The cobalamin C deficiency (CblCD) is the most common inborn error of the cobalamin metabolism. It is characterized by inability to convert dietary vitamin B12 into the coenzymes adenosylcobalamin and methylcobalamin, in cell. The former is crucial for the activity of methylmalonyl CoA mutase and the later for methionine synthase. Their deficit leads to accumulation of methylmalonic acid (MMA) and homocysteine, respectively. They have a toxic effect in various systems, including the nervous system and eye. Besides these products, disease can be detected by an increase of propionylcarnitine and diagnosed by identification of biallelic pathogenic variants in the MMACHC gene. Treatment consists in a combination of vitamin B12 and betaine. The benefits of folic acid supplementation and protein restricted diet are limited. Despite therapy, prognosis is poor, especially in the early onset phenotype.The goals of the present work were to describe the clinical presentation, diagnosis, treatment and disease progression of children (less than 18 years old) with an established diagnosis of CblCD, followed at Centro de Referência de Doenças Hereditárias do Metabolismo do Centro Hospitalar Universitário de Coimbra, between 2002 and 2021 (20 years).In the defined period, CblCD was diagnosed in five children, one of them presented symptoms before birth, while the other four were diagnosed by the Programa Nacional de Rastreio Neonatal. All presented the same mutation, (c.271dupA), in MMACHC gene.All the patients of our cohort presented clinic in the first weeks of life. The first manifestation of the disease was hypotonia in all patients. Some of them, also presented feeding difficulties, metabolic acidosis and seizures. With increasing age, all manifested ophthalmological and neurological features and three presented cardiovascular manifestations. All children presented global development delay, which is very common in this disorder. One child presented concomitant Type 1 Diabetes Mellitus, which to our knowledge, this association had never been reported. Two children have died. No correlation was found between MMA levels and date of onset or severity of the clinical manifestations. Methionine and homocysteine levels at presentation did not correlate with clinical severity. In spite of early treatment normal amino acids levels were never achieved, except for methionine.The current base of CblCD treatment is hydroxocobalamin and betaine. Folic acid and oral metronidazole were also used, despite the fact that their effectivity in CblCD is not consensual.Although the disease has progressed in all cases, the three living patients remain apparently stable. The youngest has a significant global development delay/intellectual disability. The others, who attend regular school with good performance, although needing visual aids, live a close to normal life.

ABSTRACT Homocystinuria is a treatable autosomal recessive inherited disorder. This condition may cause life-threatening complications such as thromboembolic events. Coronavirus disease 2019 (COVID-19) is associated with an increased risk of venous thromboembolic events. Here, we report a case of late diagnosis of homocystinuria presenting with deep venous thrombosis and COVID-19. This study highlights a sustained high index of suspicion for homocystinuria to prevent severe thromboembolic complications.

ABSTRACT Purpose: Artisan iris-claw lens implantation (AICLI) is a surgical technique for treating ectopia lentis. We aimed to compare visual outcomes and possible long-term complications of AICLI surgery in pediatric patients with ectopia lentis with or without a diagnosable hereditary disease. Methods: Seventeen children with non-traumatic ectopia lentis were retros pectively classified into two groups: group 1 included children with a diagnosable hereditary disease (11 patients, 65%), and group 2 included children without any definable hereditary disease (six patients, 35%). Patients were evaluated for post-surgical refraction, best-corrected visual acuity, and clinical follow-up complications. Results: The average follow-up time was 38 months, and the average age of the patients was 103 ± 53 months (30-196 months). Best-corrected visual acuity values were significantly increased in both groups after surgery (p<0.05). Target refraction values were achieved at a rate of 47% in group 1 and 22% in group 2. Post-surgery complications, such as lens dislocation (36%, 11 eyes of 10 patients) and hypotonia (10%, three eyes of three patients) were observed in both groups, and retinal detachments (10%, three eyes of three patients) were observed in three patients from group 1. Conclusions: Compared with previous similar studies, this study utilized the largest pediatric patient group and had the longest post-surgery follow-up time. Moreover, it is advisable that pediatric patients with non-traumatic ectopia lentis be carefully screened for any underlying hereditary disease, especially diseases related to connective tissue metabolism.

A Homocistinúria clássica é uma doença genética causada pela deficiência parcial ou total da atividade da enzima cistationina-β sintase (CβS). Bioquimicamente, ela é caracterizada por distúrbios no metabolismo dos aminoácidos sulfurados, com elevação plasmática de homocisteína e metionina e redução de cistationina e cisteína. Esse distúrbio metabólico afeta principalmente os sistemas cardiovascular, muscular e nervoso central. Retardo mental, deficiência cognitiva, prejuízos na memória, crises convulsivas, atrofia cerebral e doença aterosclerótica precoce são as manifestações clínicas mais comuns em pacientes homocistinúricos. A prevalência da homocistinúria é de cerca de 1/300.000 nascimentos em todo o mundo. Atualmente o tratamento consiste na redução dos níveis de homocisteína através de dietas pobres em metionina e suplementação com piridoxina (cofator da CβS), betaína, ácido fólico e vitamina B12, mas nem todos os pacientes respondem ao tratamento. Diversos estudos têm sugerido o enriquecimento ambiental como alternativa não farmacológica à terapêutica dos prejuízos cognitivos e neuromotores causados pelos processos neurodegenerativos. Desta forma, o objetivo principal desse trabalho foi investigar os possíveis efeitos benéficos causados pela exposição ao ambiente enriquecido sobre as alterações do comportamento e da motricidade (spatial memory) causados pela hiperhomocisteinemia induzida quimicamente em roedores. Utilizamos um modelo experimental de hiper-homocisteinemia severa crônica em ratos Wistar desenvolvido em nosso laboratório. Nesse modelo, os animais foram submetidos ao tratamento com homocisteína administrada por via subcutânea com intervalos de 12 horas entre cada administração, do 6º ao 28º dia de vida, após esse período, os animais foram expostos ao ambiente enriquecido por 30 dias, posteriormente foi avaliado a performance dos animais em testes de comportamento. Os animais do grupo hiper-homocisteinemia apresentaram prejuízo no aprendizado na tarefa do labirinto aquático de Morris. A hiper-homocisteinemia não alterou a locomoção no campo aberto nem na tarefa da escada horizontal e a tarefa de reconhecimento de novo objeto. O enriquecimento ambiental foi capaz de reverter os danos observados na memória espacial, avaliada pelo labirinto aquático de Morris, e de melhorar o desempenho dos animais no teste da caminhada sobre a escada horizontal, melhorando qualidade de passo e reduzindo os erros de travessia e melhorando a memória de reconhecimento. Considerando que o enriquecimento ambiental é um tratamento não invasivo, nossos achados sugerem que o enriquecimento ambiental possa ser utilizado como uma terapia alternativa para tratar os prejuízos de memória e motricidade encontrados em pacientes homocistinúricos.

O acúmulo tecidual de homocisteína (Hcy) ocorre na homocistinúria clássica, um erro inato do metabolismo dos aminoácidos. Pacientes afetados por esta doença apresentam alterações neurológicas e cardiovasculares. Os mecanismos pelos quais a Hcy exerce os efeitos neuro e cardiotóxicos ainda não foram totalmente esclarecidos, entretanto, alguns trabalhos mostram que a hiper-homocisteínemia crônica induz estresse oxidativo e altera parâmetros inflamatórios em cérebro e coração de ratos. Por outro lado, o ácido acetilsalicílico (AAS) apresenta ação anti-inflamatória e antioxidante. O objetivo do presente estudo foi avaliar os efeitos do pré-tratamento com AAS sobre parâmetros de estresse oxidativo no coração de ratos submetidos à administração aguda de Hcy. Ratos Wistar de 22 dias receberam pré-tratamento com AAS (100mg/Kg) e/ou solução de bicarbonato de sódio 1,1% (controle) uma vez ao dia pela via intraperitoneal durante 7 dias; no 8º dia receberam uma única injeção subcutânea de Hcy (0,6 μmol /g peso corporal) ou solução de bicarbonato de sódio tamponada. Uma hora após a injeção, os ratos foram mortos e o coração dissecado. Os resultados demonstraram que a administração aguda de Hcy alterou os parâmetros de estresse oxidativo, além de aumentar a atividade da superóxido dismutase e diminuir a atividade da catalase. Em contraste, não houve alteração na atividade da glutationa peroxidase. O AAS preveniu todas as alterações causadas pela Hcy sobre os parâmetros avaliados. Nossos estudos demonstram que o pré-tratamento com AAS preveniu a indução do estresse oxidativo causada pela Hcy em coração de ratos, provavelmente devido às suas propriedades antioxidantes.

Homocystinuria is an inborn error of amino acid metabolism caused by deficiency of cystathionine ß-synthase (CBS) activity, leading to the accumulation of homocysteine (Hcy) and methionine (Met) in biological fluids and high urinary excretion of homocystine (Hci). This accumulation leads to a variety of clinical manifestations, in different organs and tissues, as thinning and lengthening of the long bones, osteoporosis, dislocation of the ocular lens, thromboembolism and mental retardation, but the pathophysiology of this disease is not completely understood. In this context, this review addresses some findings obtained from patients and animal studies indicating that oxidative stress plays an important role in the pathophysiology of homocystinuria. Several studies have shown that enzymatic and non-enzymatic antioxidant defenses are decreased, as well as markers of lipid, protein, and DNA oxidative damage have been reported increased in blood, brain, liver and muscle in the animal models studied, as well as in homocystinuric patients, which may be due to an increased free radical generation or secondary to the deprivation of micronutrients which are essential for these defenses. A considerable set of data from in vitro and in vivo animal studies have shown that Hcy induces reactive species formation in brain rodent. Considering these findings, it is well established that oxidative stress may contribute to the damage found in homocystinuric patients. This review offers new perspectives for the treatment in homocystinuria, which may include the use of appropriate antioxidants as a novel adjuvant therapy for the patients.

Homocystinuria is an inborn error of metabolism most frequently caused by cystathionine β-synthase (CBS) deficiency. Homocysteine (Hcy), methionine (Met) and other metabolites of Hcy accumulate in the body of affected patients, leading to clinical manifestations such as dislocation of the optic lents, osteoporosis, mental retardation, and thromboembolism. Despite the fact that thromboembolism represent the major cause of morbidity and the most frequent cause of death in CBS-deficient patients, the cause of cardiovascular changes found in homocystinuria remain unclear. In this work, we evaluated the lipid profile (total cholesterol, HDL cholesterol, LDL cholesterol, oxidized LDL cholesterol, apolipoprotein A-1) and the activities of the enzymes paraoxonase (PON1) and butyrylcholinesterase (BuChE) in plasma of patients with homocystinuria due CBS deficiency, at diagnosis and during the treatment. It was verified a significant decrease in HDL cholesterol and apolipoprotein A1 levels in the both groups of CBS-deficient patients (at diagnosis and under treatment) when compared to controls. PON1 activity was also significantly lower in the both groups of CBS-deficient patients when compared to controls which may be related with an Hcy-dependent oxidation of any group important to catalytic activity of the enzyme that favors the atherogenesis. BuChE activity was significantly increased only in CBS-deficient patients at diagnosis and it is known that this enzymatic activity is positively associated with cardiovascular risk factors. Evaluated together, our results demonstrated that treated or not CBS-deficient patients presented important alterations in lipid metabolism. This work contributes to the understanding of the responsible mechanisms of vascular lesions in CBS-deficient patients.

Methylenetetrahydrofolate reductase (MTHFR) plays a major role in folate metabolism. Disturbed function of the enzyme results in hyperhomocysteinemia and causes severe vascular and neurological disorders and developmental delay. Five patients suspected of having non-classical homocystinuria due to MTHFR deficiency were examined with respect to their symptoms, MTHFR enzyme activity and genotypes of the MTHFR gene. All patients presented symptoms of severe central nervous system disease. Two patients died, at the ages of 15 months and 14 years. One patient is currently 32 years old, and is being treated with betaine and folinic acid. The other two patients, with an early diagnosis and a severe course of the disease, are currently improving under treatment. MTHFR enzyme activity in the fibroblasts of four of the patients was practically undetectable. We found four novel mutations, three of which were missense changes c.664G>T (p.V218L), c.1316T>C (p.F435S) and c.1733T>G (p.V574G), and the fourth was the 1-bp deletion c.1780delC (p.L590CfsX72). We also found the previously reported nonsense mutation c.1420G>T (p.E470X). All the patients were homozygous. Molecular modelling of the double mutant allele (p.V218L; p.A222V) revealed that affinity for FAD was not affected in this mutant. For the p.E470X mutation, the evidence pointed to nonsense-mediated mRNA decay. In general, genotype–phenotype analysis predicts milder outcomes for patients with missense changes than for those in which mutations led to severe alterations of the MTHFR protein.

Purpose: To assess how the current practice of newborn screening (NBS) for homocystinurias compares with published recommendations. Methods: Twenty-two of 32 NBS programmes from 18 countries screened for at least one form of homocystinuria. Centres provided pseudonymised NBS data from patients with cystathionine beta-synthase deficiency (CBSD, n = 19), methionine adenosyltransferase I/III deficiency (MATI/IIID, n = 28), combined remethylation disorder (cRMD, n = 56) and isolated remethylation disorder (iRMD), including methylenetetrahydrofolate reductase deficiency (MTHFRD) (n = 8). Markers and decision limits were converted to multiples of the median (MoM) to allow comparison between centres. Results: NBS programmes, algorithms and decision limits varied considerably. Only nine centres used the recommended second-tier marker total homocysteine (tHcy). The median decision limits of all centres were ≥ 2.35 for high and ≤ 0.44 MoM for low methionine, ≥ 1.95 for high and ≤ 0.47 MoM for low methionine/phenylalanine, ≥ 2.54 for high propionylcarnitine and ≥ 2.78 MoM for propionylcarnitine/acetylcarnitine. These decision limits alone had a 100%, 100%, 86% and 84% sensitivity for the detection of CBSD, MATI/IIID, iRMD and cRMD, respectively, but failed to detect six individuals with cRMD. To enhance sensitivity and decrease second-tier testing costs, we further adapted these decision limits using the data of 15 000 healthy newborns. Conclusions: Due to the favorable outcome of early treated patients, NBS for homocystinurias is recommended. To improve NBS, decision limits should be revised considering the population median. Relevant markers should be combined; use of the postanalytical tools offered by the CLIR project (Collaborative Laboratory Integrated Reports, which considers, for example, birth weight and gestational age) is recommended. tHcy and methylmalonic acid should be implemented as second-tier markers.