Panelists suggest how to differentiate between diabetic neuropathy and ATTR amyloidosis.
John L. Berk, MD: Dr Dyck, are diabetic disease and ATTR [amyloidosis transthyretin] neuropathy exclusive or can they be combined, and how do you differentiate?
P. James B. Dyck, MD: He’s raised a very good point. In fact, I was going to take some issue with that. I don’t think we can just assume if you have a positive genetic test, then your neuropathy is due to hATTR [hereditary ATTR]. For example, I saw an African American gentleman who had a positive genetic test, who had been diabetic for 30 years, had some prickling in his toes, had a cardiomyopathy, and they were all ready to put him on either patisiran or inotersen, and they wanted me to start it. I looked at him, and his neuropathy was very minimal. He had background retinopathy, and he had background nephropathy. I did a nerve biopsy on him, and there was no amyloid. I determined his neuropathy was a diabetic polyneuropathy and not because of his hATTR. Now, his cardiologist and his hematologist may not have been thrilled with me, but I still think there is some intellectual honesty that we need to do.
A positive genetic test is not a diagnosis of hATTR. It confers a carrier state. The cardiologist and the neurologist have diverged in this respect, because a positive PYP [pyrophosphate] scan is taken as diagnostic evidence that you have an amyloid cardiomyopathy. From my perspective, you can have a neuropathy in a genetic test, but you still need to do some more work to establish that the 2 are related. I personally still prefer having a positive tissue diagnosis of amyloid for the neuropathy cases.
John L. Berk, MD: Thank you for watching this NeurologyLive® Peer Exchange. If you enjoyed the content, please subscribe to our e-newsletters to receive upcoming Peer Exchanges and other great content right in your in-box.
Transcript Edited for Clarity