Abstract: Objective　To explore the clinical and HEXB gene mutation characteristics of infantile Sandhoff's disease. Methods　The clinical data of 2 probands of infantile Sandhoff disease and their families were retrospectively analyzed. Results　The onset in two probands (one male, one female) was in infancy. The first manifestation was hypoplasia and the common manifestations were excessive fright, epilepsy, tendon reflex enhancement, cherry red spot on the fundus of the eye, etc. Progressive developmental regression occurred in both children, and almost all motor and cognitive abilities were lost around the age of 2 years. Cranial MRI showed that the male patient had no abnormalities and the female patient had abnormal signals in bilateral basal ganglia and cerebellar atrophy. The heterozygous and homozygous mutations were found in HEXB gene of 2 children, and the mutant sites were reported for the first time. The boy died in preschool age and the girl is still in follow-up. Conclusions　Mental motor retardation and regression are the earliest and most common manifestations of infantile Sandhoff disease. Abnormal signals in thalamus and basal ganglia may be its characteristic manifestations. Myelodysplasia and brain atrophy are also common. Gene testing is helpful for diagnosis.

Key words: Sandhoff disease;　HEXB gene;　cherry red spot;　infant