Could this be early symptom of ALS? (keep in mind it's familial)

I have a ? regarding the symptoms of a 75 year old male.  For about a month he's been complaining about an intermittent sharp pain in the buttock/back of thigh, which he says is eased by rest but gets numb after sitting awhile so he has to get up and walk around again. General dr said it sounded like sciatica, but the neurologist he saw last week never even mentioned the word.  He did say that his reflexes were "not appropriate" (whatever that means).  He's going for MRI, and physical therapy is also recommended.  He hasn't mentioned any weakness or twitching, just pain. He gets around pretty good, he's active always out going somewhere. He was recently in the hospital with chest pains. Don't know if that has anything to do with anything but they didn't find a problem, just kept him for observation.  

With anyone else I wouldn't think anything of it, but in this family ALS is familial, so he already has a 50% chance of having inherited the gene (from his father).  He has also had circulatory problems in the legs, and has had 2 surgeries over the years to improve this.

I've that people with familial ALS are "typically" younger at onset, whereas sporadic cases are "typically" middle-age to older (although his sister recently died of it at 72).  I also read that ALS symptoms started in the farthest extremeties and worked its way in (starting in the hands and/or feet, not the thighs).  It is also said that ALS doesn't involve pain or numbness, but firsthand accounts in reading forums have said otherwise.

I would like to hear your thoughts.  Thank you.

[CCF-Neuro-M.D.-PW]

Its not clear to me what members of his family have ALS, you mention his sister had it, but this alone would not qualify it as familial. To be familial a clear family inheritance pattern must be demonstrated over at least one generation, or else a demonstration of the genetic defect (which is not readily available at this time)

While familial ALS is 'dominantly' inherited, not all dominant genes get transmitted in the direct fashion to give the 50% figure, this is known as 'reduced penetrance'

In any case it would be highly unusual to present at such a late age, especially if familial. Pain in the buttock would also not suggest ALS, but may be suggestive of a localized soft tissue problem, peripheral vascular disease, sciatica or lumbar stensosis. A pinched nerve can cause an abnormal reflex in the leg. ALS is a motor system problem, although for reasons we dont understand some patients do have sensory symptoms, but this is rare.

[laurajh]

I forgot to mention that he HAS had sciatica before, which cleared up on its own.  
Also, his circulatory problems are thought to be possibly damage from radiation exposure from bomb testing during the Korean war.

[laurajh]

It started with his father as far as we know.  Out of 7 of his children, 3 have inherited the disorder.  One sister is the 72 year old I mentioned, another sister died of it in her 40's, and the other sister is currently not sick but we know she's a carrier because 2 of HER sons are both afflicted in their 40's.  She's currently ok (knock wood) but it's probably only a matter of time :(  

The sister that recently died at 72 began her symtoms (symptoms) at 71 - she went fast.  It comforted me a bit when you said it's rare for familial onset symptoms to start this late, but then again she was 71 when it hit.  I'm just so concerned because this is my husband's family, and if his father is ok chances are he'll be ok too.

So far that's a total of 6 people (the dad was the 1st generation, 3 daughters of his for the 2nd generation, and 2 males of the 3rd generation).  They say ALS strikes 1 or 2 out of every 100,000.  Why can't we have these odds with the lottery?