Neuraminidase deficiency is a medical condition caused by insufficient amounts of neuraminidase, a glycoside hydrolase enzyme, which is known to one of the enzymes present on the surface of the Influenza virus. Deficiency of neuraminidase results to the development of a rare lysosomal storage disease called sialidosis.

Symptoms may be present at birth or develop within the early years of life, which presents the following manifestations: * Infants born with neuraminidase deficiency present excessive swelling throughout the body especially noted immediately at birth. * Many infants born with this deficiency are born with coarse facial features including flat nasal bridge, enlarged gums, puffy eyelids, macroglossia (excessively large tongue). * Skeletal anomalies like hip dislocation * Myoclonus (sudden involuntary muscle contraction) * Red spots in the eyes ( called cherry-red macules) * Impaired voluntary movement coordination * Tremors * Seizure * Impaired vision * Clinical tests uncover liver or spleen enlargement noticeable due to abdominal swelling * Absence or lack of muscle tone (Hypotonia) * Severe mental retardation * Recurrent respiratory infections * Failure to thrive * Most infants with this disease die before they turn 1-year-old.

Neuraminidase deficiency is caused by inadequate amount of the enzyme neuraminidase.