Short stature is a hallmark of TS, with an estimated mean loss of 20 cm associated with X chromosome aneuploidy.[4] Studies of this condition have increased our understanding of the role of sex chromosomes in growth regulation and led to the discovery of the SHOX gene.[5] Short stature in TS is characterized by mild intrauterine growth retardation, slow growth during infancy, delayed onset of the childhood component of growth, and growth failure during childhood and adolescence without a pubertal growth spurt. The gene discussed is SHOX; the disease is Timothy syndrome.