Carrier Detection of Wiscott-Aldrich Syndrome by X-Inactivation Analysis
Houston, Rochelle M.
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The Wiskott Aldrich Syndrome is a X-linked recessive disorder characterized by thrombocytopenia, eczema, and immunodeficiency. In an attempt to develop a procedure for detecting female heterozygotes using a nonradioactive probe, DNA sequences containing the gene for hypoxanthane phosphoribosyl transferase were modified by nick translation to incorporate biotinylated uridine monophosphate. The resulting biotinylated DNA probes were then hybridyzed to DNA that had been obtained from females and digested with two different restriction endonucleases. The first restriction endonuclease was designed to distinguish between the two X-chromosomes; the second enzyme was designed to distinguish between the active and the inactive X-chromosome. While the biotinylated DNA had adequate color development following treatment with a streptavidin-alkaline phosphatase conjugate and a chromogenic substrate, the probes bound to genomic DNA nonspecifically and failed to identify specific DNA fragments. These results indicate that further experiments are needed to develop a satisfactory nonradioactive test system.