SM accumulation is 4 to 6 times normal and enzyme activity is normal. Niemaoh-Pick disease (NPD), also known as sphingomyelin lipidosis, is a congenital disorder of glycolipid metabolism. It is characterized by elevated serum mucin (SM) accumulation. What is the differential diagnosis of elevated SM accumulation? The following is an explanation for you. 1. Acute neurological type (type A or infantile type) is typical of Niemann-Pick (85% of cases), mostly within 3-6 months after birth, with a few onset a few weeks after birth or after 1 year of age. Initially, the disease is characterized by loss of appetite, vomiting, feeding difficulties, extreme emaciation, dry waxy yellow skin, progressive mental and motor decompensation, hypotonia and floppy paralysis, and eventually idiocy. Half of the cases have cherryred?spot under the eyes, blindness, and jaundice with hepatosplenomegaly. They are anemic and cachectic, and most die before the age of 4 years due to infection. The skin often shows a small yellow verrucous rash with deafness. The accumulation of neurospinal phospholipids is 20-60 times higher than normal, and the enzyme activity is 5-10% of normal, with a minimum of <1%. 2, non-neurological type (beta type or visceral type) Infancy or childhood onset of open door, slow progression of disease, prominent hepatosplenomegaly. Normal intelligence, no neurological symptoms. SM accumulation is 3-20 times normal, enzyme activity is 5-20% of normal, low as in type A. 3. Juvenile type (C chronic neurological type) Most often seen in children, a few young children or adolescents. Postnatal development is mostly normal, and a few have early jaundice. The first hepatosplenomegaly often occurs, and most of the neurological symptoms appear at the age of 5-7 years (or earlier or as late as young adulthood). Mental retardation, language disorders, learning difficulties, emotional changes, unsteady gait, ataxia, tremor, hypertonia and tendon reflexes, convulsions, dementia, and cherry erythema or supranuclear vertical oculomotor paresis are seen in the fundus. SM accumulation is 8 times higher than normal, and enzyme activity is up to 50% of normal, or close to normal or normal. 4.Nova-scotia type (D type) Clinical course is slower than juvenile type, with marked jaundice, hepatosplenomegaly and neurological symptoms, and death mostly at school age, with reduced enzyme activity. 5. Adult type Adult onset, normal intelligence, no neurological symptoms, varying degrees of hepatosplenomegaly. SM accumulation is 4-6 times normal and enzyme activity is normal. It is a deficiency of sphingomyelinase that leads to impaired metabolism of sphingomyelin. The latter accumulates in the mononuclear macrophage system, resulting in hepatosplenomegaly and degenerative changes in the central nervous system.