When is genetic testing indicated?

[karendaks]

I am a spontaneous case of XLH. I gave birth to two sons, now adults. My youngest son inherited the condition from me.   My question is regarding my oldest son.  He  has never had any symptoms of XLH, his labs from the time he was born have always been normal. He will be planning a family in the near future. Is there any reason why he should have testing? Thanks in advance for any insight you can provide.

[GinJones]

A genetics counselor spoke at last year's XLH Day, and her presentation was taped, so you can see it at youtube:

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You might suggest to your son that he consult a genetics counselor, just for his peace of mind. I believe the speaker in that video gives a website where you can locate accredited counselors.

Personally, and this is just me speaking, and I'm not a doctor, just a layperson, but it seems HIGHLY unlikely that your son could transmit the mutation that causes XLH. Technically, he couldn't pass along the X-linked version of hypophosphatemia, because it's a dominant condition, so if he had the mutation in his genes, he would also have the condition and, at a minimum, low phos in the blood. He also couldn't pass along the ADHR (Autosomal Dominant Hypophosphatemic Rickets) version, because it, too, is dominant.

There have, I believe been a vanishingly few number of reported cases of a recessive version, but the odds against having that are astronomical.

[karendaks]

Gin, thanks so much for your thoughtful reply. It was very helpful;particularly the ADHR explanation, though I have heard of it, didn't know anything about it or how it could be inherited.  Was worried that perhaps I was missing some information, and that this son could have it but not present with any of the XLH issues. Since he has normal labs, height 6'2" and none of the XLH symptoms, my mind is now at ease.