Phenotyping mitochondrial glutamyl-tRNA synthetase deficiency (EARS2): A case series and systematic literature review.

Mitochondrial glutamyl-aminoacyl tRNA synthetase deficiency, stemming from biallelic mutations in the EARS2 gene, was first described in 2012. With <50 cases reported globally, this condition exhibits a distinct phenotype of neonatal or childhood-onset, often referred to as leukoencephalopathy with thalamus and brainstem involvement and high lactate (LTBL). It has also been one of the few reversible mitochondrial disorders described. The natural history of these patients is poorly documented, ranging from clinical and radiological improvement to early death. Herein, we detail three cases from our centre, including follow-up on the Portuguese patient reported by Steenweg et al., These cases illustrate the phenotypic spectrum: i) rapidly progressive neonatal presentation with lactic acidemia and corpus callosum agenesis, leading to early death; ii) early onset with a severe, slowly progressive course; iii) early onset with a milder phenotype, showing some improvement and mild neurological symptoms. Additionally, we conducted a systematic literature review on cases of EARS2-deficient patients, focusing on clinical manifestations, laboratory findings, radiological aspects, and disease progression over time, along with respective data analysis. "Patients with EARS2 deficiency typically present within the first year of life with a well-defined neurometabolic disorder picture, often including hypotonia and/or spasticity, along with neurodevelopmental delay or regression. There are no pathognomonic features specific to EARS2 deficiency, and no genotype-phenotype correlation has been identified." Comparing to initial characterization by Steenweg et al., this analysis reveals an expanded disease spectrum. We propose a novel strategy for clustering phenotypes into severe, moderate, or mild disease based on initial presentation, seemingly correlating with disease progression. The paucity of data on the disease's natural history highlights the need for a multicentric approach to enhance understanding and management. TAKE-HOME MESSAGE: Analysis of all cases published with EARS2 deficiency allows for establish disease spectrum and a novel strategy for clustering phenotypes which correlate to disease progression.

Portuguese Neonatal Screening Program: A Cohort Study of 18 Years Using MS/MS.

The Portuguese Neonatal Screening Program (PNSP) conducts nationwide screening for rare diseases, covering nearly 100% of neonates and screening for 28 disorders, including 24 inborn errors of metabolism (IEMs). The study's purpose is to assess the epidemiology of the screened metabolic diseases and to evaluate the impact of second-tier testing (2TT) within the PNSP. From 2004 to 2022, 1,764,830 neonates underwent screening using tandem mass spectrometry (MS/MS) to analyze amino acids and acylcarnitines in dried blood spot samples. 2TT was applied when necessary. Neonates with profiles indicating an IEM were reported to a reference treatment center, and subsequent biochemical and molecular studies were conducted for diagnostic confirmation. Among the screened neonates, 677 patients of IEM were identified, yielding an estimated birth prevalence of 1:2607 neonates. The introduction of 2TT significantly reduced false positives for various disorders, and 59 maternal cases were also detected. This study underscores the transformative role of MS/MS in neonatal screening, emphasizing the positive impact of 2TT in enhancing sensitivity, specificity, and positive predictive value. Our data highlight the efficiency and robustness of neonatal screening for IEM in Portugal, contributing to early and life-changing diagnoses.

History of Neonatal Screening of Congenital Hypothyroidism in Portugal.

Congenital hypothyroidism (CH) leads to growth and development delays and is preventable with early treatment. Neonatal screening for CH was initiated in Portugal in 1981. This study examines the history of CH screening in the country. Data were obtained from annual reports and from the national database of neonatal screening laboratory. The CH screening strategy primarily relies on the thyroid-stimulating hormone (TSH), followed by total thyroxine measurement as the second tier for confirmation. The TSH cutoff started at 90 mIU/L, decreasing to the actual 10 mIU/L. The coverage of the screening program has increased rapidly; although voluntary, it reached about 90% in 6 years and became universal in 10 years. Guideline and cutoff updates led to the identification of over 200 additional cases, resulting in specific retesting protocols for preterm and very-low-birth-weight babies. The actual decision tree considers CH when TSH levels are above 40 mIU/L. Data from the CH screening also provide an indication of the iodine status of the population, which is presently indicative of iodine insufficiency. The Portuguese neonatal screening for CH is a history of success. It has rapidly and continuously adapted to changes in knowledge and has become a universal voluntary practice within a few years.

Iodineminho Study: Iodine Supplementation and Prevalence of Iodine Deficiency in Pregnant Women.

CONTEXT: Iodine is necessary for the proper brain development. The prevalence of iodine deficiency in Portuguese pregnant women led the health authorities, in 2013, to recommend iodine supplementation for women in preconception, throughout pregnancy and during lactation. OBJECTIVE: To assess the impact of iodine supplementation initiated in the preconception or the first trimester of pregnancy on the prevalence of iodine deficiency and maternal thyroid status. METHODS: An observational prospective cohort study that follows thyroid function and iodine status of women recruited in preconception or in the first trimester of pregnancy. RESULTS: The median urinary iodine concentration (UIC) was significantly higher among women taking iodine supplements (no-supplement group UIC=63µg/L; supplement group UIC =100µg/L, p = 0.002) but still below the levels recommended by the World Health Organization. Only 15% of pregnant women had adequate iodine status and 17% showed UIC < 50 µg/l. There was no influence of whether iodine supplementation started in preconception or in the 1st trimester of gestation (UIC preconception group: 112µg/L vs UIC pregnancy group: 91µg/L, p = 0.569). In the 1st trimester of pregnancy, total thyroxine levels were lower and free triiodothyronine levels were higher in non-supplemented women. Thyroglobulin levels were lower in women who started iodine supplementation in preconception compared to non-supplemented women and women who started iodine supplementation during gestation. CONCLUSION: In the Minho region of Portugal, fertile women have insufficient iodine intake. Additional public health measures are needed since the current recommendations for iodine supplementation for pregnancy are unsatisfactory to achieve an adequate iodine status.

Pharmacogenetic Variants Can Influence Optical Medication Use.

INTRODUCTION: Single Nucleotide Polymorphisms (SNPs) are used as drug susceptibility biomarkers in metabolic diseases. Alterations in the gene encoding triggers the enzyme flavin monooxygenase 3 (FMO3), involved in the Sulindac metabolization, which also is responsible for the inherited metabolic disorder. Trimethylaminuria (TMAu, OMIM: 602079). DPYD gene variants are associated with the enzyme dihydropyrimidine dehydrogenase deficiency (DPD; OMIM: 274270). This autosomal recessive metabolic disorder, ultimately leads to the inability to metabolize fluoropyrimidines, which causes severe toxicity in individuals treated with these drugs. METHODS: Variants in genes responsible for the expression of enzymes that encode transporters or receptors involved in the metabolization pathways of certain drugs may condition the individuals response to certain drugs, compromising the therapeutic response and clinical prognosis. Thus the sequencing and identification of variants become relevant, not only gain knowledge on effects of these variants' on disease causality but also in terms of its side effects resulting from the coding enzymes responsible for drug metabolization. RESULTS: It was found that patients with the c.472G>A (p.Glu158Lys) and c.923A>G (p.Glu308Gly) polymorphisms, in homozygosity, in FMO3 gene did not develop polyps, thus have a protective effect in the treatment of Familial Adenomatous Polyposis (PAF). However, in the case of the DPYD gene, c.1905+1G>A (IVS14+1G>A), c.1679T>G (p.Ile560Ser), c.2846A>T (p.Asp949Val) e c.1236G>A/HapB3 variants can be lethal in cancer patients indicated for fluoropyrimidine-based chemotherapy. CONCLUSION: Knowledge on the drug mechanisms will affect the therapeutic response of patients treated with a given drug. Thus, pharmacogenetics is an essential tool in personalized medicine, since molecular studies allows the clinician to predict the probability of efficacy and toxicity of certain drugs, resulting higher efficiency in individualizing treatment and also improving the safety of the patient. From a personalized medicine perspective, the study of the characteristics of the drug and its metabolization site, the genes involved in the encoding of enzymes responsible for its metabolization will be of great interest.

Tyrosinemia type iii: a case report of siblings and literature review / Tirosinemia tipo iii: descrição de caso clínico em irmãos e revisão da literatura

ABSTRACT Objective: Tyrosinemia type III (HT III) is the rarest form of tyrosinemia, and the full clinical spectrum of this disorder is still unknown. The neurological involvement varies, including intellectual impairment and attention deficit disorder with hyperactivity (ADHD). We report the case of two siblings diagnosed with HT III at different ages. Case description: The index case was diagnosed by newborn screening for endocrine and metabolic disorders, starting a low-protein diet immediately, with a consistent decrease in tyrosine levels. By the age of three, the child displayed a hyperactive behavior, starting treatment for ADHD two years later. At seven years of age, he shows a slight improvement in terms of behavior and attention span and has a cognitive performance slightly lower than his peers, despite maintaining acceptable tyrosine levels. His sister, who had a history of ADHD since age five, was diagnosed with HT III after family screening at the age of eight. Despite initiating a dietetic treatment, her behavior did not improve, and she has a mild intellectual impairment. Comments: This is the first case report describing siblings with HT III who underwent nutritional treatment with a low-protein diet in different phases of life, with a better neurological and behavioral evaluation in the patient who started treatment earlier.

RESUMO Objetivo: A tirosinemia tipo III (TT III) é a forma mais rara das tirosinemias e o espectro clínico desta entidade não está totalmente esclarecido. O envolvimento neurológico é variável, incluindo o atraso cognitivo ou transtorno do déficit de atenção com hiperatividade (TDAH). Descrevemos o caso de dois irmãos que foram diagnosticados com TT III em idades diferentes. Descrição dos casos: O caso índice foi diagnosticado no contexto do rastreio endócrino-metabólico neonatal, tendo iniciado imediatamente dieta hipoproteica, com redução consistente dos níveis de tirosina. Por volta dos três anos, foi detectado um comportamento hiperativo, tendo iniciado dois anos depois tratamento para o TDAH. Aos sete anos, apresenta leve melhora de comportamento e da atenção e avaliação cognitiva levemente inferior ou pouco abaixo quando comparado a crianças da mesma faixa etária, apesar de manter níveis aceitáveis de tirosina. A sua irmã, com história de TDAH desde os cinco anos, foi diagnosticada de TT III aos oito anos no contexto do rastreio de familiares. Apesar de iniciar tratamento dietético, nenhum efeito foi notado em termos de comportamento e a doente apresenta leve atraso cognitivo. Comentários: Este é o primeiro caso clínico descrito de irmãos com TT III que iniciaram terapêutica dietética com dieta hipoproteica em diferentes fases da vida, com melhor avaliação em termos neurológicos e comportamentais no doente que iniciou tratamento mais precocemente.

Leigh Syndrome Due to mtDNA Pathogenic Variants

Abstract Leigh syndrome is a devastating neurodegenerative disease, typically manifesting in infancy or early childhood. Hallmarks of the disease are symmetrical lesions in the basal ganglia or brain stem on MRI, and a clinical course with rapid deterioration of cognitive and motor functions. It is genetically heterogeneous, causative mutations have been disclosed in mitochondrial DNA and nuclear genes involved in the process of energy production in the mitochondria .We investigated the whole mitochondrial DNA in three Brazilian patients with LS, based on their clinical and biochemical data, with the aim to identify the disease-causing mutations. In two of the patients, with complex I deficiency, a novel heteroplasmic variant m.4142G>T (p.R279L) in MT-ND1 and a recurrent homoplasmic mutation m.10197G>A (p.A47T) in MT-ND3 were identified. In the remaining patient, with complex IV deficiency, a de novo heteroplasmic variant in MT-CO1 m.6547T>C (p.L215P) was found. The molecular investigation in mitochondrial diseases have shifted their focus from mitochondrial DNA to nuclear DNA, however, mtDNA protein-coding genes are one of the important genetic causes of mitochondrial disorders for Leigh syndrome. This study expands the molecular and clinical spectrum associated with this disease.

Síndrome de leigh: a propósito de um caso clínico com mutação no dna mitocondrial / Leigh syndrome: a case report with a mitochondrial dna mutation

RESUMO Objetivo: A síndrome de Leigh é uma doença neurodegenerativa com incidência de 1:40.000 nados-vivos. Apresenta ampla heterogeneidade clínica, bioquímica e genética, mas com alterações neuropatorradiológicas homogêneas. Não existe tratamento específico, e o prognóstico é reservado. O objetivo deste estudo foi familiarizar os profissionais de saúde com a doença. Descrição do caso: Menina de 16 meses, com hipotonia axial e atraso do desenvolvimento psicomotor. Dos exames realizados: cariótipo, potenciais auditivos evocados e avaliação oftalmológica normais; presença de hiperlactacidemia e hipocitrulinemia. Após a realização de ressonância magnética cerebral sob anestesia, observou-se agravamento da hipotonia com necessidade de internação por episódios de cianose/apneia. O eletroencefalograma não mostrou atividade epileptiforme. A neuroimagem revelou hipersinal lenticular bilateral com lesão do putâmen e do globo pálido esquerdo. Encontrou-se a mutação 8993T>G (MT-ATP6) no DNA mitocondrial. Comentários: De 10 a 30% dos doentes com síndrome de Leigh apresentam mutações do DNA mitocondrial. A descompensação com agravamento neurológico após intervenção anestésica está descrita e, nesse caso, apoiou o diagnóstico. Importante alertar para casos semelhantes, com diminuição de exames invasivos para diagnóstico.

ABSTRACT Objective: Leigh syndrome is a neurodegenerative disorder with an incidence of 1:40,000 live births. It presents wide clinical, biochemical, and genetic heterogeneity, but with homogenous neuropatoradiological alterations. There is no specific treatment, and the prognosis is reserved. This case report aimed familiarize health professionals with the disease. Case Description: A 16-month-hold girl who was followed in outpatient clinic due to axial hypotonia and delayed psychomotor development. Karyotype, auditory evoked potentials and ophthalmologic evaluation were normal. Evidence of hyperlactacidemia and hypocitrullinemia was detected in the patient. After performing brain magnetic resonance under anesthesia, hypotonia got worse, and the patient was hospitalized after an episode of cyanosis and apnea. The electroencephalogram showed no epileptiform activity. Neuroimaging revealed bilateral lenticular hyperintensity, especially in the putamen and in the left globus pallidus regions. Molecular analysis revealed an 8993T>G (MT-ATP6) mutation in the mitochondrial DNA. Comments: Between 10 and 30% of individuals with Leigh syndrome have mitochondrial DNA mutations. The decompensation after anesthetic intercurrences is typically associated with neurological deterioration and, in this case, increased the diagnosis suspicion. It is important to alert for similar cases and to reduce invasive diagnostic tests if the diagnosis is suspected.