How Did I Get This Mutation? And Why Didn’t I Know Before?

A Lesson in Genealogy and Family History

Since a BRCA mutation ultimately comes down to genetics, this blog entry will explore how I came to inherit this mutation, and why I didn’t know about it until now.

I inherited the mutation from my father.  Dad has never had cancer.  Dad has 2 brothers.  Neither has/had a history of male breast cancer (one had pancreatic cancer).  I have 8 first cousins through these 2 brothers.  No cancer.  Dad has 7 first cousins on his maternal side.  No cancer.  And of course, neither of my siblings have cancer either.

Doesn’t sound very high risk, does it?  So where is the cancer?  How do I know it came from my dad?

One of my hobbies is family history.  I have done extensive research on where my ancestors came from.  I’ve spent vacations romping through cemeteries taking pictures of headstones, and hours on genealogy websites such as ancestry.com, and searching through obituaries and newspaper articles.  My family tree has about 1200 names on it, going back to the mid-1800s. 

My paternal grandmother, Anna, passed from ovarian cancer back in 1982.  She was 75.   Forty years ago, when someone in their 70s died of cancer, it didn’t raise any eyebrows.  It happened all the time. 

Here’s where things get interesting.  Anna had 2 younger sisters.  The youngest, Elsie, died in 1944 at the age of 31, leaving behind a husband and 2 sons, ages 12 and 6.  She died of breast cancer.  But let’s see—some relative who died decades before I was born, when my dad was a young teen (he was about 14 at the time of his aunt’s death), doesn’t exactly stay on the family radar.  In fact, Elsie’s husband eventually remarried and moved to California with the boys.  I have had minimal contact with Elsie’s children and grandchildren.  However, I learned through reading obituaries that the older of those 2 boys died of pancreatic cancer in 1994.

Anna had another sister, Clara (who I clearly resemble!).  Clara died in 1961 at the age of 49 as a result of—you guessed it—breast cancer.  Clara wasn’t as much of an unknown in the family as Elsie was, as her family remained on the east coast.  Clara left behind a husband and 3 children—a daughter and 2 sons.  All three of Clara’s children are still living, and I am close with several of Clara’s grandchildren (my second cousins).  Shout out to my Chaya sisters!

Anna had 2 biological sons.  Elsie had 2 sons.  Clara had 2 sons and a daughter.  Do you see the problem?  It has become clear that both Anna and Clara had the BRCA1 mutation; and Elsie almost certainly did as well (and probably passed it on to her oldest son).  The mutation was carried—and passed on—by all males.  While men can inherit and pass on a BRCA mutation, and BRCA1 does put men at a higher risk of male breast, pancreatic, and prostate cancer, the overall risk of a man being diagnosed with a BRCA-related cancer is still low. Yet it is now clear that many of them have the mutation. How do we know this?  Because 3 of my cousins have a confirmed BRCA1 mutation.  And we all have the same one.  We all got it from our fathers.