Huntington disease (HD) is a neurodegenerative condition of progressive chorea, cogwheel rigidity, and dementia found in both men and women, typically with onset in adulthood. The incidence is estimated at 1 in 10,000.

Clinical features: Huntington disease is characterized by involuntary movements, an unsteady gait, and cognitive and emotional disturbances. HD begins gradually, generally either with a change in gross motor activity (clumsiness, fidgety movements) or with a change in behavior (uncharacteristic anger, depression).

Over a 10-25 year period HD becomes more severe, progressing to uncontrollable ceaseless movements of the head, trunk and limbs. Speech becomes difficult to understand and swallowing is difficult. Some people with HD experience personality changes, impaired judgement, confusion, or forgetfulness. Death follows, most frequently caused by pneumonia due to an inability to cough effectively. The most common age of onset is between 30 and 50 years of age, although symptoms have appeared as young as 2 and as old as 70.

Inheritance: Autosomal dominant. Affected individuals have a 50% chance to pass the gene to each of their offspring.

Mutation information: The mutation in the huntingtin gene is an expansion of a CAG trinucleotide repeat in excess of 39 repeats. An association has been reported between the size of the repeat and the age of onset, however there is not enough data to support genotype:phenotype prognoses at this time.

Indications and benefits: Direct DNA testing is now recommended for confirmation of a diagnosis of HD with or without a family history of this condition. People at risk for HD who do not clearly carry a clinical diagnosis of HD are strongly recommended to be tested through a counseling program approved by the Huntington Disease Society of America. The pre-symptomatic testing protocol is designed to allow at-risk individuals to prepare for the outcome of genetic testing. A special consent form for HD testing must be completed prior to testing.

Test methodology: Samples are amplified for the HD gene region (4p16.3) by extended polymerase chain reaction (E-PCR)* and sized on a gel.

Turnaround: Routine 2-3 weeks, Rush 7-10 days

Additional resources: Huntington Disease has many complex genetic issues. We recommend consultation with a Genetic Counselor in your area, or you may call to 021-88003811-12