Chromosome 12 (human)

Chromosome 12 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 12 spans about 133 million base pairs (the building blocks of DNA) and represents between 4 and 4.5 percent of the total DNA in cells.

Structure

The structure of chromosome 12 is key to its function and its role in the human body. Like other chromosomes, it consists of a long strand of DNA wound around proteins called histones, forming a compact and organized structure that fits within the cell nucleus. This organization is crucial for the processes of DNA replication, DNA repair, and the transcription of genes into RNA.

Genes

Chromosome 12 contains between 1,200 and 1,300 genes. These genes are involved in a wide range of bodily functions and processes. Some of the notable genes on chromosome 12 include:

• PAH - This gene is responsible for the enzyme phenylalanine hydroxylase, which plays a critical role in the metabolism of the amino acid phenylalanine. Mutations in this gene can lead to phenylketonuria, a metabolic disorder.
• KRAS - An oncogene that plays a role in the signaling pathway regulating cell division. Mutations in KRAS can lead to cancer.
• NANOG - A gene involved in stem cell pluripotency. It is a key factor in maintaining the ability of embryonic stem cells to differentiate into any other cell type.

Genetic Disorders

Several genetic disorders are associated with mutations in genes on chromosome 12. These include:

• Phenylketonuria (PKU) - Caused by mutations in the PAH gene, leading to an inability to metabolize phenylalanine, resulting in intellectual disability and other problems if untreated.
• Lymphedema-distichiasis syndrome - A rare condition characterized by lymphedema and abnormal growth of eyelashes, among other symptoms.
• Pallister-Killian syndrome - A developmental disorder caused by the presence of an extra copy of part of chromosome 12, leading to intellectual disability, distinctive facial features, and other physical abnormalities.

Research

Research on chromosome 12 continues to uncover its secrets and the implications for human health and disease. Studies of the chromosome's structure, function, and role in genetic disorders are ongoing, with the aim of developing better diagnostic, treatment, and prevention strategies.

See Also

• Genetics
• Human genome
• Chromosomal abnormality