ChRoMoSoMe 16 AnD 21

Chromosomes.

A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing manygenes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.

    CHROMOSOME 16.......

Chromosome 16 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 16 spans about 90 million base pairs (the building material of DNA) and represents just under 3 % of the total DNA in cells.

    Diaseases and Disorders.

• Trisomy 16

Trisomy 16 is a chromosomal abnormality in which there are 3 copies of chromosome 16 rather than two.^[1] It is the most common chromosomal cause of miscarriage,^[2] and usually causes miscarriage in the first trimester of pregnancy.

• Red Hair

Red hair, also called ginger hair, occurs naturally on approximately 1–2% of the human population. It occurs more frequently in people of northern or western European ancestry, and less frequently in other populations. Red hair appears in people with two copies of a recessive gene on chromosome 16 which causes a mutation in the MC1R protein.

• Thalassemia

Thalassemia is a group of inherited autosomal recessive blood disorders that originated in theMediterranean region. In thalassemia the genetic defect, which could be either mutation or deletion, results in reduced rate of synthesis or no synthesis of one of the globin chains that make up hemoglobin. This can cause the formation of abnormal hemoglobin molecules, thus causing anemia, the characteristic presenting symptom of the thalassemias.

  Chromosome 21.....

Chromosome 21 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. The trisomy of the 21st chromosome causes Down Syndrome. Chromosome 21 is the smallest human chromosome, 47 million nucleotides (the building material of DNA) and representing about 1.5 percent of the total DNA in cells.

  Diaseases and Disorders.

• Alzheimer

Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death. It was first described by German psychiatrist and neuropathologist Alois Alzheimer in 1906 and was named after him.

• Homocystinuria

Homocystinuria is an inherited disorder of themetabolism of the amino acid methionine, often involving cystathionine beta synthase. It is an inherited autosomal recessive trait, which means a child needs to inherit a copy of the defective gene from each parent to be affected.

• Leukocyte adhesion deficiency

Leukocyte adhesion deficiency is a rare autosomal recessive disorder characterized by immunodeficiency resulting in recurrent infections. Leukocyte adhesion deficiency is divided into at least two subtypes: LAD1 and LAD2.