IDENTIFICATION OF A HUMAN SPECIFIC ALU INSERTION IN THE FACTOR XIIIB GENE

The factor XIIIB gene was examined to determine the nature of a previo usly described 300 bp restriction fragment length polymorphism (RFLP) seen in the human population. Polymerase chain reaction analysis of di fferent regions within the factor XIIIB gene was carried out to define a high resolution map of the region encompassing the polymorphism, fo llowed by DNA sequence analysis. An Alu insertion was found to be the source of this variation. This Alu repeat is a member of the human spe cific-1 (HS-1) subfamily, although one of the five diagnostic nucleoti des is a cattarhine specific (CS) subfamily mutation, suggesting that it may represent an intermediate form in the evolution between these t wo subfamilies. Subsequently, we developed a PCR-based assay to detect the polymorphism, rendering it a more useful marker for genetic linka ge studies and genome mapping. This insertion is also a valuable polym orphism for human population studies, as demonstrated by the large var iations in allele frequencies seen in three population groups.