Sex chromosomes and human infertility

Abstract

Infertility is common, affecting one in seven couples. There are a number of well-known factors that impair fertility, e.g. smoking, but in around one quarter of infertility cases, a cause cannot be found. It is likely that in many of these instances, undiagnosed genetic defects are to blame. The human genome, or DNA sequence, is made up of around 20,000 genes, which are distributed over many different chromosomes. One particular pair of chromosomes are referred to as the sex chromosomes, or “X” and “Y” chromosomes. Women have two X chromosomes (XX), while men have one X chromosome and one Y chromosome (XY). The sex chromosomes are unlike other chromosomes, because they play a very special function in human reproduction, i.e. in the creation of eggs and sperm. It is therefore thought that many cases of unexplained human infertility result from genetic defects arising on the sex chromosomes. For scientists, studying sex chromosomes and their role in infertility has proven uniquely challenging, because their DNA sequence is difficult to decode, and they are hard to manipulate experimentally. However, recent technological advances are now removing these hurdles. In this presentation I will explain how sex chromosomes acquired their specialised role in the formation of eggs and sperm, and will outline the latest experimental approaches being developed in laboratories that may one day be used to reverse infertility in humans.

Host: Bob White