Maybe a reason why we don't have girls

At the age of 18 months my husband had a hemolytic anemia crisis.   This was caused by a blood disorder that was diagnosed at that time:  hereditary spherocytosis.  To solve the problem, his spleen was removed.

As each of our boys were born we had them tested for spherocytosis.  Austin has a mild case; so we will watch him closely.  In fact, last June he seemed to be slowing down significantly so we were able to get in to see the hemolytic pediatrician in Saskatoon on his very last day of work before his retirement.  I liked this pediatrician because his own son has spherocytosis and so he is very knowledgeable about the disorder.

Lately my husband has been struggling with a compression fracture in his back.  Why does someone his age have an 80 year old man's disease?  So I looked it up on the internet.  The possibilities are a little scarey.  For now we'll just ignore those and do what we can to help him get comfortable and heal his 'broken' back.  I've also been checking out the long term effects of spherocytosis and splenectomys.  I haven't found anything that links spherocytosis to a compression fracture.

But I did find something interesting:

HS usually is transmitted as an autosomal dominant trait, and the identification of the disorder in multiple generations of affected families is the rule. Homozygosity for this dominantly transmitted HS gene has not been identified. This suggests that the homozygous state is incompatible with life. Twenty-five percent of all newly diagnosed patients do not demonstrate a dominant inheritance pattern. Parents of these patients do not have clinical or hematological abnormalities. New mutations have been implicated that may explain some of these sporadic cases. 

From what I can understand, homozygosity refers to the two X chromosomes in females.  So this suggests that a female with spherocytosis would not live.

Since we do not know anyone else in John's extended family with this blood disorder, it might just be a new mutation.

So when our boys have children, we definitely need to check for this blood disorder.  Maybe our grandsons might have it.  If we're lucky enough to have granddaughters I would expect that they won't have it.