Dysphonia is a common speech disruption in people with Parkinson's (PD) and Huntington's (HD). Though the glottal source analysis (GSS) yielded promising results in PD, no study analyzed utility of the GSS in HD. In addition, the potential GSS sex-dependency remains unknown. This study examines sustained vowel phonations provided by 40 PD, 40 HD and 40 age- and sex-matched healthy participants using six GSS features including normalized amplitude quotient, quasi-open quotient, magnitude difference of first two spectral peaks, harmonic richness factor, maximum dispersion quotient (MDQ), and peak slope. Our results showed significant differences in HD men and women compared to the healthy counterpart, suggesting breathiness (p<0.01), tension (p<0.001), and decreased timbre (p<0.01) in HD. Reported sex-related differences highlighted the sensitivity of the GSS towards the speaker's sex. The correlation analysis revealed significant relationship between disease severity and MDQ in HD men.