Some degree of mental retardation is usually seen but some affected people have normal IQs. When mental retardation is present, it is generally progressive. Affected people commonly develop blood clots . Thromboembolic episodes can cause damage in any tissue the embolus lodges in. Emboli to the brain can produce severe sequela.
Genetic counseling is recommended for prospective parents with a family history of homocystinuria.
There may be a history of frequent thromboembolic episodes. A skeletal X-ray shows osteoporosis. A standard ophthalmic exam confirms myopia and dislocated lens. Affected children may also have cataracts , glaucoma , and retinal detachment . An amino acid screen shows elevated methionine and homocystine levels.