Niemann-Pick disease type C (NPC) an ultra-rare and neurodegenerative disease caused by mutations in the NPC gene (NPC1 or NPC2). Mutations in NPC gene lead to reduced production of protein in cells responsible for transporting materials throughout the cell. When the protein is reduced, there is a toxic accumulation of lipids in the cells. NPC can be diagnosed at any age, however, more severe disease affects infants and young children. Diagnosing NPC can be difficult as young children may often appear healthy at birth and develop normally for several years – the exact number of years is variable for each child. Generally speaking, the younger a child is diagnosed with the disease the faster the disease progression is expected to be. Over time, development will slow, stop, then children begin to lose their skills and regress. Slowly the disease takes away a child’s ability to walk, talk and move. Eventually, swallowing and breathing becomes affected which often leads to death through complications such as aspiration and pneumonia. Presently NPC is always fatal and many children diagnosed early in life will not live to see their 10th birthday.
If NPC is suspected or a medical condition is present and unknown, DNA testing may occur. DNA testing is available as single gene testing (if mutations are suspected or known in a specific gene), panel testing (may look at several genes that may contribute to a specific medical concern) or exome testing (looks at all the genes in the DNA). If mutations are identified in the NPC gene, this does not automatically mean they are disease causing. Secondary testing (skin biopsy or blood test) is often required to further confirm NPC disease.
Diagnosis may also be confirmed by skin biopsy in Canada. A small piece of skin is removed and sent to a lab that will test to see if there is an accumulation of the lipids within the cell. These specialized labs are located in the United States so confirmation of diagnosis via skin biopsy can delay diagnosis for up to 6 weeks.
In the United States, there is a blood test that can confirm a diagnosis of NPC however, this is not yet available in Canada.