¹⁸F-FDG PET Identifies Altered Brain Metabolism in Patients with Cri du Chat Syndrome

Cri du chat syndrome (CDCS) is a rare genetic disease that is caused by a deletion in the short arm of chromosome 5 (5p) and has a variable clinical spectrum. To our knowledge, no study in the literature has ever applied ¹⁸F-FDG PET/CT to investigate alterations in brain glucose metabolism in these subjects. The aims of this study were to detect differences in brain ¹⁸F-FDG metabolism in CDCS patients with different clinical presentations and identify possible brain metabolic phenotypes of this syndrome. Methods: Six patients (5 male and 1 female; age range, 10-27 y) with CDCS were assessed for the presence of cognitive and behavioral symptoms using a battery of neuropsychologic tests and then classified as having either a severe or a mild phenotype. The patients then underwent brain ¹⁸F-FDG PET/CT. The PET/CT findings were compared with an age- and sex-matched control group using statistical parametric mapping (SPM). Whether there was an association between different clinical phenotypes and ¹⁸F-FDG PET/CT findings was investigated. Results: Four patients had the severe phenotype, and 2 patients demonstrated the mild phenotype. SPM single-subject analysis, and a group analysis in comparison with the control cohort, revealed significant hypometabolism in the left temporal lobe (Brodmann areas [BAs] 20, 36, and 38), in the right frontal subcallosal gyrus (BA 34) and caudate body, and in the cerebellar tonsils (P < 0.001). Hypermetabolism (P = 0.001) was revealed in the right superior and precentral frontal gyrus (BA 6) in the patient group, compared with the control cohort. In SPM single-subject analysis, the hypermetabolic areas were detected only in patients with the severe phenotype. Conclusion: This study revealed different patterns of brain glucose metabolism in patients with the severe and mild phenotypes, compared with control subjects. In particular, abnormal hypermetabolism in the brain, as evaluated by¹⁸F-FDG PET/CT, seems to correlate with the severe CDCS phenotype.