In 2001, geneticists identified linked the inherited speech deficit in members of this family and to a mutation within a single gene FOXP2. (Cecilia S. L. Lai, Simon E. Fisher, Jane A. Hurst, Faraneh Vargha-Khadem and Anthony P. Monaco; Nature 413, 519-523(4 October 2001) This was exciting news as no ‘gene’ had ever been associated with a complex trait such as language. FOXP2 is a transcription factor belonging to the winged helix transcription factor family. It has a well characterized DNA binding domain [ Forkhead (Fox) domain] that binds to distinct DNA sequences within target gene promoters. The mutation within the affected members of the family is a G-A transition mutation that changes the amino acid from R553H (R at the 553 position becomes H). This single mutation prevents the ability of the transcription factor to bind DNA.
a) FOXP2 is expressed (the protein is found) in many tissues during development, including parts of the brain, lung, gut and the heart. Yet, members of the KE family only show deficits confined to regions of the brain implicated in speech development that manifests as speech apraxia. Give one likely explanation for why that may be. Think about the role of FOXP2 and/or the nature of the inheritance
b)Additional research on FOXP2 discovered that the gene (and protein) is not unique to humans. The gene is found in a diverse array of animal species- birds, bats and bees. The human FOXP2 differs from our closest relatives the chimpanzees, gorillas and rhesus macaques by just 2 amino acids and from that found in mice by only 3 amino acids! What this tells us is that through evolution a few amino acids provided some advantage to the way language evolved and possibly the difference between the ‘uniquely human’ ability- language and the rest of the animal kingdom. Based on this information alone which of the following would make sense:
A. If a mouse FoxP2 gene is removed, the mouse might “talk.”
B. Feeding mice the three amino acids that differ between human and mouse might enable the mice to “talk.”
C. Replacing the mutated human FOXP2 gene with a mouse FoxP2 gene is a way to cure speech disorders.
D. Putting the human version of FOXP2 gene into a mouse might enable it to form more complex sounds similar to human language.
c) Researchers are interested in understanding how mutations in FOXP2 lead to problems with speech. Insight can be gained by learning more about what the normal function of FOXP2 is. Describe an experiment you would do to attempt to answer the question “What genes are regulated by FOXP2 in the brain”. Assume you have all the possible cell lines you need. You need to outline your thought process that demonstrates you have understood the use of the technique.