OMIM ID:
Niemann-Pick Disease, Type C2
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
The primary ocular feature of type C2 Niemann-Pick disease is supranuclear gaze palsy. A cherry red spot is rarely seen.
Systemic Features
Neurodegeneration is the outstanding clinical manifestation and often the cause of death. The onset usually occurs in infancy and the course is rapid with death often in the first year of life. The clinical disease is similar to that of the more common type C1 (257220) although there is considerable clinical heterogeneity in all types of NPC. Pulmonary involvement can be a prominent feature of C2 disease. Other neurologic symptoms include ataxia, facial dyskinesis, bradykinesia, expressive aphasia, dysarthria and cognitive decline. Visceromegaly seems to be less common than in type C1 (257220). Cholesterol esterification is impaired with accumulation in intracellular organelles.
Genetics
Inheritance
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.