All forms of NPD are inherited autosomal recessive disorders, requiring the presence of an inherited genetic mutation in only one copy of the gene responsible for the disease. Both males and females are affected equally.
A diagnosis of Niemann-Pick disease is confirmed by analyzing a sample of tissue.
At least five different forms of Niemann-Pick disease (NPD) have been identified.
Type A is the most common form of NPD and the most serious, with death usually occurring by the age of 18 months.
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Ultimately, the nervous system becomes severely damaged and patients with Types C and D Niemann-Pick disease die.
Some adults with Niemann-Pick disease (Type E) may also show a loss of muscle coordination.
Both Niemann-Pick disease types A and B occur in many ethnic groups; however, they occur more frequently among individuals of Ashkenazi Jewish descent than in the general population.
type A (NPD A), the acute infantile form; type B (NPD-B), a less common, chronic, non-neurological form; and type C (NPD-C), a biochemically and genetically distinct form of the disease.
A carrier for Niemann-Pick disease typically has a heterozygous genotype, meaning they possess one normal allele and one mutated allele for the NPC1 or NPC2 gene, depending on the specific type of Niemann-Pick disease. This genotype can be represented as "N/n," where "N" denotes the normal allele and "n" the mutated allele. Carriers usually do not exhibit symptoms of the disease but can pass the mutated allele to their offspring.
Treatment consists of supportive care to deal with symptoms and the development of complications.
Approximately 40% of people with retinoblastoma have an inherited form of the condition and approximately 60% have a sporadic (not inherited) form.
The different types seem to be related to the activity level of the enzyme sphingomyelinase.