While there is limited data on CLS in patients after the third decade of life,7 genetic analysis in a 40-year-old maternal uncle of 2 newly diagnosed maleswith CLS revealed mutations of the RPS6KA3 gene.5 More than 125 mutations have been identified with theRPS6KA3 gene, a growth factor-regulated serine-threonineprotein kinase, an X-linked disorder in CLS. The gene discussed is RPS6KA3; the disease is Coffin-Lowry syndrome.