A gene is described as the smallest physical and functional unit of genetic inheritance. Genes contain a protein composition. Every living human being has two copies of each gene from the male parent and the female parent. Normally, most genes are similar to every person. However, they are slightly different from others. These differences in each person's genetic composition largely contribute to the differences in our physical appearances. A gene is described as the smallest physical and functional unit of genetic inheritance. Genes contain a protein composition. Every living human being has two copies of each gene from the male parent and the female parent. Normally, most genes are similar to every person. However, they are slightly different from others. These differences in each person's genetic composition largely contribute to the differences in our physical appearances. There are various defects caused by a disorder in the genetic composition. They are chromosomal abnormalities, single gene defects, multi-factorial problems and teratogenic problems. In this summary, I will discuss defects as a result of chromosomal abnormalities, Down-Syndrome Disorder. I chose this particular topic because it’s interesting. Moreover, I have a personal connection with a relative who has the condition.Trisomy 21 is the most common form of Down syndrome. It is a genetic disorder where an individual has 47 chromosomes in their cell composition instead of 46.Normally; a human being inherits 23 chromosomes from their maternal mother and 23 chromosomes from their paternal father. The mode of inheritance occurs during the pairing of the X and Y chromosome. The chromosome number 21 has an extra chromosome that occurs during or before conception. The extra chromosome number 21 occurs from a nondisjunction in the maternal mother’s egg cell. (Margulies, 2007)The salient features of a child who suffers Down syndrome are their eyes have a slant that is upwards, and their irises have white spots. Their muscles are weak, and mass tone is low. Their nasal bridge is relatively flat. The center of the palms of their hand has creases that are deep and mostly single. Their tongues are somewhat protruding. There large and second toe has a relatively large space compared to what is considered normal. Below is a chromosomal map that shows the difference between the normal pairing of chromosomes and the abnormal pairing that constitutes chromosome number 21.People with Down syndrome are predisposed to respiratory problems, gastrointestinal problems, leukemia, and heart disease, loss of hearing, hypothyroidism, eye disorder and low intellectual IQ. Children with this syndrome have a slow growth than their peers. They have trouble talking and walking. Hence; they have a lower life expectancy. Today, there is no medical cure for Down syndrome condition. However, the possible gene therapies are; speech and physical therapy can help people with the disorder lead normal lives. Moreover, corrective surgery can improve the quality of life.
Margulies, Phillip. Down syndrome. New York: Rosen Pub. Group, 2007. Print.
OMIM has well elaborated genetic topics. It is easy to use. I have learnt the gene-phenotype relationships. The location in the morbid maps, phenotype, phenotype MIM number, inheritance, phenotype mapping key. The map shows the genomic context tap, location, gene locus, gene locus MIM number, phenotype, phenotype MIM number, Inheritance, pheno map key, comments and map symbol.
OMIM has well elaborated
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