what chromosome has the genetic mutation for huntington's disease
Huntington's disease HD is one of several trinucleotide repeat disorders which are caused by the length of a repeated section of a gene exceeding a normal range.[25] The HTT gene is located on the short arm of chromosome 4[25] at 4p16.3. HTT contains a sequence of three DNA bases—cytosine-adenine-guanine (CAG)—repeated multiple times (i.e. ... CAGCAGCAG ...), known as a trinucleotide repeat.[25] CAG is the 3-letter genetic code (codon) for the amino acid glutamine, so a series of them results in the production of a chain of glutamine known as a polyglutamine tract (or polyQ tract), and the repeated part of the gene, the PolyQ region.[26]
Huntington's disease HD is typically inherited from a person's parents, although up to 10% of cases are due to a new mutation.[1] The disease is caused by an autosomal dominant mutation in either of an individual's two copies of a gene called Huntingtin.[4] This means a child of an affected person typically has a 50% chance of inheriting the disease.[4] The Huntingtin gene provides the genetic information for a protein that is also called "huntingtin".[1] Expansion of CAG (cytosine-adenine-guanine) triplet repeats in the gene coding for the Huntingtin protein results in an abnormal protein, which gradually damages cells in the brain, through mechanisms that are not fully understood.[4] Diagnosis is by genetic testing, which can be carried out at any time, regardless of whether or not symptoms are present.[5] This fact raises several ethical debates: the age at which an individual is considered mature enough to choose testing; whether parents have the right to have their children tested; and managing confidentiality and disclosure of test results.[2]
Alonso Álvarez de Pineda
Marcus Álvarez