The clinical consequences of mosaicism depend on which chromosome is involved, and when and where an error occurs. Mitotic rescue of a meiotic error or a very early mitotic error will typically lead to general mosaicism while a mitotic error at a specific cell lineage point typically leads to confined mosaicism. The clinical consequences of mosaicism are dependent on numerous aspects, with the consequences being unique for each event.

To date, mutations in two genes, SPATA16 and DPY19L2, have been identified as responsible for a severe teratozoospermia, namely globozoospermia. The two initial descriptions of the DPY19L2 deletion lead to a very different rate of occurrence of this mutation among globospermic patients. In order to better estimate the contribution of DPY19L2 in globozoospermia, we screened a larger cohort including 64 globozoospermic patients. Twenty of the new patients were homozygous for the DPY19L2 deletion, and 7 were compound heterozygous for both this deletion and a point mutation. We also identified four additional mutated patients. The final mutation load in our cohort is 66.7% (36 out of 54). Out of 36 mutated patients, 69.4% are homozygous deleted, 19.4% heterozygous composite and 11.1% showed a homozygous point mutation. The mechanism underlying the deletion is a non-allelic homologous recombination (NAHR) between the flanking low-copy repeats. Here, we characterized a total of nine breakpoints for the DPY19L2 NAHR-driven deletion that clustered in two recombination hotspots, both containing direct repeat elements (AluSq2 in hotspot 1, THE1B in hotspot 2). Globozoospermia can be considered as a new genomic disorder. This study confirms that DPY19L2 is the major gene responsible for globozoospermia and enlarges the spectrum of possible mutations in the gene. This is a major finding and should contribute to the development of an efficient molecular diagnosis strategy for globozoospermia.

The value of preimplantation genetic testing for aneuploidy (PGT-A) as a screening test for in vitro fertilization (IVF) patients has yet to be determined. Several studies demonstrate higher birth rates after aneuploidy testing and elective single-embryo transfer (eSET), suggesting the potential for this testing to decrease the risk of multiple gestations, though these studies have important limitations.

Based on American Society for Reproductive Medicine (ASRM) and Society for Assisted Reproductive Technology data available through 2014, ASRM's guidelines for the limits on the number of embryos to be transferred in in vitro fertilization (IVF) cycles have been further refined in continuing efforts to promote singleton gestation and reduce the number of multiple pregnancies. This version replaces the document titled Criteria for number of embryos to transfer: a committee opinion that was published most recently in August of 2013 (Fertil Steril 2013;99:44-6).