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11q terminal deletion disorder is a rare genetic disorder. About 1 baby in 100,000 is born with Jacobsen syndrome. The chromosome disorder is twice as common in girls as in boys (Mattina 2009). It is known as a terminal deletion disorder because it is caused by the loss of genes from the end (terminus) of chromosome 11. It is also called Jacobsen syndrome (JS) after the Danish researcher who first identified it in 1973. In this guide, both the names 11q terminal deletion disorder and Jacobsen syndrome are used. The most common features of Jacobsen syndrome in a child are:
– growth delay during pregnancy and later
– delay in development
– some typical facial features
– abnormal number and function of platelets in the blood
– sometimes an unusual number of blood cells
– deficient immune system
– developmental anomalies affecting the heart, kidney, gastrointestinal tract, genitals, central nervous system and skeleton
– problems with vision, hearing, hormones and the immune system