( Quickly identify closely...)Map and Link Human Genetic Disorders with SSLP Analysis

Quickly identify closely related alleles with the CastAway system

Michelle L. Mack Douglas J. Wilkin
Medical Genetics Branch, National Human Genome Research Institute National Institutes of Health, Bethesda, MD

Stratagenes CastAway system is ideal for analyzing SSLPs (simple sequence-length polymorphisms), or microsatellites. Different alleles that contain these polymorphisms can vary by just a few bases. With the CastAway denaturing polyacrylamide gels,* it is now easy to separate the PCR products containing these polymorphisms. The system consistently produces high-quality band resolution.

The field of human genetics has greatly accelerated due in part to recent advances in the development of tools to map human genetic disorders. New methods generated to discover the chromosomal location of disease genes, and identify the gene after the map location is known, have aided the rapid identification of new disease genes. Recognition of the heterogeneity of genetic diseases, the allelic nature of certain disorders, and mutational heterogeneity in the cause of genetic conditions may ultimately lead to understanding the relationship between phenotype and gene.

Simple Sequence-Length Polymorphism Analysis

To identify disease loci, small fragments of genomic DNA must be analyzed. These markers, SSLPs or microsatellites, are derived from unique stretches of DNA that contain very short, simple-sequence repeats.¹ Each microsatellite marker is made up of a variable number of di-, tri-, or tetranucleotide repeats at a particular location.¹ Often these markers are (CA)n repeat polymorphisms.¹ These polymorphisms can easily be genotyped by PCR with primers that anneal to single-copy DNA, which flanks the repetitive element.

Genotyping, using microsatellite markers, at
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