The actinins are actin bundling proteins important in cytoskeletal organization. There are 4 known isoforms in the human, some of which are important in muscle and others in non-muscle cells. We have cloned 3 of these and identified naturally occurring alleles in the population that we believe have functional effects in a variety of cell types. We have also found interesting elements in the genomic region flanking one of these genes that has prompted us to study its coordinate regulation with a gene important to blood cell development. We are presently investigating both tissue distribution and regulation of the different actinin, prior to beginning a clinical screening to study the affect of the alleles we have identified.