E-table 1 Factors influencing clinical progression in HD, review of the literature

Author / # Patients / Study Type / Measures / Observations / Conclusion
Claes 199527 / 59
/ Retrospective / Medical records / None / Factors that determine the nature of onset and the mode of progression are independent of the CAG repeat
Roos 199328 / 1106 / Retrospective / Medical records / None / Age of onset and duration of illness are not related. Duration shorter for males, especially paternal transmission males.
Foroud 199929 / 2068 / Retrospective / Affected Questionnaire, confirmed by medical records and death certificates / None / Duration of disease is influenced by the age at symptom onset, with juvenile and late onset patients having the shortest duration.
Jason 199730 / 50 HD, 127 at risk / Prospective / Neuropsychological Tests / One / More repeats associated with worse performance over time, but small effect compared to duration alone
Illarioshkin 199431 / 28 / Prospective / QNE, MMSE, CT or MRI / One / Significant correlation between rate of progression of clinical symptoms and CAG repeat length
Buruma 198732 / 51 / Retrospective / Symptoms at onset , course of illness, SES, Life Habits, DSM III, SF stage / One / Early age at onset associated with slower progression in adult onset cases
Penney 199711 / 89 brains / Retrospective / Vonsattel grade / One / Linear correlation between CAG number and grade/age at death
Antonini 199833 / 8 symptomatic, 10 asymptomatic / Prospective / [11C] raclopride and positron emission tomography / One / a high correlation between CAG repeat length and the ratio of percent loss in striatal D2 receptor binding divided by age
Ashizawa 199434 / 36 / Prospective / Physical Disability Rating Scale / One / The rate of disease progression does not correlate with CAG repeat size or age at onset.
Feigin 199512 / 129 / Prospective / TFC, chorea and dystonia scores / >=2, best fit line / No correlation between rate of functional decline and age at onset of HD
Kieburtz 199414 / 54 / Prospective / TFC / >=2, best fit line / No relationship between CAG repeats and rate of clinical decline.
Aylward 19979 / 23 / Prospective / Cross-sectional MRI, QNE / >=2 MRI images at least 10 months apart. / Rate of atrophy is greater for patients with earlier onset and greater CAG length. Increased basal ganglia atrophy is associated with greater disease severity.
Marder 200017 / 960 / Prospective / TFC, Independence Scale / two to seven / longer disease duration and better cognitive status associated with a less rapid decline. No effect of age at onset of HD, sex, weight, and education.
Mahant 200318 / 815 / Prospective / UHDRS, TFC / >=2, linear model / Younger onset associated with more rapid motor, cognitive and functional progression.
Brandt 199610 / 67 / Prospective / QNE, MMSE, ADL / Three / The length of the CAG repeat was a strong predictor of decline in both neurologic & cognitive function.
Myers 199135 / 42 / Prospective / Neurological examination, Disability Scale / >=6, best fit line / Slow progression associated with late age at onset of disease.