Interplay of Enzyme Therapy and Dietary Management of Murine Homocystinuria.

Albeit effective, methionine/protein restriction in the management of classical homocystinuria (HCU) is suboptimal and hard to follow. To address unmet need, we developed an enzyme therapy (OT-58), which effectively corrected disease symptoms in various mouse models of HCU in the absence of methionine restriction. Here we evaluated short- and long-term efficacy of OT-58 on the background of current dietary management of HCU. Methionine restriction resulted in the lowering of total homocysteine (tHcy) by 38-63% directly proportional to a decreased methionine intake (50-12.5% of normal). Supplemental betaine resulted in additional lowering of tHcy. OT-58 successfully competed with betaine and normalized tHcy on the background of reduced methionine intake, while substantially lowering tHcy in mice on normal methionine intake. Betaine was less effective in lowering tHcy on the background of normal or increased methionine intake, while exacerbating hypermethioninemia. OT-58 markedly reduced both hyperhomocysteinemia and hypermethioninemia caused by the diets and betaine in HCU mice. Withdrawal of betaine did not affect improved metabolic balance, which was established and solely maintained by OT-58 during periods of fluctuating dietary methionine intake. Taken together, OT-58 may represent novel, highly effective enzyme therapy for HCU performing optimally in the presence or absence of dietary management of HCU.

Is the gut microbiota dysbiotic in patients with classical homocystinuria?

Classical homocystinuria (HCU) is characterized by increased plasma levels of total homocysteine (tHcy) and methionine (Met). Treatment may involve supplementation of B vitamins and essential amino acids, as well as restricted Met intake. Dysbiosis has been described in some inborn errors of metabolism, but has not been investigated in HCU. The aim of this study was to investigate the gut microbiota of HCU patients on treatment. Six unrelated HCU patients (males = 5, median age = 25.5 years) and six age-and-sex-matched healthy controls (males = 5, median age = 24.5 years) had their fecal microbiota characterized through partial 16S rRNA gene sequencing. Fecal pH, a 3-day dietary record, medical history, and current medications were recorded for both groups. All patients were nonresponsive to pyridoxine and were on a Met-restricted diet and presented with high tHcy. Oral supplementation of folate (n = 6) and pyridoxine (n = 5), oral intake of betaine (n = 4), and IM vitamin B12 supplementation (n = 4), were reported only in the HCU group. Patients had decreased daily intake of fat, cholesterol, vitamin D, and selenium compared to controls (p < 0.05). There was no difference in alpha and beta diversity between the groups. HCU patients had overrepresentation of the Eubacterium coprostanoligenes group and underrepresentation of the Alistipes, Family XIII UCG-001, and Parabacteroidetes genera. HCU patients and controls had similar gut microbiota diversity, despite differential abundance of some bacterial genera. Diet, betaine, vitamin B supplementation, and host genetics may contribute to these differences in microbial ecology.

Fórmula metabólica isenta de metionina para homocistinúria clássica / Methionine-free metabolic formula for classical homocystinuria

CONTEXTO: A homocistinúria clássica (HCU) é uma doença rara, do tipo erro inato do metabolismo, de herança autossômica recessiva, cujo defeito metabólico na enzima cistationina ß-sintase (CBS) leva ao acúmulo de metionina, homocisteína (responsável pelos fenômenos tromboembólicos associados) e seus derivados, com deficiência de cistationina e cisteína (responsável pelas alterações em tecido conjuntivo associadas, tais como subluxação de cristalino). A prevalência da HCU é estimada entre 1:200.000 a 1:300.000 recém-nascidos vivos, podendo chegar a 1:60.000 (1). No Brasil, existem pelo menos 80 pacientes diagnosticados, de acordo com a Sociedade de Pacientes representante da doença, e o subdiagnóstico ou diagnóstico mais tardio que a média dos outros países acaba sendo mais frequente, uma vez que a doença não está inserida no Programa Nacional de Triagem Neonatal (PNTN). Sem diagnóstico e tratamento precoces, o paciente com HCU manifesta clinicamente as condições que ocorrem devido ao acúmulo de homocisteína e metionina e consequente deficiência de cisteína, tais como subluxação de cristalino, escoliose, redução da densidade mineral óssea (DMO), tromboembolismo, acidentes vasculares cerebrais, retardo mental, manifestações psiquiátricas, entre outras. Como a piridoxina (vitamina B6) é um cofator da CBS, ela melhora a atividade da enzima nos casos responsivos e, desta forma, acarreta em um quadro menos grave de doença. Entretanto, nem todos os pacientes com HCU são responsivos à piridoxina. Para classificar o paciente de acordo com a responsividade à piridoxina, há a necessidade de realizar o teste de suplementação, que culmina por classificar a HCU em três formas: responsiva à piridoxina, não-responsiva à piridoxina e com resposta intermediária à piridoxina. O tratamento recomendado para pacientes responsivos é piridoxina 10 mg/Kg/dia, evitando-se dose acima de 500 mg/dia. O tratamento dietético (dieta restrita em metionina e suplementada com fórmula isenta em metionina - FMIM) deve ser utilizado em pacientes que não atingiram níveis ideais de homocisteína com a suplementação de piridoxina. TECNOLOGIA: Fórmula metabólica isenta de metionina. EVIDÊNCIAS CIENTÍFICAS: Por ser uma doença bastante rara, há pouca literatura disponível que avalie a condição de HCU. Desta forma, foram considerados quaisquer estudos em seres humanos, independente do delineamento. Não foram identificados Ensaios Clínicos Randomizados ou estudos clínicos com grupo controle (sem intervenção). Foram identificados apenas três estudos observacionais nesta revisão, sendo dois irlandeses (onde sabidamente a incidência é maior que em outros países) e um coreano. Em ambos os países, a triagem para HCU é realizada no período neonatal. Nos três estudos, parte dos pacientes avaliados foi diagnosticada em períodos posteriores ao neonatal e em dois deles os autores realizaram análises comparativas entre os grupos com diagnostico neonatal e com diagnóstico tardio para avaliação dos desfechos. Os desfechos de interesse avalidos pelos estudos foram: níveis plasmáticos de homocisteína (2 estudos), densidade mineral óssea (1 estudo), níveis plasmáticos de metionina (2 estudos), eventos tromboembólicos (2 estudos), subluxação do cristalino (1 estudo) e deficiência intelectual (1 estudo) (2-4). Desfechos de sobrevida, qualidade de vida e convulsão em pacientes com HCU não foram diretamente avaliados pelos estudos, embora a ocorrência de fenômenos tromboembólicos esteja associada à sobrevida (tais eventos são a principal causa de óbito de pacientes com HCU). Os estudos demostraram que a intervenção foi capaz de manter os níveis de homocisteína dentro dos níveis-alvo preconizado pelo tratamento (<100 mmol/L). Houve a manutenção da densidade mineral óssea durante o período de seguimento de 3,4 anos do estudo que avaliou esse desfecho. Para eventos troboembólicos, o estudo de Lim e Lee (2013) identificou uma ocorrência (1/5, 20%), mas Yap e Naughten (1998), que também o avaliou, não identificou caso (0/25, 0%). Yap e Naughten (1998) identificaram a ocorrência de seis eventos de subluxação de cristalino em pacientes que não foram aderentes ao tratamento ou que foram diagnosticados tardiamente, quando comparado a nenhum evento de subluxação de cristalino no grupo de pacientes que foram diagnosticas no período neonatal e aderentes à dieta e FMIM. Não houve relatos de eventos adversos à FMIM nos estudos. IMPACTO ORÇAMENTÁRIO: Foram avaliadas duas FMIM para HCU individualmente em todos os pacientes acima de um ano de idade não responsíveis à piridoxina (HCYSMED B PLUS e XMET MAXAMUM). Dois cenários de impacto orçamentário foram projetados na perpectiva do SUS e com horizonte temporal de 5 anos (2019-2023). No Cenário 1 foi assumida a população oriunda da incidência média de HCU em recém nascidos, sendo o impacto para HCYSMED B PLUS de aproximadamente R$ 43 milhões em 2019 e R$ 221 milhões após os cinco anos, ou, para XMET MAXAMUM, de aproximadamente R$ 36,6 milhões em 2019 e R$ 188 milhões após os cinco anos propostos após a incorporação. No Cenário 2 foi assumida a população estimada de subdiagnóstico no Brasil (17,6%) em relação ao número de pacientes registrados pela Associação Brasileira de Homocistinúria (80 em 2016), sendo o impacto para HCYSMED B PLUS de aproximadamente R$ 7,5 milhões em 2019 e R$ 38,9 milhões após os cinco anos, ou, para XMET MAXAMUM, de aproximadamente R$ 6,5 milhões em 2019 e R$ 33,1 milhões após os cinco anos. A principal limitação é a incerteza quanto à população elegível ao tratamento devido à falta de dados publicados no Brasil. A diferença da dieta recomendada entre pacientes também é uma variável que não foi explorada nessa avaliação, assim como os custos com outros medicamentos. RECOMENDAÇÃO PRELIMINAR: A CONITEC, em sua 67ª reunião ordinária, realizada no dia 14 de junho de 2018, recomendou a não incorporação no SUS da fórmula metabólica isenta de metionina para homocistinúria clássica. Foram considerados vários fatores como a dificuldade no diagnóstico, as fragilidades encontradas nas evidências disponíveis e a ausência de dados para os desfechos considerados clinicamente relevantes. CONSULTA PÚBLICA: A matéria esteve em consulta pública no período de 06 a 25 de julho de 2018 e obteve um total de 746 contribuições, sendo 10 pelo formulário de contribuições técnico-científicas e 736 pelo formulário de contribuições sobre experiência ou opinião. Entre as 736 contribuições sobre experiência ou opinião, 722 eram discordantes (715 totalmente e 7 parcialmente) em relação à recomendação preliminar, e a grande maioria foi de familiares, amigos ou cuidadores do paciente (554). Todas as contribuições técnico-científicas discordaram da recomendação da CONITEC (9 totalmente e 1 parcialmente) e foram em sua maioria de profissionais da saúde (6). A empresa fabricante contribuiu sobre o impacto orçamentário. Outra contribuição sobre a análise econômica apresentada no parecer alegou que a análise foi simplista. Após apreciação das contribuições encaminhadas pela Consulta Pública, a CONITEC entendeu que as evidências disponíveis sobre a utilização da FMIM apontam benefícios na redução de eventos tromboembólicos e, consequentemente, na sobrevida de pacientes com HCU, mesmo quando diagnosticados tardiamente. Além disso, sugere-se a avaliação da inclusão da Triagem Neonatal Expandida (por "tandem") no SUS para o diagnóstico precoce da HCU e de outras doenças metabólicas. RECOMENDAÇÃO FINAL: Os membros da CONITEC presentes na 76ª reunião ordinária, no dia 04 de abril de 2019, deliberaram por unanimidade recomendar a incorporação no SUS da fórmula metabólica isenta de metionina para homocistinúria clássica, conforme Protocolo Clínico e Diretrizes Terapêuticas. Foi assinado o Registro de Deliberação nº 437/2019. DECISÃO: Incorporar a fórmula metabólica isenta de metionina para homocistinúria clássica, conforme Protocolo Clínico e Diretrizes Terapêuticas do Ministério da saúde, no âmbito do Sistema Único de Saúde - SUS. Dada pela Portaria nº 32, publicada no Diário Oficial da União nº 141, seção 1, página 89, em 24 de julho de 2019.

Classical Homocystinuria in a Juvenile Patient.

Classical homocystinuria, also known as cystathionine beta synthase deficiency, is a rare disorder of methionine metabolism, leading to an abnormal accumulation of homocysteine and its metabolites in blood and urine. A young child with homocystinuria is discussed, who presented with behavioral abnormalities, involuntary movement, mental retardation, and decreased vision since birth. The diagnosis of homocystinuria was not made at initial presentation. Subtle phenotypic features with developmental delay and MRI brain finding of bilateral medially dislocated lens, eventually provided the first indication at five years of age. Laboratory screening with plasma amino acid profile by ion exchange chromatography (IEC) showed elevated homocystine and methionine, and low cystine in plasma in the absence of vitamin B12, and folate deficiency; giving the diagnosis of classical homocysteinuria.

Effects of medical food leucine content in the management of methylmalonic and propionic acidemias.

PURPOSE OF REVIEW: The current review highlights the varied effects of medical foods high in leucine (Leu) and devoid of valine (Val) and isoleucine (Ile) in the management of methylmalonic acidemia (MMA) and propionic acidemia and cobalamin C (cblC) deficiency, aiming to advance dietary practices. RECENT FINDINGS: Leu is a key metabolic regulator with a multitude of effects on different organ systems. Recent observational studies have demonstrated that these effects can have unintended consequences in patients with MMA as a result of liberal use of medical foods. The combination of protein restriction and medical food use in MMA and propionic acidemia results in an imbalanced branched-chain amino acid (BCAA) dietary content with a high Leu-to-Val and/or Ile ratio. This leads to decreased plasma levels of Val and Ile and predicts impaired brain uptake of multiple essential amino acids. Decreased transport of methionine (Met) across the blood-brain barrier due to high circulating Leu levels is of particular concern in cblC deficiency in which endogenous Met synthesis is impaired. SUMMARY: Investigations into the optimal composition of medical foods for MMA and propionic acidemia, and potential scenarios in which Leu supplementation may be beneficial are needed. Until then, MMA/propionic acidemia medical foods should be used judiciously in the dietary management of these patients and avoided altogether in cblC deficiency.

Guidelines for the diagnosis and management of cystathionine beta-synthase deficiency.

Cystathionine beta-synthase (CBS) deficiency is a rare inherited disorder in the methionine catabolic pathway, in which the impaired synthesis of cystathionine leads to accumulation of homocysteine. Patients can present to many different specialists and diagnosis is often delayed. Severely affected patients usually present in childhood with ectopia lentis, learning difficulties and skeletal abnormalities. These patients generally require treatment with a low-methionine diet and/or betaine. In contrast, mildly affected patients are likely to present as adults with thromboembolism and to respond to treatment with pyridoxine. In this article, we present recommendations for the diagnosis and management of CBS deficiency, based on a systematic review of the literature. Unfortunately, the quality of the evidence is poor, as it often is for rare diseases. We strongly recommend measuring the plasma total homocysteine concentrations in any patient whose clinical features suggest the diagnosis. Our recommendations may help to standardise testing for pyridoxine responsiveness. Current evidence suggests that patients are unlikely to develop complications if the plasma total homocysteine concentration is maintained below 120 µmol/L. Nevertheless, we recommend keeping the concentration below 100 µmol/L because levels fluctuate and the complications associated with high levels are so serious.

The effect of dietary modulation of sulfur amino acids on cystathionine ß synthase-deficient mice.

Cystathionine ß synthase (CBS) is a key enzyme in the methionine and cysteine metabolic pathway, acting as a metabolic gatekeeper to regulate the flow of fixed sulfur from methionine to cysteine. Mutations in the CBS gene cause clinical CBS deficiency, a disease characterized by elevated plasma total homocysteine (tHcy) and methionine and decreased plasma cysteine. The treatment goal for CBS-deficient patients is to normalize the metabolic values of these three metabolites using a combination of vitamin therapy and dietary manipulation. To better understand the effectiveness of nutritional treatment strategies, we have performed a series of long-term dietary manipulation studies using our previously developed Tg-I278T Cbs(-/-) mouse model of CBS deficiency and sibling Tg-I278T Cbs(+/-) controls. Tg-I278T Cbs(-/-) mice have undetectable levels of CBS activity, extremely elevated plasma tHcy, modestly elevated plasma methionine, and low plasma cysteine. They exhibit several easily assayable phenotypes, including osteoporosis, loss of fat mass, reduced life span, and facial alopecia. The diets used in these studies differed in the amounts of sulfur amino acids or sulfur amino acid precursors. In this review, we will discuss our findings and their relevance to CBS deficiency and the concept of gene-diet interaction.

Successive MRI Findings of Reversible Cerebral White Matter Lesions in a Patient with Cystathionine ß-Synthase Deficiency.

Cystathionine ß-synthase (CBS) deficiency, well known as classical homocystinuria, is a rare autosomal recessive inborn error of homocysteine and sulfur metabolism. CBS converts homocysteine to cystathionine. The clinical features of untreated CBS deficiency include myopia, ectopia lentis, mental retardation, skeletal anomalies resembling Marfan syndrome, and thromboembolic events. Cerebral white matter lesions (CWMLs), identified in magnetic resonance imaging (MRI), are related to various clinical conditions including ischemia, inflammation, demyelination, infection, a tumor, and metabolic disorders such as phenylketonuria. The presence of CWMLs is, however, believed to be a very rare condition in CBS-deficient patients. Herein, we report reversible CWMLs associated with hypermethioninemia caused by poor protein restriction and betaine therapy in a 21-year-old male with pyridoxine-nonresponsive CBS deficiency. T2-weighted images (T2WI) and fluid-attenuated inversion-recovery (FLAIR) images showed diffuse high signal intensity in subcortical areas extending to the deep white matter. Diffusion-weighted images (DWI) showed high signal intensity, while apparent diffusion coefficient (ADC) map demonstrated decreased ADC value in the lesions. The course of improvement after correct methionine restriction was successively followed by brain MRI. The CWMLs had regressed at 1 month after restriction, and disappeared after 5 months. ADC values were very low before proper methionine restriction, but normalized after 2 months. Use of betaine in the presence of elevated plasma methionine may increase the risk of reversible CWMLs in some CBS-deficient patients.

Cystathionine ß-synthase-deficient mice thrive on a low-methionine diet.

Cystathionine ß-synthase (CBS) deficiency is a recessive inborn error of metabolism characterized by elevated serum total homocysteine (tHcy). Previously, our laboratory developed a mouse model of CBS deficiency, TgI278T Cbs(-)/(-) (abbreviated as Cbs(-/-)), characterized by low weight, low adiposity, decreased Scd-1 expression, facial alopecia, and osteoporosis. To determine the potential benefit of a methionine-restricted diet (MRD), we fed Cbs(-/-) and Cbs(+/-) control mice either an MRD or a regular diet (RD) from weaning till 240 d of age. Cbs(-/-) mice fed the MRD had a 77% decrease in tHcy, 28% increase in weight, 130% increase in fat mass, 82% increase in Scd-1 expression, and 10.6% increase in bone density and entirely lacked the alopecia phenotype observed in age-matched Cbs(-/-) mice fed the RD. At the end of the study, Cbs(-/-) mice fed the MRD were phenotypically indistinguishable from Cbs(+/-) mice fed the RD. Notably, whereas the MRD diet was highly beneficial to Cbs(-/-) mice, it had nearly opposite effect on Cbs(+/-) mice. These studies show that a low-methionine diet can correct the phenotypic consequences of loss of CBS and provide a striking example of how genotype and diet can interact to influence phenotype in mammals.

Dietary practices in pyridoxine non-responsive homocystinuria: a European survey.

BACKGROUND: Within Europe, the management of pyridoxine (B6) non-responsive homocystinuria (HCU) may vary but there is limited knowledge about treatment practice. AIM: A comparison of dietetic management practices of patients with B6 non-responsive HCU in European centres. METHODS: A cross-sectional audit by questionnaire was completed by 29 inherited metabolic disorder (IMD) centres: (14 UK, 5 Germany, 3 Netherlands, 2 Switzerland, 2 Portugal, 1 France, 1 Norway, 1 Belgium). RESULTS: 181 patients (73% >16 years of age) with HCU were identified. The majority (66%; n=119) were on dietary treatment (1-10 years, 90%; 11-16 years, 82%; and >16 years, 58%) with or without betaine and 34% (n=62) were on betaine alone. The median natural protein intake (g/day) on diet only was, by age: 1-10 years, 12 g; 11-16 years, 11 g; and >16 years, 45 g. With diet and betaine, median natural protein intake (g/day) by age was: 1-10 years, 13 g; 11-16 years, 20 g; and >16 years, 38 g. Fifty-two percent (n=15) of centres allocated natural protein by calculating methionine rather than a protein exchange system. A methionine-free l-amino acid supplement was prescribed for 86% of diet treated patients. Fifty-two percent of centres recommended cystine supplements for low plasma concentrations. Target treatment concentrations for homocystine/homocysteine (free/total) and frequency of biochemical monitoring varied. CONCLUSION: In B6 non-responsive HCU the prescription of dietary restriction by IMD centres declined with age, potentially associated with poor adherence in older patients. Inconsistencies in biochemical monitoring and treatment indicate the need for international consensus guidelines.

Neurologic and neurodevelopmental phenotypes in young children with early-treated combined methylmalonic acidemia and homocystinuria, cobalamin C type.

Abnormal neurodevelopment has been widely reported in combined methylmalonic aciduria (MMA) and homocystinuria, cblC type (cblC disease), but neurodevelopmental phenotypes in cblC have not previously been systematically studied. We sought to further characterize developmental neurology in children with molecularly-confirmed cblC. Thirteen children at our center with cblC, born since implementation of expanded newborn screening in New York State, undertook standard-of-care evaluations with a pediatric neurologist and pediatric ophthalmologist. At most recent follow-up (mean age 50 months, range 9-84 months), of twelve children with early-onset cblC, three (25%) had a history of clinical seizures and two (17%) meet criteria for microcephaly. A majority of children had hypotonia and nystagmus. Twelve out of thirteen (92%) underwent neurodevelopmental evaluation (mean age 41 months; range 9-76 months), each child tested with standardized parental interviews and, where possible, age- and disability-appropriate neuropsychological batteries. All patients showed evidence of developmental delay with the exception of one patient with a genotype predictive of attenuated disease and near-normal biochemical parameters. Neurodevelopmental deficits were noted most prominently in motor skills, with relative preservation of socialization and communication skills. Nine children with early-onset cblC underwent magnetic resonance imaging and spectroscopy (MRI/MRS) at mean age of 47 months (range 6-81 months); common abnormalities included callosal thinning, craniocaudally short pons, and increased T2 FLAIR signal in periventricular and periatrial white matter. Our study further characterizes variable neurodevelopmental phenotypes in treated cblC, and provides insights into the etiopathogenesis of disordered neurodevelopment frequently encountered in cblC. Plasma homocysteine and MMA, routinely measured at clinical follow-up, may be poor predictors for neurodevelopmental outcomes. Additional data from large, prospective, multi-center natural history studies are required to more accurately define the role of these metabolites and others, as well as that of other genetic and environmental factors in the etiopathogenesis of the neurologic components of this disorder.

Homocistinuria; curso clínico y tratamiento dietético; a propósito de dos casos / Clinical management of homocystinuria; case report and review of the literature

La homocistinuria es un error congénito del metabolismo de la metionina que conduce al acúmulo de metionina y de su principal metabolito, homocisteína, en plasma, orina y tejidos. El acúmulo de homocisteína posee toxicidad sobre los sistemas óseo (osteoporosis), ocular (luxación del cristalino), nervioso (convulsiones, alteraciones psiquiátricas) y vascular (accidentes cerebrovasculares, enfermedad cardiovascular). Presentamos 2 casos de homocistinuria en 2 pacientes hermanos y, a continuación, revisamos las estrategias terapéuticas disponibles (AU)

Homocystinuria is a congenital disorder of methyonine metabolism that leads to increased plasmatic, urinary and tissue deposits of methyonine and its main metabolite: homocysteine. Homocysteine deposits are toxic for the skeletal system (osteoporosis), the eyes (lens dislocation), central nervous system (seizures, psychiatric disorders) and also induce vascular damage (stroke and other cardiovascular events). This article reports two patients with homocystinuria in two siblings, followed by a concise review on the therapeutic strategies available for this disorder (AU)

Treatment of inherited homocystinurias.

Inherited homocystinurias, have in common, accumulation of homocysteine with subsequent neurotoxicity; they also encompass two distinctive clinical entities: classical homocystinuria due to cystathionine ß-synthase (CBS) deficiency and the rare inborn errors of cobalamin and folate metabolism. In the latter group, remethylation disorders of homocysteine to methionine (chiefly CblC defect and 5,10-methylenetetrahydrofolate reductase [MTHFR] deficiency) are by far the most frequently encountered situations. The natural history of CBS deficiency is relatively well known and described. Similarly, clinical presentations of remethylation defects are becoming better recognized and reported. Conversely, few data are available regarding treatment of these disorders, especially for remethylation defects. In this review, after an overview of the metabolic pathophysiology and the clinical features of inherited homocystinurias due to CBS deficiency, CblC defect, and MTHFR deficiency, we focus on present and prospective therapeutic approaches.

Homocystinuria and oral health. A report of 14 cases.

The aim of this study was to explore the oral health in Swedish individuals with the diagnosis of homozygote cystathionine beta synthase-deficient homocystinuria (HC), a rare disorder of amino acid metabolism affecting connective tissue, in which the phenotypic abnormalities include dislocation of the optic lens, skeletal abnormalities, thromboembolic events, and sometimes mental retardation. Further aims were to evaluate the oral findings against previous oral observations in a medical case report, such as high narrow palate, mandibular prognathia, crowding and early eruption of teeth. Every hospital in Sweden was contacted, with the inquiry of patients with diagnosis of HC,which resulted in 14 individuals participating in oral clinical examination. The oral findings evaluated against previous medical case reports showed to be partly in accordance with previous observations. Dental health showed to be compromised in a majority of cases. Together with the fact that methionine restriction (low-protein diet) is involved in the treatment of the condition and might result in a diet high in sugars, this points out the role of regular dental checkups and preventive oral care for individuals suffering from HC. In addition, short dental roots were a finding not previously reported in the literature. All the studied cases had central maxillary incisors with short roots, when compared to reference values used.

Altered expression of apoA-I, apoA-IV and PON-1 activity in CBS deficient homocystinuria in the presence and absence of treatment: possible implications for cardiovascular outcomes.

Classical homocystinuria (HCU) is caused by mutations in cystathionine beta-synthase (CBS) which, if untreated, typically results in cognitive impairment, thromboembolic complications and connective tissue disturbances. Paraoxonase-1 (PON1) and apolipoprotein apoA-I are both synthesized in the liver and contribute to much of the cardioprotective effects of high density lipoprotein. Additionally, apoA-I exerts significant neuro-protective effects that act to preserve cognition. Previous work in a Cbs null mouse model that incurs significant liver injury, reported that HCU dramatically decreases PON1 expression. Conflicting reports exist in the literature concerning the relative influence of homocysteine and cysteine upon apoA-I expression. We investigated expression of PON1 and apoA-I in the presence and absence of homocysteine lowering therapy, in both the HO mouse model of HCU and human subjects with this disorder. We observed no significant change in plasma PON1 paraoxonase activity in either mice or humans with HCU indicating that this enzyme is unlikely to contribute to the cardiovascular sequelae of HCU. Plasma levels of apoA-I were unchanged in mice with mildly elevated homocysteine due to CBS deficiency but were significantly diminished in both mice and humans with HCU. Subsequent experiments revealed that HCU acts to dramatically decrease apoA-I levels in the brain. Cysteine supplementation in HO mice had no discernible effect on plasma levels of apoA-I while treatment to lower homocysteine normalized plasma levels of this lipoprotein in both HO mice and humans with HCU. Our results indicate that plasma apoA-I levels in HCU are inversely related to homocysteine and are consistent with a plausible role for decreased expression of apoA-I as a contributory factor for both cardiovascular disease and cognitive impairment in HCU.

Liver transplantation for a patient with homocystinuria.

A 24-yr-old man was diagnosed with HCU during neonatal screening and remained on a pyridoxine, vitamin B12, folic acid, and betaine regimen with dietary methionine restriction for more than 10 yr. He had normal mental development, marfanoid appearance, myopia because of lens dislocation, and recurrent ankle subluxation during adolescence. Thereafter, he was a poor adherent to the conventional diet-restrictive therapy, and LT was considered when he developed hypertension and multiple infarctions over the right cerebellum early in the second decade of his life despite taking aspirin as a prophylaxis from 17 yr of age. In November 2009, he received a deceased whole LT from a blood group compatible donor. Along with the success of the transplantation, he was completely disease free without dietary or nutritional control. To the best of our knowledge, this is the first case of LT intended to cure HCU, and with promising results. This case provides an insight into the role of LT for this congenital metabolic disease, for which the decision should be made by judging between the severity of the disease and the risk of the operation, as well as the life quality of the patient.

[Clinical management of homocystinuria: case report and review of the literature]. / Homocistinuria; curso clínico y tratamiento dietético: a propósito de dos casos.

Homocystinuria is a congenital disorder of methyonine metabolism that leads to increased plasmatic, urinary and tissue deposits of methyonine and its main metabolite: homocysteine. Homocysteine deposits are toxic for the skeletal system (osteoporosis), the eyes (lens dislocation), central nervous system (seizures, psychiatric disorders) and also induce vascular damage (stroke and other cardiovascular events). This article reports two patients with homocystinuria in two siblings, followed by a concise review on the therapeutic strategies available for this disorder.

Production of synthetic methionine-free and synthetic methionine-limited alpha casein: protein foodstuff for patients with homocystinuria due to cystathionine beta-synthase deficiency.

The aim of this study was to evaluate the possibility that synthetic forms of methionine-free alpha-casein and methionine-limited alpha casein could be produced by recombinant means to form the basis for developing an industrial-scale process for the provision of a foodstuff suitable for patients with homocystinuria due to cystathionine beta-synthase (CBS) deficiency. As a first step, two forms of alpha casein gene, encoding methionine-free alpha casein (Fcas) or a methionine-limited alpha casein (Mcas), were synthesised and expressed in Escherichia coli. Using the overexpression vector pET28a, both genes were highly expressed in E. coli in soluble form as well as in inclusion bodies. The two recombinant proteins were purified by the one step methods using the fused His-tag and the Ni(2+)column and validated by Western blot analysis. This work paves the way for industrial-scale production of proteins suitable for patients with homocystinuria due to CBS deficiency.

Two successful pregnancies in pyridoxine-nonresponsive homocystinuria.

Two successful pregnancies are reported in a pyridoxine-nonresponsive woman who was also homozygous for the MTHFR 677C>T polymorphism. Two healthy children were delivered, although there had also been an early miscarriage of an apparently normal fetus in another pregnancy. Management of the patient's homocystine and methionine levels was maintained throughout pregnancy and, in view of the increased thromboembolic risk, anticoagulation therapy was also included in management.