Elevated total plasma homocysteine (hyperhomocysteinemia) is a marker of cardiovascular, thrombotic, and neuropsychological disease. It has multiple causes, including the common nutritional vitamin B12 or folate deficiency. However, some rare but treatable, inborn errors of metabolism (IEM) characterized by hyperhomocysteinemia can be missed due to variable presentations and the lack of awareness. The aim of this study is to identify undiagnosed IEM in adults with significantly elevated homocysteine using key existing clinical data points, then IEM specific treatment can be offered to improve outcome. We conducted a retrospective study with data mining and chart review of patients with plasma total homocysteine >30 μmol/L over a two-year period. We offer biochemical and genetic testing to patients with significant hyperhomocysteinemia without a clear explanation to diagnose IEM. We identified 22 subjects with significant hyperhomocysteinemia but no clear explanation. Subsequently, we offered genetic testing to seven patients and diagnosed one patient with classic homocystinuria due to cystathionine beta-synthase deficiency. With treatment, she lowered her plasma homocysteine and improved her health. This study stresses the importance of a thorough investigation of hyperhomocysteinemia in adults to identify rare but treatable IEM. We propose a metabolic evaluation algorithm for elevated homocysteine levels.

An 11-year-old boy with marfanoid habitus and high myopia presented with multiple episodes of seizures. He was found to have arachnodactyly, hypermobile joints, ectopia lentis, cerebral venous sinus thrombosis (CVST) with very high serum methionine and homocysteine. Genetic evaluation unveiled homocystinuria due to cystathionine beta-synthase deficiency. The patient was treated with high-dose pyridoxine, methionine restricted diet, anticonvulsants, warfarin, and correction of ectopia lentis. Homocystinuria should be suspected in patients with tall stature and pathological myopia. Early treatment can prevent thromboembolic complications.

We present the results of the 45-year clinical observation of 27 Russian homocystinuria patients. We made a mutation analysis of the CBS gene for thirteen patients from eleven unrelated genealogies. All patients except for the two were compound heterozygotes for the mutations detected. The most frequent mutation in the cohort investigated was splice mutation IVS11-2a->c. We detected one new nonsense mutation, one new missense-mutation and three novel small deletions. We also report the clinical case of the B6-responsive patient genotyped as Ile278Thr/Cys109Arg.

Homocystinuria due to cystathionine-β-synthase deficiency (CBS deficiency) usually presents with ectopia lentis, myopia, intellectual disability, skeletal anomalies resembling Marfan syndrome, and thromboembolic events. Whereas neurodevelopment impairments have been often described in untreated homocystinuria adult patients, acute psychosis has rarely been reported as a presenting symptom of the disease. Here, we describe a 17-year-old girl affected by CBS deficiency presenting acute onset of visual hallucinations, behavioral perseverance, psychomotor hyperactivity, and affective inappropriateness. Ectopia lentis, diagnosed several years before, didn't have been considered as possible sign of a metabolic disorder. Psychotic symptoms were unresponsive to the conventional antipsychotic drugs and relieved after pyridoxine and folic acid treatment. A diagnosis of homocystinuria due to CBS deficiency should be considered in patients presenting, as target signs, ectopia lentis with or without learning difficulties, and should also be taken into account as a potentially treatable cause of acute psychosis in childhood and adolescence. • Homocystinuria frequently present with ectopia lentis, myopia, cognitive impairment, Marfan-like phenotype, osteoporosis, cerebrovascular, or cardiac thrombosis. • Acute psychosis has rarely been reported as a presenting symptom of the disease. • The complete psychotic symptoms' remission with pharmacological doses of pyridoxine and folic acid, without antipsychotic drugs.

Homocystinuria is a rare inherited disorder due to a deficiency in cystathionine beta synthase. Individuals with this condition appear normal at birth but develop serious complications in childhood. Diagnosis and treatment started sufficiently early in life can effectively prevent or reduce the severity of these complications. This is an update of a previously published review. To determine if newborn population screening for the diagnosis of homocystinuria due to cystathionine beta synthase deficiency leads to clinical benefit compared to later clinical diagnosis. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Inborn Errors of Metabolism Trials Register.Date of the most recent search of the Inborn Errors of Metabolism Register: 08 June 2015. Randomised controlled trials and controlled clinical trials assessing the use of any neonatal screening test to diagnose infants with homocystinuria before the condition becomes clinically evident. Eligible studies compare a screened population versus a non-screened population. No studies were identified for inclusion in the review. No studies were identified for inclusion in the review. We were unable to identify eligible studies for inclusion in this review and hence it is not possible to draw any conclusions based on controlled studies; however, we are aware of uncontrolled case-series which support the efficacy of newborn screening for homocystinuria and its early treatment. Any future randomised controlled trial would need to be both multicentre and long term in order to provide robust evidence for or against screening and to allow a cost effectiveness analysis to be undertaken.