For more information, see table Some Sphingolipidoses Some Sphingolipidoses Lysosomal enzymes break down macromolecules, either those from the cell itself (eg, when cellular structural components are being recycled) or those acquired outside the cell. Inherited defects... read more and see table Other Lipidoses Other Lipidoses Lysosomal enzymes break down macromolecules, either those from the cell itself (eg, when cellular structural components are being recycled) or those acquired outside the cell. Inherited defects... read more .
See also Approach to the Patient With a Suspected Inherited Disorder of Metabolism Approach to the Patient With a Suspected Inherited Disorder of Metabolism Most inherited disorders of metabolism (inborn errors of metabolism) are rare, and therefore their diagnosis requires a high index of suspicion. Timely diagnosis leads to early treatment and... read more .
Niemann-Pick disease inheritance is autosomal recessive Autosomal Recessive Genetic disorders determined by a single gene (Mendelian disorders) are easiest to analyze and the most well understood. If expression of a trait requires only one copy of a gene (one allele)... read more and appears most often in Ashkenazi Jews; 2 types, A and B, exist. Type C Niemann-Pick disease Other Lipidoses Lysosomal enzymes break down macromolecules, either those from the cell itself (eg, when cellular structural components are being recycled) or those acquired outside the cell. Inherited defects... read more is an unrelated enzymatic defect involving abnormal cholesterol storage.
Children with type A have < 5% of normal sphingomyelinase activity. The disease is characterized by hepatosplenomegaly, failure to thrive, and rapidly progressive neurodegeneration. Death occurs by age 2 or 3 years.
Patients with type B have sphingomyelinase activity within 5 to 10% of normal. Type B is more variable clinically than type A. Hepatosplenomegaly and lymphadenopathy may occur. Pancytopenia is common. Most patients with type B have little or no neurologic involvement and survive into adulthood; they may be clinically indistinguishable from those with type I Gaucher disease Gaucher Disease Gaucher disease is a sphingolipidosis, an inherited disorder of metabolism, resulting from glucocerebrosidase deficiency, causing deposition of glucocerebroside and related compounds. Symptoms... read more . In severe cases of type B, progressive pulmonary infiltrates cause major complications.
Diagnosis of Niemann-Pick Disease
Both types are usually suspected by history and examination, most notably hepatosplenomegaly. Diagnosis of Niemann-Pick disease can be confirmed by DNA analysis and/or sphingomyelinase assay on white blood cells and can be made prenatally by using amniocentesis or chorionic villus sampling. DNA tests also can be done to diagnose carriers. (Also see testing for suspected inherited disorders of metabolism Initial testing Most inherited disorders of metabolism (inborn errors of metabolism) are rare, and therefore their diagnosis requires a high index of suspicion. Timely diagnosis leads to early treatment and... read more .)
