image: Splicing of human gene transcripts by two different “spliceosomes”. There are two types of introns found in human genes. About 99 percent of genes contain only introns of the “major” class (top) while about 1 percent of genes have one or more introns of the “minor” class (bottom). Both types of introns must be spliced correctly for all genes to be properly expressed. Splicing is carried out by large, complex molecular machines called “spliceosomes”. Patients who have two defective chromosomal copies of a critical component of the minor spliceosome cannot efficiently splice out their minor class introns (bottom, right). This leads, in ways we do not fully understand, to the developmental defects seen in MOPD I. This image relates to an article that appeared in the April 8, 2011, issue of Science, published by AAAS. The study, by H. He of Ohio State University in Columbus, Ohio, and colleagues was titled, "Mutations in U4atac snRNA, a Component of the Minor Spliceosome, in the Developmental Disorder MOPD I." view more
Credit: Image © <i>Science/</i>AAAS