Huntingtons-Disease




 * Genetic background/significance:**
 * ====All humans have the Huntintin gene (//HTT//) which codes for the protein Huntintin (Htt) ====
 * ====Part of the gene is a **trinucleotide repeat **—how long the repeat reaches produces an altered protein called “mutant Huntingtin protein (mHtt)” ====
 * ====Length of the repeated section reflects the severity ====
 * ====Changes to the protein cause the changes that become disease symptoms ====

Huntington’s disease is a genetic disease that is progressive and degenerative disease that causes certain nerve cells in the brain to waste away which causes uncontrolled movements, emotional changes, and mental deterioration. It is generally a late onset disease with symptoms arising around middle age, but there are early onset cases which results in more severe symptoms. There are no treatments, but medications can be used to decrease the severity of symptoms such as chorea.
 * Description:**


 * Symptoms:**
 * Dementia: loss of brain function; affects memory, thinking, language, judgment, and behavior
 * Chorea: uncontrollable jerky movements
 * Rigidity, writhing motions, or abnormal posture

Once you pass the threshold of say 36-40 but with maybe 42 repeats, you would have late onset HD but with the more repeats of this mutated gene, the earlier symptoms would arise and the more severe they will be. Also, this disease is not inherited according to sex, but the length of the repeat can be influenced by the sex of the affected parent.
 * Important detail from AP Biology perspective:**
 * Classification of the trinucleotide repeat, and resulting disease status, depends on the number of CAG repeats ||
 * **Repeat count** ||  **Classification**  ||  **Disease status**  ||
 * <28 ||  Normal  ||  Unaffected  ||
 * 28–35 ||  Intermediate  ||  Unaffected  ||
 * 36–40 ||  Reduced Penetrance  ||  +/- Affected  ||
 * >40 ||  Full Penetrance  ||  Affected  ||


 * Pattern:**
 * ==== Autosomal dominant pattern: caused by an abnormal autosomal dominant allele (genetically dominant) ====
 * ==== Mutation of either of a person's //HTT// genes causes the disease. ====

//By Jennifer and Megan//
 * Sources:**
 * **[]**
 * **Image: []**