Wednesday, December 28, 2011

Chromosome I

I have decided that I am going to debut a new "series" in which I go over each of the human chromosomes and information pertaining to it. Of course, I'm going to start off with Chromosome #1.

What is Chromosome I?
Chromosome 1 is the largest human chromosome, spanning about 247 million DNA building blocks (base pairs) and representing approximately 8 percent of the total DNA in cells. Chromosome 1 likely contains more than 3,000 genes, which perform a variety of different roles in the body.

How Do Changes in Chromosome I Affect Health?
The following chromosomal conditions are associated with changes in chromosome I (Not a complete list):

  • 1p36 deletion syndrome 
    • 1p36 deletion syndrome is caused by a deletion of genetic material from a specific region in the short (p) arm of chromosome 1. The signs and symptoms of this disorder, which include intellectual disability, distinctive facial features, and structural abnormalities in several body systems, are probably related to the loss of multiple genes in this region. The size of the deletion varies among affected individuals 
  • Neuroblastoma 
    • Neuroblastoma is a type of cancerous tumor composed of immature nerve cells (neuroblasts). These deletions are somatic mutations, which means they occur during a person's lifetime and are present only in the cells that become cancerous. About 25 percent of people with neuroblastoma have a deletion of 1p36.1-1p36.3, which is associated with a more severe form of neuroblastoma. Researchers believe the deleted region could contain a gene that keeps cells from growing and dividing too quickly or in an uncontrolled way, called a tumor suppressor gene. When tumor suppressor genes are deleted, cancer can occur. Researchers have identified several possible tumor suppressor genes in the deleted region of chromosome 1, and more research is needed to understand what role these genes play in neuroblastoma development. 
  • Thrombocytopenia-absent radius syndrome 
    • Everyone diagnosed with thrombocytopenia-absent radius (TAR) syndrome, which is characterized by bleeding problems and abnormal development of the forearms, has had a deletion of genetic material on chromosome 1. The deletion removes about 200,000 DNA building blocks (200 kilobases, or 200 kb) from the long (q) arm of the chromosome at position 1q21.1. This section of the chromosome contains 11 genes. The loss of multiple genes in this region is believed to be responsible for TAR syndrome. Not all people who inherit the deletion of genetic material on chromosome 1 associated with TAR syndrome will develop the disorder. Even within a single family, some people with the deletion may have TAR syndrome while others are unaffected. For this reason, researchers believe that the 1q21.1 200 kb deletion is needed to cause TAR syndrome but that some other, unknown genetic change must also be present. 
Diagramming Chromosome I
Below is an ideogram of Chromosome I, which shows its relative size and banding pattern. The banding pattern is the pattern of dark and light areas on the chromosome that are used to identify the location of genes on each chromosome.

1 comment:

  1. This website details all pattern and annotation changes that have been created to the Chromosome I methodical referrals pattern since its intial launch.