homocystinuria is a hereditary disease caused by a defect in the enzymes involved in metabolizing methionine . homocystinuria can influence many systems and may be mistaken for other diseases , including moyamoya disease . here , we report the case of a 10-year - old male patient with a diagnosis of moyamoya disease who had been monitored for that for an extended period . the patient s diagnosis was changed to homocystinuria as a result of lens subluxation and cataract findings . a 10-year - old male patient presented with vomiting , headache , lethargy , muscular weakness , and eye redness . the patient was mentally retarded , his right pupil was hyperemic , and he had muscle weakness on his left side . a neck and cranial computed tomography ( ct ) angiography showed no flow bilaterally past the bifurcation of the carotid artery . the patient s bilateral internal carotid arteries were determined to be occluded . it was considered that his eye findings could be compatible with a metabolic disease . on metabolic screening , the patient s homocysteine level was very high . in addition , his treatment regimen included vitamins b12 and b6 . with these treatments , in cases of unusual vascular lesions , metabolic diseases must be considered . in homocystinuria , blood homocysteine levels can be returned to normal , and some complications can be prevented . it is characterized by mental retardation , an atypical facial appearance , lens dislocation , skeletal anomalies , osteoporosis , and thrombosis ( 1 ) . the second is trans - sulfuration to cysteine , using vitamin b6 as a cofactor . these reactions reduce the total homocysteine concentrations in the cells and blood ( 2 ) . hyperhomocysteinuria is caused by deficiencies in methylene tetrahydrofolate reductase ( mthfr ) , cystathionine beta synthase , or enzymes involved in homocysteine methylation and methyl - b12 synthesis ( 1 ) . arterial and venous thrombosis and arteriosclerosis may be seen in patients with homocysteinemia ( 2 ) . although the mechanism of damage due to homocysteine is not entirely clear , it is believed that disturbances in methylation reactions ultimately lead to vascular obstruction ( 3 ) . cerebral infarcts or strokes among children are rare , but they can cause significant morbidity and mortality ( 4 ) . moyamoya disease can also present with progressive stenosis or occlusion of the intracranial internal carotid artery . the clinical presentation and imaging findings may be similar to those of homocystinuria ( 5 ) . in homocystinuria it has been suggested that early detection and treatment are helpful and that homocysteine levels can be controlled with vitamins b6 and b12 , which are cofactors needed for homocysteine metabolism , and with folic acid supplements ( 2 ) . this article presents the case of a patient who had been diagnosed with moyamoya disease and followed for an extended period . the patient s ocular findings were compatible with homocystinuria ; thus , he was evaluated for metabolic disease and ultimately diagnosed as having homocystinuria . after beginning an appropriate diet and treatment regimen consisting of folate and vitamin b12 , the patient s clinical findings regressed moderately . 2015 - 378 ) . in june 2014 , a 10-year - old male patient presented to the pediatric outpatient clinic of bagcilar training and research hospital ( istanbul , turkey ) with vomiting , headache , lethargy , eye redness , and a speech disorder . on physical examination , the patient s body temperature was 37.3c and his blood pressure was 189/110 mmhg ( 95th percentile , 125/80 mmhg ) . he had muscular weakness on the left side and a dilated , hyperemic right pupil . an examination of mental state at admission showed poor socialization , isolation , learning difficulties , and mild mental retardation . given these findings , the patient was hospitalized . the patient and his family had moved to istanbul from another city . we learned that he had been hospitalized due to an intracranial pathology and had had surgery on his left eye when he was 5 years old , but no medical records of this could be obtained . the patient had long suffered from learning difficulties , and he had been followed at another hospital as a case of moyamoya disease . following his admission to the pediatric clinic , antihypertensive treatment was initiated . however , on cranial ct angiography , no flow was seen bilaterally in the anterior cerebral artery ( aca ) . the bilateral middle cerebral artery ( mca ) and aca territories were vascularized by a thick , right - posterior communicating artery ( figure 1 ) . doppler ultrasound tests of the renal artery were normal , and no renal artery stenosis was found . the patient s complete blood cell count , biochemical test results , thyroid function , and serum levels of renin , aldosterone , cortisol , and cholesterol were normal . in addition , the patient s protein c , protein s , antithrombin iii , and factor 5 leiden levels were normal . an ophthalmologist reported that these specific ocular findings were compatible with a metabolic disease , especially homocystinuria . mol / l ( normal level , 4.7 - 10.3 mol / l ) , his vitamin b12 level was 108 pg / ml , and his folic acid level was 6.26 ng / ml . after 5 days of vitamin b12 treatment , the patient s vitamin b12 level was > 2000 pg / ml and his serum homocysteine level continued to be as high as 398 mol / l . therefore , the patient was referred to a specialist in pediatric endocrinology and metabolic diseases . the patient was prescribed a diet free from homocysteine and methionine and a treatment regimen consisting of betaine and vitamins b12 and b6 . each day , he was administered 400 mg of vitamin b6 and 15 mg of folic acid . during this period , the patient s blood pressure values were high and antihypertensive treatment continued . after 15 days , the patient s homocysteine level regressed to 23.4 mol / l and his blood pressure was under control . then , the patient underwent surgery at the eye clinic for lens subluxation and glaucoma . after the surgery , the acetyl salicylic acid treatment was terminated . at the one - year follow - up examination , the most characteristic and earliest symptoms of homocystinuria are subluxation of the lens and progressive myopia . mental retardation , cognitive impairment , a marfan - like phenotype , osteoporosis , and cerebrovascular and cardiac thrombosis are other presenting symptoms ( 7 ) . the wide range of both symptoms and severity can make diagnosis a challenge for even the most experienced clinician . as each particular manifestation of the disease should be evaluated in a different specialized clinical setting , it can be difficult to gather all of the relevant information to make an informed diagnosis ( 8) . because of the potential for serious complications , including increased tendency toward stroke , ocular complications , and mental impairment , early diagnosis and regular medical follow - ups are essential ( 9 ) . the patient had undergone surgery on his left eye when he was 5 years old , probably because of lens subluxation and glaucoma . since the patient s ocular findings were not evaluated properly , his diagnosis was delayed . during the same period , moyamoya disease is a rare disorder of the connective tissue of unknown origin that causes cerebrovascular occlusive disease . the main symptoms of moyamoya disease are bilateral steno - occlusive changes at and around the internal carotid artery bifurcation , along with abnormal net - like vessels , called moyamoya , in the basal ganglia ( 11 ) . neurological deficits in children with moyamoya disease can present as dysarthria , aphasia , hemiparesis , paraparesis , or visual symptoms . the clinical symptoms of homocystinuria include subluxation of the lens , which is also a characteristic feature of connective - tissue disorders ( 2 ) . however , the eye findings , including lens subluxation , a secondary cataract , and poor vision , discovered during this patient s eye examination pointed to a metabolic disease . in addition , in agreement with previously published cases of homocystinuria , the patient had a marfan - like phenotype , mental retardation , and cerebrovascular thrombosis with carotid - artery occlusion at the bifurcation level on ct angiography . mol / l ; 16 - 30 mol / l is moderate , 31 - 100 mol / l is intermediate , and a level above 100 mol / l indicates severe homocysteinemia ( 7 , 12 , 13 ) . thus , the patient s homocysteine level , 282 mol / l , was considered extremely high . in addition , he had severe hypertension at admission . hyperhomocysteinemia can lead to various complications . severe hyperhomocysteinemia causes thrombosis of systemic arteries and arterial endothelial dysfunction ( 14 , 15 ) . the literature contains no cases of systemic hypertension associated with hyperhomocysteinemia . however , one case had pulmonary hypertension that complicated homocystinuria ( 15 ) . mthfr plays an important role in the folate cycle and contributes to the metabolism of homocysteine ( 1 , 3 ) . the mthfr gene has at least two functional polymorphisms , 677 c > t and 1298 a > c. the mthfr 677 t allele is associated with reduced enzymatic activity , decreased levels of folate in serum , and increased plasma homocysteine levels ( 1 ) . in addition , mthfr 1298 a > c has decreased enzymatic activity , but it has been reported that this does not elevate plasma homocysteine concentrations ( 16 ) . although the patient s genetic analysis showed a heterozygous a1298c mutation , his homocysteine level was extremely high . the literature reports two cases with behavioral disorders and psychotic symptoms ( 2 , 7 , 8) . evidence indicates that appropriate treatment of homocystinuria markedly reduces the risk of vascular complications , even if biochemical control is suboptimal ( 17 ) . in most cases , vitamin supplementation results in near - normalization of plasma homocysteine . homocysteine metabolism requires the participation of folate as well as vitamins b12 ( cobalamin ) and b6 ( pyridoxal phosphate ) as coenzymes ; in addition , a diet low in methionine is important . betaine is a methyl donor ; it has the effect of converting homocysteine to methionine , and it can be used as a supplementary treatment . antiplatelet treatment must be applied to all patients with homocystinuria who have a history of cerebral infarction ( 3 ) . an appropriate diet and treatment with folate and vitamins b12 and b6 can prevent serious complications . in cases of unusual vascular lesions , in addition , homocystinuria must be considered in addition to moyamoya disease in cases with bilateral carotid occlusion , which may be observed in childhood . slow stroke phases , with continued progressive stenosis and eventual occlusion , are important in homocystinuria , and it must be remembered that it may affect many systems . as each particular manifestation of the disease should be evaluated in a different specialized setting , it can be difficult to gather all the relevant information to make an informed diagnosis . early diagnosis is important , and many complications can be prevented or reduced with an appropriate diet and treatment regimen . in cases of unusual vascular lesions , metabolic diseases must be kept in mind . in addition , homocystinuria must be considered in addition to moyamoya disease in cases with bilateral carotid occlusion , which may be observed in childhood . slow stroke phases , with continued progressive stenosis and eventual occlusion , are important in homocystinuria , and it must be remembered that it may affect many systems . as each particular manifestation of the disease should be evaluated in a different specialized setting , it can be difficult to gather all the relevant information to make an informed diagnosis . early diagnosis is important , and many complications can be prevented or reduced with an appropriate diet and treatment regimen .
introductionhomocystinuria is a hereditary disease caused by a defect in the enzymes involved in metabolizing methionine . 
 homocystinuria can influence many systems and may be mistaken for other diseases , including moyamoya disease . here , we report the case of a 10-year - old male patient with a diagnosis of moyamoya disease who had been monitored for that for an extended period . 
 the patient s diagnosis was changed to homocystinuria as a result of lens subluxation and cataract findings.case presentationa 10-year - old male patient presented with vomiting , headache , lethargy , muscular weakness , and eye redness . 
 the patient was mentally retarded , his right pupil was hyperemic , and he had muscle weakness on his left side . 
 in addition , his blood pressure was high . 
 the patient s history included a diagnosis of moyamoya . 
 a neck and cranial computed tomography ( ct ) angiography showed no flow bilaterally past the bifurcation of the carotid artery . 
 the patient s bilateral internal carotid arteries were determined to be occluded . it was considered that his eye findings could be compatible with a metabolic disease . on metabolic screening , the patient s homocysteine level was very high . 
 in addition , a heterozygous a1298c mutation was identified in mthfr . 
 therefore , the patient was started on a diet free from homocysteine and methionine . 
 in addition , his treatment regimen included vitamins b12 and b6 . with these treatments , the patient s complications 
 regressed.conclusionsin cases of unusual vascular lesions , metabolic diseases must be considered . in homocystinuria , 
 early diagnosis and treatment are important . 
 blood homocysteine levels can be returned to normal , and some complications can be prevented .