Chromosome 11
Beckwith-Wiedemann syndrome is the result of abnormal regulation of genes in part of the short (p) arm of chromosome 11. The genes are located very close together in a designated region 11p15.5. The disorders are caused by the genetic imprint, that is to say by the way in which each of the chromosomes that make up the pair 11 inherited by the father and the mother is expressed or not. About 20 percent of cases of Beckwith-Wiedemann syndrome are caused by a genetic change known as paternal uniparental disomy (UPD). The paternal UPD causes people to have two active copies of inherited genes paternally instead of an active copy of the father and an inactive copy of the mother. People with paternal UPD also lack genes that are active only in the maternal copy of the chromosome. In Beckwith-Wiedemann syndrome, paternal UPD usually occurs early in embryonic development and affects only some of the body's cells (mosaicism).
About 1 percent of all people with Beckwith-Wiedemann syndrome have a chromosomal abnormality, such as a rearrangement (translocation) that involves 11p15.5 or abnormal copying (duplication) or removal of genetic material in this region.
Emanuel syndrome is caused by the presence of additional genetic material from chromosome 11 and chromosome 22 in each cell. In addition to the usual 46 chromosomes, people with Emanuel syndrome have an extra (supernumerary) chromosome consisting of a piece of chromosome 22 attached to a piece of chromosome 11. The additional chromosome is known as a derived chromosome 22.
People with Emanuel syndrome generally inherit the der chromosome (22) from an unaffected parent. The father carries a chromosomal reorganization between chromosomes 11 and 22 called a balanced translocation. No genetic material is gained or lost in a balanced translocation, so these chromosomal changes generally do not cause any health problems. As the translocation is passed to the next generation, it can become unbalanced. As a result of the additional chromosome, people with Emanuel syndrome have three copies of some genes in each cell instead of the usual two copies. Excess genetic material disrupts the normal course of development, leading to intellectual disability and birth defects.
Ewing's sarcoma is caused by a translocation that involves chromosome 11. These tumors develop in bones or soft tissues, such as nerves and cartilage. This translocation, t (11; 22), fuses part of the EWSR1 gene of chromosome 22 with part of the FLI1 gene of chromosome 11, creating the fusion gene EWSR1 / FLI1. This mutation is acquired during the life of a person and is present only in tumor cells. This type of genetic change, called somatic mutation, is not inherited.
Jacobsen syndrome, which is also known as 11q terminal deletion disorder, is caused by a deletion of genetic material at the (terminal) end of the long arm (q) of chromosome 11. The size of the deletion varies among affected people, with most affected people missing from approximately 5 to 16 million DNA building blocks (also written as 5 Mb to 16 Mb). In almost all affected people, suppression includes the tip of chromosome 11. Larger deletions tend to cause more severe signs and symptoms than smaller suppressions.
Signs and symptoms of Jacobsen syndrome vary considerably, may present developmental delay, language and motor skills. Most also have cognitive impairment, learning difficulties, behavioral problems, including compulsive behavior (such as shredding paper), a short attention span and easy distraction. Many people with Jacobsen syndrome have been diagnosed with attention deficit / hyperactivity disorder (ADHD). Jacobsen syndrome is also associated with a higher probability of autism spectrum disorders. 90% of people with this disorder may also have bleeding problems known as Paris-Trousseau syndrome.
About 35 percent of people with Neuroblastoma have a removal of genetic material on the long arm (q) of chromosome 11 in a position designated as 11q23. Neuroblastoma is a type of cancerous tumor composed of immature nerve cells (neuroblasts). The 11q23 deletion can occur in the body's cells after conception, which is called somatic mutation, or it can be inherited from a parent. This elimination is associated with a more severe form of neuroblastoma. Researchers believe that the deleted region may contain a gene that prevents cells from growing and dividing too quickly or uncontrollably, called a tumor suppressor gene.
Russell-Silver Syndrome may be the result of changes in genes in the 11p15.5 region. Specifically, Russell-Silver syndrome has been associated with changes in genomic imprinting that affect the regulation of the H19 and IGF2 genes on chromosome 11. The changes are different from those observed in Beckwith-Wiedemann syndrome and have the effect opposite about growth. Although both disorders can be caused by abnormal regulation of these genes, the changes that cause Russell-Silver syndrome lead to slow growth and short stature rather than overgrowth.
WAGR syndrome is caused by a removal of genetic material in the short arm (p) of chromosome 11 in a position described as 11p13. WAGR syndrome is a disorder that affects many body systems and is named for its main characteristics: a childhood kidney cancer known as Wilms tumor, an eye problem called aniridia, genitourinary abnormalities and intellectual disability (previously known as delay mental). The signs and symptoms of WAGR syndrome are related to the loss of multiple genes from this part of the chromosome. The size of the elimination varies among the people affected. Researchers have identified genes in the short arm of chromosome 11 that are associated with particular characteristics of WAGR syndrome. A loss of the PAX6 gene disrupts normal eye development, causing aniridia and other eye problems, and can also affect brain development. The elimination of the WT1 gene is responsible for genitourinary abnormalities and the increased risk of Wilms tumor in affected people.
Several types of cancer are a consequence of alterations in chromosome 11. These mutations appear during a person's life and are present only in certain cells. These may be translocations of genetic material between chromosome 11 and other chromosomes, which have been associated with cancers of blood-forming cells (leukemia) and cancers of immune system cells (lymphomas).
Other alterations that may occur on chromosome 11 may include: translocations with genes from other chromosomes, missing or surplus genetic material; mutations that lead to multiple disorders.
