14164991-Hirschsprungs-Disease

14164991-Hirschsprungs-Disease - HIRSCHSPRUNG'S DISEASE or...

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HIRSCHSPRUNG'S DISEASE or congenital aganglionic megacolon , involves an enlargement of the colon , caused by bowel obstruction resulting from an aganglionic section of bowel (the normal enteric nerves are absent) that starts at the anus and progresses upwards. The length of bowel that is affected varies but seldom stretches for more than a foot or so. History and Description This disease is named after Harald Hirschsprung , the Danish physician who first described the disease in 1886, describing two infants who had died with swollen bellies. "The autopsies showed identical pictures with a pronounced dilatation and hypertrophy of the colon as the dominant features" (Madsen 17:2). Hirschsprung’s disease is a congenital disorder of the colon in which certain nerve cells, known as ganglion cells, are absent, causing chronic constipation [1] . A barium enema is the mainstay of diagnosis of Hirschsprung’s, though a rectal biopsy showing the lack of ganglion cells is the only certain method of diagnosis. The usual treatment is "pull-through" surgery where the portion of the colon that does have nerve cells is pulled through and sewn over the part that lacks nerve cells (National Digestive Diseases Information Clearinghouse). For a long time, Hirschsprung’s was considered a multi-factorial disorder, where a combination of nature and nurture were considered to be the cause (Madsen 19). However, in August of 1993, two articles by independent groups in Nature Genetics said that Hirschsprung’s disease could be mapped to a stretch of chromosome 10 [2] [3] . This research also suggested that a single gene was responsible for the disorder. However, the researchers were unable to isolate the single gene that they thought caused Hirschsprung’s. Genetic basis In 2002, scientists thought they found the solution. According to this new research, Hirschsprung's is caused by the interaction between two proteins encoded by two variant genes. The RET proto-oncogene on chromosome 10 was identified as one of the genes involved, and it was determined that dominant mutations may occur within this gene leading to a loss of function for the protein it encodes (Passarge 11). The protein with which RET has to interact in order for Hirschsprung’s disease to develop is termed EDNRB , and is encoded by the gene EDNRB located on chromosome 13 . Six other genes were discovered to be associated with Hirschsprung’s. According to the study, these genes are GDNF on chromosome 5 , EDN3 on chromosome 20 , SOX10 on chromosome 22 , ECE1 on chromosome 1 , NRTN on chromosome 19 , and
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14164991-Hirschsprungs-Disease - HIRSCHSPRUNG'S DISEASE or...

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