1) revealing diffuse leukodystrophy, basal ganglia and cerebellar atrophy, along with a thin corpus callosum, suggestive of hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC syndrome), a syndrome first described in 2002. Serial detailed phenotyping allowed recognition of childhood-onset, progressive, combined, dystonia as our patients gradually developed the typical disease milestones of dystonia, cerebellar signs and whispering dysphonia. Keywords: H-ABC syndrome; TUBB4A; TUBB4A-related disease; whispering dysphonia EN H-ABC syndrome TUBB4A TUBB4A-related disease whispering dysphonia S54 S57 4 08/28/23 20230802 NES 230802 We describe two sisters in whom careful characterization of movement disorder phenomenology and recognition of evolving biomarkers were key diagnostic factors after 30 years of follow-up. [Extracted from the article]