We, the investigators at the University of Texas Health Science Center at San Antonio, want to learn if height and IQ (intelligence quotient) scores are improved by growth hormone (GH) treatment in children with chromosome 18 deletions and abnormal growth. Data from a previous study showed that growth hormone improved height in all children with 18q- and growth hormone deficiency. In addition, most of the study participants on growth hormone treatment showed an increase in IQ scores.