What genetic abnormality is responsible for the disorder? HD is called an autosomal dominant disorder because only one copy of the defective gene, inherited from one parent, is necessary to produce the disease. The genetic defect responsible for HD is a small sequence of DNA on chromosome 4 in which several base pairs are repeated many, many times.

On to which chromosome/s has the genetic abnormality been mapped? The HD gene, whose mutation results in Huntington disease, was mapped to chromosome 4 in 1983 and cloned in 1993. The mutation is a characteristic expansion of a nucleotide triplet repeat in the DNA that codes for the protein huntingtin.

What is the phenotype of an individual with the disorder? Careful comparison of symptomatic individuals with normal controls has revealed the primary biochemical abnormality in many human genetic diseases, particularly recessive disorders.

How is the disorder diagnosed? Is there a routine genetic test?Huntington's disease is caused by an inherited defect in a single gene. Huntington's disease is an autosomal dominant disorder, which means that a person needs only one copy of the defective gene to develop the disorder.

What treatment options are available for individuals affected by the disorder?No treatments can alter the course of Huntington's disease. But medications can lessen some symptoms of movement and psychiatric disorders.

Is the disorder heritable? Can it be passed onto future generations?This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. ... Individuals who have 27 to 35 CAG repeats in the HTT gene do not develop Huntington disease, but they are at risk of having children who will develop the disorder.