Introduction Hepatosplenomegaly is often present in infantile Sanshoff disease. However, cardiac involvement is extremely uncommon. Case report We describe a 14-month-old female baby who exhibited mitral regurgitation and cardiomegaly at the age of 2 months, dilation of the left atrium and left ventricle at age of 6 months, followed by regression of developmental milestones after an episode of minor infection at age of 14 months. Brain magnetic resonance imaging revealed signal changes over the bilateral thalami, bilateral cerebral white matter and left putamen. An examination of the fundus showed presence of cherry-red spots in both macular areas. The lysosomal enzymatic activities showed a marked reduction of β-hexosaminidase B (HEXB) activity. Two novel mutations of HEXB gene were identified. One of the mutations was a c.1538 T > C mutation, which predicted a p.L513P amino acid substitution of leucine to proline; the other was a c.299 + 5 G > A mutation, which was a splice site mutation. Conclusion Cardiac involvement might occur prior to neurological symptoms in infantile Sandhoff disease, and it should be included in the differential diagnoses of metabolic cardiomyopathies in the infantile stage.
