The search for SNPs,CNVs, and epigenetic variants associated with the complex disease of male infertility

Understanding the genetic basis of idiopathic male infertility has long been the focus of many researchers. Numerous recent studies have attempted to identify relevant single nucleotide polymorphisms (SNPs) through medical re-sequencing studies in which candidate genes are sequenced in large numbers of cases and controls in the search for risk or causative polymorphisms. Two major characteristics have limited the utility of the re-sequencing studies. First, reported SNPs have only accounted for a small percentage of idiopathic male infertility. Second, SNPs reported to have an association with male infertility based on gene re-sequencing studies often fail validation in follow-up studies. Recent advances in the tools available for genetic studies have enabled interrogation of the entire genome in search of common, and more recently, rare variants. In this review, we discuss the progress of studies on genetic and epigenetic variants of male infertility as well as future directions that we predict will be the most productive in identifying the genetic basis for male factor infertility based on our current state of knowledge in this field as well as lessons learned about the genetic basis for complex diseases from other disease models.