The primary diagnosis is made as based on the presence of unequivocal main signs of HD such as:

 

• Cognitive and neuropsychiatric symptoms such as personality changes, depression, cognitive decline… Patterns of behaviour and thinking, emotional state, judgment performance are evaluated.

 

• Progressive motor disability and altered voluntary movement. Reflexes, muscle tone and strength, hearing, balance, coordination, vision, mental status and mood are evaluated.

 

• Autosomal dominant pattern of inheritance in the family

 

Molecular genetic testing is performed to confirm the diagnosis. The main age of onset is 35 to 44 years of age, but in 25 % of cases the age of onset is 50 years of age.

 

 

Symptoms by order of appearance 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Molecular Genetic Testing

 

CAG repeats test determines the risk status for HD. Motor examination should be performed to determine age of onset and diagnosis. The commencement of changes in patients begins ten or twenty years prior to the age of onset. (Rupp et al, 2010) 

 

Huntingtin gene is the only gene associated with HD. Molecular testing of huntingtin gene could be performed in order to determine the number of CAG repeats and to prediagnose patients bearing CAG expansion.

 

This test is based on targeted mutation analysis. A PCR should be performed to detect alleles untill 115 CAG repeats and a Southern blot to identify large expansions associated with Juvenile-onset HD and to confirm homozygous normal. The mutation detection frequency of this test method is 100 %.