X-Linked Spinal Muscular Atrophy (XL-SMA) is a rare congenital disorder characterized by multiple joint contractures. It is associated with hypotonia, areflexia, chest deformities and congenital joint contractures. The purpose of this study is to refine the XL-SMA gene region and discover the XL-SMA gene. In addition to that, the gene product was investigated to delineate the genotype-phenotype correlation. This study will hopefully shine a light to a rare disorder which affects newborns.