CAG: The death chain

Many neurodegenerative diseases, including Parkinson’s, Alzheimer’s, and Huntington’s, result from progressive loss of structure or function of neuron cells.  A large number of neurodegenerative diseases are caused by genetic mutations. In the case of Huntington’s disease, the mutated gene contains a repeat of the CAG nucleotide triplet. C, A and G represent three out of four different nucleotides in DNA strands, which encode amino acid glutamine. A repeat of CAG results in a polyglutamine tract. The polyglutamine-tract proteins are deleterious and may cause the death of neurons. In this picture, a neuron cell is being choked by an iron chain. The chain is made of the letters “ CAG”, which represents metaphorically the cause of neuron cell damage in Huntington’s disease - the CAG repeat in the mutated gene. The green blob inside the neuron represents the protein aggregate formed by disease-associated proteins, which are commonly seen in neurodegenerative diseases.