Brittle bone disease is an inherited disorder of bone. The bones are weak due to deficiency of collagen.
There are various grades of this disease. If your nephew is 17 months, it doesn't seem to be of the lethal type. Yes, if the diagnosis is right, he would encounter several fractures hereafter. These kids also have poor and delayed dentition. If the diagnosis is right, you should consult an Orthopaedician.
The current option is to splint the developing fractures. Once he starts developing deformities of his limbs, its advisable to undergo surgery(rodding) of his limb bones to prevent further progression of his deformities. Also, Bisphosphonates (drugs that strengthen the weak bones) are of great help in decreasing the frequency of these fractures.
I would also recommend a modification of his play/workplace by use of soft floor carpets, appropriate handles in the bathroom, smooth edged furnitures, low level cot, avoidance of contact sports and advocate other means to reduce frequent falls.

There are 2 types of symptoms based on collagen in lobstein syndrome.

As your child is 17 months old type 2 is not applicable in his case.

If your child has 3-4 of these symptoms then you can consult your nearest doctor for further evaluation .There information is for briefing you and not for diagnosis.You need to consult doctor for actual diagnosis of condition of your son.

* Bones fracture easily
* Slight spinal curvature
* Loose joints
* Poor muscle tone
* Discoloration of the sclera (whites of the eyes), usually giving them a blue-gray color. The blue-gray color of the sclera is due to the underlying choroidal veins which show through. This is due to the sclera being thinner than normal because of the defective Type I collagen not forming correctly.
* Early loss of hearing in some children
* Slight protrusion of the eyes

Source:http://en.wikipedia.org/wiki/Osteogenesis_imperfecta

Breaking of bones can also be due to rickets of somewhat calcium deficiency.You should not take any decision reagrding him without consulting doctor.

Hope this helps,
thanks

dr jignesh