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.

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Two fragile sites, FRA16B and FRA16C, are located in the chromosome band 16q22.1. Neither of them is associated with any specific clinical condition. We report the development and outcome of a clinically applied PGD cycle in a couple who had difficulty in achieving pregnancy. The woman was a carrier of a balanced reciprocal translocation, t(11;22)(q23;q11.2), and the man presented high expression of the fragile site 16q22.1 (FRA16B/C) in peripheral blood lymphocytes. Gains and losses of chromosome 16 fragments were detected in sperm and embryos. To our knowledge, this is the first documented case suggesting a link between FRA16B/C and chromosome 16 abnormalities in embryos and sperm from a carrier.

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