Analysis of DNA from the affected parent using karyomapping confirmed the region covered by the deletion and revealed more than 30 SNP located within the affected region. These SNP were subsequently used for embryo diagnosis (deletion revealed by hemizygosity and/or reduced probe intensity). Seven blastocyst embryos underwent trophectoderm biopsy followed by vitrification. Biopsied cells were subjected to comprehensive aneuploidy screening using microarray comparative genomic hybridization (aCGH), with karyomapping for the detection of embryos carrying the mutant TSC2 gene carried out in tandem. Two embryo transfers were performed, the second of which resulted in the birth of a child. This study highlights that karyomapping may be applicable to a subset of de-novo mutations undetectable using standard PGD strategies. Additionally, karyomapping results were in complete concordance with aCGH, both methods revealing the same aneuploidies in the embryos tested. It was concluded that karyomapping may represent a valuable advance in cases of PGD for monogenic diseases.

Preimplantation genetic diagnosis for inherited breast cancer: first clinical application and live birth in Spain.

Carriers of a mutation in BRCA1/2 genes confront a high lifetime risk of breast and ovarian cancer and fifty percent probability of passing the mutation to their offspring. Current options for risk management influence childbearing decisions. The indications for preimplantation genetic diagnosis (PGD) have now been expanded to include predisposition for single-gene, late-onset cancer but few cases have been reported to date despite the favorable opinion among professionals and carriers. A 28-year-old BRCA1 mutation carrier (5273G>A in exon 19) with a strong maternal history of breast cancer and 2 years of infertility decided to pursue PGD to have a healthy descendent after an accurate assessment of her reproductive options. The procedure was approved by the national regulation authority and a PGD cycle was initiated. Four out of 6 embryos harbored the mutation. The two unaffected embryos were implanted in the uterus. A singleton pregnancy was achieved and a male baby was delivered at term. Consented umbilical cord blood testing confirmed the accuracy of the technique. Individualized PGD for inherited breast predisposition is feasible in the context of a multidisciplinary team.

Pregnancy outcome after preimplantation genetic diagnosis in an affected couple with X-linked adrenoleukodystrophy.

OBJECTIVE: To achieve a pregnancy free of X-linked adrenoleukodystrophy (X-ALD) by intracytoplasmic sperm injection (ICSI) and preimplantation genetic diagnosis (PGD). DESIGN: Case report. SETTING: Clínica FIV Recoletos, a private IVF center. PATIENT(S): A couple in which the man had X-ALD. INTERVENTION(S): The ICSI protocol and PGD of the obtained embryos. MAIN OUTCOME MEASURE(S): Blastomeres were analyzed by fluorescence in situ hybridization using sex selection techniques. Embryos were transferred and pregnancy was diagnosed by hCG analysis and ultrasonographic examination. RESULT(S): Ten embryos were obtained by ICSI. A biopsy was taken from eight embryos to perform PGD and two male embryos were transferred resulting in a twin pregnancy. CONCLUSION(S): This is the first registered gestation in which PGD has been used to prevent X-ALD transmission.