Snapshot A fair skinned, blue eyes, mentallly retarded 5 year-old child is brought to the ER. He has a medical history showing failure to thrive and developmental delay. According to the mother the child developed a seizure disorder after he had a thrombolic episode involving the brain Introduction Results from abnormalities in the cysteine metabolism ETiology Genetics The most classic form is autosomal recessive incidence of 1/200,000 heterozygote carriers are symptomatic but to a lesser degree than homozygous Presentation Infants are normal at birth but soon show developmental delay failure to thrive Symptoms mimic Marfan's Syndrome fair skin blue eyes lens dislocation (downward) arachnodactyly thin bones premature atherosclerosis with associated MIs and strokes glaucoma cataracts mental retardation seizures (20%) studies Serum blood testing demonstrating increased levels of methionine and homocysteine Genetic testing can be performed but is much more costly Treatment Some patients respond to treatment with vitamin B6 complications Thromboembolic events are more common in homocysteinuria than in the common population