Question

A 32-year-old Caucasian man underwent testing for Huntington’s Disease. The patient was a lively and talkative child who completed high school with As and Bs and college with poor grades. At age 22 he became quiet and non-conversant. At age 24 he began work as a cook/dishwasher and displayed noticeable un-coordination. At age 28 he developed dysarthria, dysphagia, stiffness, slow ataxic gait, and dementia. There was no history of schizophrenia or depression and the neurological review of systems was negative. Both parents were in their late 60s and in excellent health, without signs of dementia. There was no history of any neurodegenerative disease and he had three sisters, aged 35-37, all in good health.

Laboratory Results:

Creatine phosphokinase: Normal

Vitamin E: Normal

Lactate: Normal

Pyruvate: Normal

Imaging Results:

MRI: Generalized, cerebral and cerebellar atrophy

​​Very mall caudate nuclei

HIstology Results:

Skin biopsy: Normal mitochondria

Bone Marrow and Enzyme Screen:

Human Granulocyte-Macrophage: Normal

Metachromatic Leukodystrophy: Normal

Krabbe’s disease: Normal

Physical examination:

Mini-mental status exam: 20/26

Cranial nerve exam: decreased upgaze, saccadic extraocular eye movement, dysarthria and hyperactive gag reflex

Strength: Normal

Gait: wide-based and ataxic

Molecular Test Results:

Diagnostic HTT molecular test for patient:

​​​1 band representing 23 CAG repeats

​​​1 band representing 49 CAG repeats

HTT molecular test for father:

​​​1 band representing 20 CAG repeats

​​​1 band representing 37 CAG repeats

HTT molecular test for mother:

​​​1 band representing 17 CAG repeats

Predictive HTT molecular test for sister:

​​​1 band representing 17 CAG repeats

​​​1 band representing 20 CAG repeats

What testing methodology would be used to evaluate the repeat sizes for the patient and the family?

Is any confirmation needed? If so, why and which testing methodology should be used?

Answer 1

Based on the symptoms, The underlying disorder can be Parkinsons disease.

No specific test exists to diagnose Parkinson's disease. Your doctor trained in nervous system conditions (neurologist) will diagnose Parkinson's disease based on your medical history, a review of your signs and symptoms, and a neurological and physical examination

Imaging tests — such as an MRI, ultrasound of the brain, and PET scans — also may be used to help rule out other disorders. Imaging tests aren't particularly helpful for diagnosing Parkinson's disease.

In addition to your examination, your doctor may can give carbidopa-levodopa (Rytary, Sinemet, others), a Parkinson's disease medication. He must be given a sufficient dose to show the benefit, as low doses for a day or two aren't reliable. Significant improvement with this medication will often confirm your diagnosis of Parkinson's disease.

Sometimes it takes time to diagnose Parkinson's disease. Doctors may recommend regular follow-up appointments with neurologists trained in movement disorders to evaluate your condition and symptoms over time and diagnose Parkinson's disease.