\"Decoding the genetics of Language\" A complex series of face and mouth movemen
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"Decoding the genetics of Language" A complex series of face and mouth movements are necessary for speaking fluently. In a three- generation pedigree of a British family (known as KE Family) half of the family members have difficulties with grammar, comprehension and speech- termed speech language disorder. The underlying disorder is termed "Childhood Apraxia", a result of the failure to co-ordinate muscle movements of mouth and face that are needed for speech. It is an autosomal dominant disorder with affected individuals being heterozygous for the gene in question. Based on the information above how many copies of a mutated gene will an individual need to inherit to confer the trait? In 2001, geneticists identified the cause of the inherited speech deficit in members of this family and attributed it 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. Turns out, FOXP2 is a transcription factor belonging to the winged helix transcription factor family characterized by a highly conserved Forkhead (Fox) domain that binds to distinct DNA sequences in its target gene's regulatory regions. The mutation within the affected members of the family lies in a single point mutation such that G-A transition changes the amino acid from R553H (R at the 553 position to H) affecting it's ability to bind to DNA. FOXP2 is expressed (the protein is found) in many tissues, during development including parts of the brain, the lung, the gut and the heart. Yet, members of the KE family only seem to show deficits confined to regions of the brain implicated in speech development that manifests as speech apraxia. Give one possible explanation for why that may be?Explanation / Answer
Based on the information above how many copies of a mutated gene will an individual need to inherit to confer the trait
Childhood Apraxia is an autosomal dominant disorder, so person needs only one copy to express the disease condition. For example allele A is responsible for the condition childhood Apraxia, then both AA and Aa will express the condition.
One copy of a mutated gene will an individual need to inherit to confer the trait.
Give one possible explanation for why that may be keeping in mind the nature of the inheritance
Here the individuals are heterozygous for the given condition, means these people have two copies of FOXP2 gene, as this KE family has one defective copy of FOXP2 and one normal copy of FOXP2 gene, the protein produced from normally functioning FOXP2 gene is enough for them to have normal development of lungs, gut and heart, but half the usual dosage of normally functioning FOXP2 protein might not be adequate for their brain to develop to have proper speech.
That is the reason why its effect has confined to regions of the brain without affecting the other parts of the body.
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