Genetic diagnosis by DNA analysis: progress through amplification

The polymerase chain reaction, a review of the practical limitations for human immunodeficiency virus diagnosis

The polymerase chain reaction (PCR) is a powerful method for the in vitro amplification of specific nucleic acid sequences. As very small amounts of a virus genome can be detected it has obvious diagnostic applications. The background to the reaction and its use for human immunodeficiency virus (HIV) detection are described. The problems likely to be encountered in using PCR as a diagnostic assay (false positives and negatives) and the practical measures which can be taken to overcome them are discussed.

DNA restriction fragment length polymorphisms in differential diagnosis of genetic disease: application in neuromuscular diseases

Three families, in which several male individuals suffer from a hereditary neuromuscular disease, were examined by analysis of naturally occurring restriction fragment length polymorphisms (RFLPs) and by screening for deletions. Originally, differential diagnosis included spinal muscular atrophy (two families) and limb girdle syndrome (one family) or Becker muscular dystrophy. Since deletions were not detectable, an X-chromosomal segment, carrying DNA markers for the dystrophin gene and its flanking regions was reconstructed; this demonstrated Becker muscular dystrophy is the most probable primary cause of illness in these families. Furthermore, the possible carriership of female members of these families could be determined accurately.