Over at the medical genetics forum on MedHelp, senior genetics counselor Lisa Kessler responds to an inquiry about the inheritance patterns of ALS (amyotrophic lateral sclerosis), which is also known as Lou Gehrig’s disease. Many people assume serious conditions such as ALS are either hereditary or they are not. We are increasingly finding, however, that for many conditions — ALS being one of them — it’s not black and white. ALS is particularly interesting in that in can be inherited in different ways. Here’s how Lisa explains it:
Lisa’s answer: Approximately 10% of amyotrophic lateral sclerosis (ALS) cases are familial. As you know, ALS is a neurodegenerative disorder in which motor neurons (nerve cells that communicate to muscle cells) in the brain, brainstem, and spinal cord die. This causes paralysis and death. ALS usually begins in middle adult life, and the lifetime risk of developing ALS is 1 in 800.
One gene, called SOD1, causes 20% of familial ALS, and molecular testing for this gene is available on a clinical basis. ALS associated with the SOD1 gene is inherited in an autosomal dominant way, which means that someone with the condition has a 50% chance of passing it on. However, not everyone with the gene mutation develops the condition. ALS can also be inherited in autosomal recessive or an X-linked dominant way and can be due to other factors.
It may help you and your family to meet with a genetic counselor and review your paternal family history in detail and discuss if the testing is appropriate. As you know, you can find a genetic counselor through the NSGC’s website.
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