PMR in the same family

My brother-in-law developed PMR about 12 years ago.

I developed PMR about 2 years ago, and GCA one year ago. I see my brother-in-law several times a year, but we live in different cities about 200 miles apart.

Yes! There is very little on this topic! My husband has had PMR and GCA for two years. I was just diagnosed with PMR. Very weird.

Welcome @boomerlib, Here's some recent research information I found on the topic.

"The interplay between genetic and environmental factors, including possible epigenetic effects, highlights the complex immune pathophysiology of PMR and GCA. While some progress has been made in identifying triggers, many mechanisms remain unclear. Further research is necessary to elucidate causative pathways and early steps potentially informing preventive strategies."
-- Environmental factors in polymyalgia rheumatica and giant cell arteritis:
https://www.researchgate.net/profile/Elvis-Hysa/publication/389375590_Environmental_factors_in_polymyalgia_rheumatica_and_giant_cell_arteritis/links/67c40d4e8311ce680c793c0d/Environmental-factors-in-polymyalgia-rheumatica-and-giant-cell-arteritis.pdf
Since you mentioned you were just diagnosed with PMR, you might want to scan through other discussions in the PMR Support Group - https://connect.mayoclinic.org/group/polymyalgia-rheumatica-pmr/

According to the studies in the link, quite a few possibilities for causes of PMR and GCA have been explored. There's a fair bit of evidence for a genetic predisposition related to Scandinavian or Northern European ancestry. My father had GCA and PMR and I have both as well. My father's mother was of Scottish descent and my DNA test shows 7% Scottish, 5% Norwegian , the rest English and German. Women are 2-3 times as likely as men to get these diseases. My father had 3 brothers and I am the only woman in the next generation to live to greater than 70 years old, when PMR tends to occur. My father must have had a good dose of PMR genes and passed them to me! However, this doesn't explain why a husband and wife or in-laws would both get the disease.

My maternal aunt had GCA. My mother's family was primarily southern Italian descent. My mother in law had GCA. She was British descent with some French. My genetic background is primarily Italian with Greek and some English, no Scandanavian.
I read that the highest rates of GCA/PMR in the US are in Minnesota, and in Europe, primarily Scandanavia and Northern Europe.
The earliest documentation of GCA was in the 10th century Baghdad (source: Perplexity.ai)

I came down with PMR at 68 during a stressful physical period in my life (and we were building a house). I believe my mother and her mother came down with it during very stressful mental periods in their lives. They called it bursitis. My grandmother was in her 40s and did not have access to prednisone, suffered the rest of her life, and developed partial blindness. My mother was in her 60s and must have gotten hold of prednisone because she made a remarkable recovery and never suffered from it again. I also took prednisone which removed my symptoms. All of us of northern European descent.

This is a very interesting discussion. I had not been aware of any PMR in my family prior to my diagnosis but my cousin was diagnosed at approximately the same time and we have both had hip, shoulder, and hand pain. She is older than I am but our severity has been about the same. My DNA revealed 6 % Norwegian heritage and the rest of my DNA is primarily African and Caribbean. I remain intrigued about potential links to PMR and look forward to remission! ❤️

My brother had PMR seven years ago and is fully recovered. Now I have it. We are of European descent. There definitely appears to be genetic predispositions to this disease.