Altered red cell osmotic fragility in Huntington disease (HD).

We have studied in fresh and 24-hour incubated samples the osmotic fragility of erythrocytes from 13 individuals with Huntington disease (HD) and 22 at-risk, asymptomatic individuals. Five older at-risk, asymptomatic individuals and six Alzheimer disease individuals were also studied. Results suggest that osmotic fragility of red cells from HD individuals in significantly decreased in fresh (P less than 0.0001) and incubated (P less than 0.0001) samples. At-risk individuals appear to fall into two groups: 1) those with normal osmotic fragility (n =10), and 2) those with decreased osmotic fragility (n = 12). Fragility in older at-risk persons and those with Alzheimer disease were within normal limits. These data suggest that red cell osmotic fragility measurement may be useful to identify at-risk persons with an HD gene; however, longitudinal follow-up will be required to confirm the predictive power of this observation. These data suggest additional support for focusing on the erythrocyte in investigating the molecular pathogenesis of HD.