Recent advances in newborn screening and molecular genetics are transforming our understanding of the genetic basis of diseases that affect individuals of all ages. It is essential for clinicians to understand the methods and goals of newborn screening (NBS), the principles of genetics, and the methods of molecular analysis including Southern blots, PCR amplification, DNA sequence analysis, Reverse Transcriptase PCR, Multiplex Ligation- dependent Probe Amplification analysis, Fluorescence in Situ Hybridization, Comparative Genomic Hybridization, as well as Fetal Ultrasonography. This understanding and applications of these tools can lead to genetic diagnoses by identifying risks from newborn screening results or family histories, selecting appropriate tests and understanding the implications of test results to the patient and their families. To facilitate this understanding we will review newborn screening, basic genetics, inheritance and examples of established and new methods used in genetic testing. It is our hope that this material will facilitate clinician's abilities to consider and detect genetic disorders so that earlier interventions and optimal outcomes can occur.