To describe a brain metabolic network selectively expressed in symptomatic Huntington's disease (HD) gene carriers.A metabolic network specifically associated with HD motor symptoms may be useful in assessing new therapies. We used PET imaging and network analysis to identify a spatial covariance pattern expressed in newly symptomatic HD patients.We utilized serial FDG PET to study 12 presymptomatic HD gene carriers at baseline, 18, and 44 months. Four subjects became symptomatic by 44 months. Additionally, two phenoconverters and two non-phenoconverters were scanned at 68 months. To identify a symptom-related pattern, we conducted network analysis to compare the phenoconverted and non-phenoconverted scans at 44 months. Scans from 12 age-matched healthy controls were included for comparison.We identified an HD symptom-related metabolic covariance pattern (HDSP), which separated symptomatic and preclinical gene carriers (p < 0.01). This pattern was characterized by increased metabolism in the primary motor and premotor cortex associated with ventral thalamic reductions. The early symptomatic patients exhibited elevated HDSP expression at 44 months, which increased further at 68 months. Network activity in the non-phenoconverted subjects remained in the range of healthy controls at both time points. Interestingly, computation of HDSP expression retrospectively in scans acquired at baseline and 18 months revealed that network activity was already elevated (p < 0.01) in the preclinical HD subjects who subsequently phenoconverted versus those who did not. Across all subjects and time points, pattern activity correlated with UHDRS motor ratings (p < 0.02).The HDSP network emerged as preclinical HD subjects neared clinical onset; its expression also increased as symptoms progressed. A unique feature of the HDSP is its high sensitivity for the motor symptoms of HD. The correlation of pattern activity with clinical ratings indicates that this network may be particularly useful in assessing the emergence of HD symptoms and their response to therapy.