alzheimers disease is not just a random occurrence it results from a mutated gene heres how it works creditnick cote for the new york timesmarch 7 2016marty and matt reiswig two brothers in denver knew that alzheimers disease ran in their family but neither of them understood why then a cousin gary reiswig whom they barely knew wrote a book about their family the thousand mile starewhen the brothers read it they realized what they were facingin the extended reiswig family alzheimers disease is not just a random occurrence it results from a mutated gene that is passed down from parent to childif you inherit the mutated gene alzheimers will emerge at around age 50 with absolute certainty your child has a 5050 chance of suffering the same fatethe revelation came as a shock and so did the next one the brothers learned that there is a blood test that can reveal whether one carries the mutated gene they could decide to know if they had it or notits a dilemma more people are facing as scientists discover more genetic mutations linked to diseases often the newly discovered gene increases risk but does not guarantee itsometimes knowing can be useful if you have a gene mutation that makes colon cancer much more likely for example then frequent colonoscopies may help doctors stave off troublebut then there are genes that make a dreaded disease a certainty there is no way to prevent it and no way to treat itmarty reiswig 37 saw his father now in the final stages of alzheimers slowly lose his ability to think to remember to care for himself or even to recognize his wife and sonsmr reiswig knows that if he has the gene he has perhaps a bit more than a decade before the first symptoms appear if he has it his two young children may have it toohe wavers about getting testedsometimes i think this is a terrible storm on the horizon that could absolutely devastate us and i want to know if it is real or not other times i say gosh if i do find out that it is real and i know i will die that way and i know probably the age i will die that is an almost unbearable amount of information about my futurepeople say you could go sky diving or ride a bull but you can only do things like that as long as time and income provide you still have to get up in the morning and go to work and pay your billshe joined a study at the washington university school of medicine in st louis in which researchers are following members of families with the genes for earlyonset alzheimers disease at a recent meeting he recalled he found himself in a room full of people like himself all had a parent with an alzheimers geneall were at risk of having the mutated gene themselvesmr reiswig asked the group how many have been testedhalf