Chromosome 13
Myeloproliferative syndrome 8p11 in this disease, a rearrangement (translocation) of genetic material involving chromosome 13 has been identified. This condition is characterized by a greater number of white blood cells (myeloproliferative disorder) and the development of lymphoma, a cancer related to the blood that causes the formation of tumors in the lymph nodes. Myeloproliferative disorder usually develops into another form of blood cancer called acute myeloid leukemia. Myeloproliferative syndrome 8p11 is the most frequent result of a translocation between chromosome 13 and chromosome 8, written as t (8; 13) (p11; q12). This genetic change fuses part of the ZMYM2 gene on chromosome 13 with part of the FGFR1 gene on chromosome 8. Translocation occurs only in cancer cells.
Feingold Syndrome type 2 is caused by genetic changes that remove small DNA fragments from the long arm (q) of chromosome 13. These mutations are known as 13q31.3 microdeletions. It is characterized by abnormalities in the fingers and toes, particularly shortening of the second and fifth fingers (brachymetophalangia). Other common features include an unusually small head size (microcephaly) and learning disabilities. The 13q31.3 microdeletions involved in this condition eliminate the MIR17HG gene and sometimes part or all other nearby genes. It is believed that the loss of the MIR17HG gene underlies the characteristic features of the disorder, although the loss of other genes may play a role in some cases.
Retinoblastoma, a cancer of the retina that primarily affects children, is caused by abnormalities of a gene called RB1. This gene is found in a region of arm q on chromosome 13 designated 13q14. Although most retinoblastomas are caused by mutations within the RB1 gene, a small percentage of retinoblastomas results from a deletion of the 13q14 region. In addition to retinoblastoma, deletions of the 13q14 region can cause intellectual disability, slow growth and characteristic facial features such as prominent eyebrows, a wide nasal bridge, short nose and ear abnormalities.
Trisomy 13, also known as Patau Syndrome, occurs when each cell in the body has three copies of chromosome 13 instead of the usual two copies; although it can also be presented as a trisomy mosaic 13.
In some cases, trisomy 13 occurs when part of chromosome 13 joins (translocates) to another chromosome during the formation of gametes (ovules and sperm) or very early in embryonic development. The physical signs of translocation trisomy 13 may be different from those typically seen in trisomy 13 because only part of chromosome 13 is present in three copies. Researchers believe that additional copies of some genes on chromosome 13 disrupt the course of normal development, causing the characteristic features of trisomy 13 and the increased risk of medical problems associated with this disorder. It is a chromosomal condition associated with severe intellectual disability and physical abnormalities in many parts of the body. People with trisomy 13 often have heart defects, abnormalities of the brain or spinal cord, very small or underdeveloped eyes (microphthalmia), additional fingers or fingers, an opening in the lip (cleft lip) with or without an opening in the roof of the mouth (cleft palate) and weak muscle tone (hypotonia). Due to the presence of several life-threatening medical problems, many babies with trisomy 13 die within their first days or weeks of life. Only between five and 10 percent of children with this condition live beyond their first year.
Some types of cancer are associated with changes in chromosome 13, these are somatic disorders, which are acquired during the course of life, so they affect only certain cells. Loss of genetic material from chromosome 13 media is common in blood-forming cell cancers (leukemia), immune system cell cancers (lymphomas) and other related cancers.
Other anomalies: Partial monosomy and partial trisomy of chromosome 13 occur when a part of the arm of this chromosome is removed or duplicated, respectively. The effect of lost or extra chromosomal material varies with the size and location of the chromosomal abnormality. Affected people may have developmental delay, intellectual disability, low birth weight, skeletal abnormalities and other physical characteristics.
