Missense, Nonsense & Deletions: The Genetics behind the Condition
The best way for us to explain how you "get" NPC is to explain how Chase "came down with it."
Our little champion swimmer made a splash in the usual way, combining chromosomes and DNA and RNA and other little scientific-sounding bits to become our Chase. As the miracle of life began Chase inherited a mutated chromosome 18 pair, one damaged chromosome 18 came from each parent (you have a pair of each chromosome in your body.) This happened because Mom and Dad each have one mutated chromosome 18 and one normal chromosome 18. Neither of Chases's parents has NPC but each carry one defective gene. In each pregnancy where both parents carry the defective gene there is a 25% chance the resulting bundle of joy will have Niemann Pick C. Someone must receive both mutations to have Niemann Pick C. The child has a 50% chance of just getting one mutation and being a carrier and a 25% of not having either mutation at all. A decade ago there was no way to test inutero for the disease, it is now possible. When a specific mutation is known, as ours are, then it is possible for concerned family to be tested for the specific mutation. Genetic Testing is quite expensive and not all insurance carriers will cover preventative genetic testing (for lack of a better way to word it.) Thus far approximately 20% of the gene has been mapped. There are 300 known NPC mutations since the disease was discovered. Because there are so many different mutations and so many still unknown it is very difficult to determine how fast the disease will progress. There is a mutation registry for Niemann Pick here Not all mutations are logged, ours are not inputted yet.