35, Male, 5’8, 140lbs

Non smoker non drinker no drugs 

Medications: nizatidine, rabeprazole, zetia, vit D 

Complaints of muscle pain, joint pain, ligament pain, chronic GI issues, bifid uvula, and various other health complaints led to connective tissue genetic testing. 

COLA1 was identified, and concerns of OI led to being sent for a bone density scan to be “overly cautious and rule out OI”.

In fact my geneticist was so confident that the scan would be normal they told me we could rule out any pathogenic meaning of the COLA1 gene once it came back normal. However it didn’t come back normal. It showed low bone density and osteopenia. The results were:

FINDINGS:  Right femoral neck: BMD 0.753 g/cm2, Z score -2.3  Total right hip: BMD 0.735 g/cm2, Z score -2.4  Left femoral neck: BMD 0.787 g/cm2, Z score -2.0  Total left hip: BMD 0.750 g/cm2, Z score -2.3  Lumbar spine (L1-L4): BMD 1.015 g/cm2, Z score -1.7  

FRAX: Not reported.  In men under the age of 50, a Z-score of > -2.0 is within the expected range for age, and a Z-score -2.0 and lower is defined as below the expected range for age.

My geneticist called me very confused and told me they were referring  me to an endocrinologist because they have no idea why my bone density is low. They said if I had OI it’s very unheard of that I haven’t had any fractures of long bones in my life time. 

My question is, what are the diseases or underlying causes that can cause these bone density scan results in a 35 year old male? I was told the wait for the endocrinologist could be 6+ months and I’m just curious in the mean time what could be causing it so I can be well informed when going to discuss.

Genetic testing led to bone density scan. Scan showed low bone density, increased fracture risk 35 year old male. What could be causing this?