The use of subtelomeric probes to study mental retardation.

In this chapter, we focus on the genetic basis of mental retardation (MR), specifically the use of subtelomeric probes to provide new diagnoses in idiopathic MR. We discuss both the background to the clinical demand for diagnoses and the technological advances that culminated in the development of subtelomeric testing strategies. We explain the theory behind these strategies and briefly outline the protocols involved, giving the advantages, limitations, and pitfalls of the analyses. Finally, we give an overview of the MR subtelomeric studies to date and how subtelomeric testing has become a widely used tool in clinical diagnostic laboratories, particularly in the diagnosis of unexplained MR, but also in other fields of clinical medicine. The conclusion addresses the overall impact that subtelomeric testing has had on the diagnosis of MR, the implications for patients and their families, and future research avenues for exploring the genetic causes of MR and improving our overall understanding of neurocognitive development.