Confidence votes 11. According to Wikipedia, the width of the Atlantic Ocean at its narrowest point is 2,848 kilometers (1,770 mi) between Brazil and Sierra Leone.
What causes PNH? It is not fully understood why people develop PNH. Inside the bone marrow, blood cells are made by stem cells (the seed cells of the marrow). PNH occurs due to a change (or mutation) in a gene in one of the stem cells in the bone marrow. This mutation happens in a gene called PIG-A and the cells made by this stem cell lack certain proteins on their surface making them âweakerâ than normal blood cells.
Here are the steps that lead to PNH: 1  The abnormal stem cell makes copies of or clones itself. This leads to a whole population of stem cells that have mutant PIG-A. 2  The abnormal stem cells turn into mature red blood cells that have mutant PIG-A. These are called PNH red blood cells.