Hipoventilação relacionada ao sono de origem central secundária à deficiência de biotinidase: relato de caso / Sleep-related hypoventilation due to partial biotinidase deficiency: a case repor

RESUMO: A hipoventilação relacionada ao sono de origem central resulta em hipercapnia relacionada ao sono na vigência de condições normais do sistema respiratório e excluindo-se outros fatores. Os pacientes portadores dessa patologia podem se apresentar assintomáticos ou com queixas de cefaleia matinal, déficit cognitivo e fadiga, além de eventos como a observação de respiração superficial. No presente relato, descreve-se o caso de uma paciente de três anos, com exame físico geral e neurológico normais, desenvolvimento neuropsicomotor adequado, apresentando irregu-laridades respiratórias e bradicardia durante o sono. Encaminhada para investigação de distúrbios respiratórios do sono, sendo diagnosticada com hipoventilação relacionada ao sono. Através do estudo genético, evidenciou-se a deficiência de biotinidase como a possível causa da sintomatologia, comprovada por dosagens enzimáticas e teste genético molecular. O tratamento medicamentoso foi iniciado precocemente, determinando resolução dos sintomas descritos. A importância do presente relato se encontra na apresentação da deficiência da biotinidase com quadro cardiorrespiratório isolado em criança neurologicamente normal, ademais trata-se de um caso em que a etiologia de Breath-Holding Spells foi a deficiência dessa enzima. Correspondência sugerida pela resolução da hipoventila-ção central após a introdução da biotina. Além disso, nesse caso, os sintomas Apparent Life-Threatening Events, que aterrorizam o observador e até o profissional, foram solucionados com tratamento simples, a ingesta oral de biotina. Esse relato de caso corrobora com a expansão das possibilidades de manifestações fenotípicas das formas tardias de deficiência de biotinidase, como o fenótipo da Síndrome da Hipoventilação Central. (AU)

ABSTRACT: Idiopathic sleep-related hypoventilation occurs in individuals with hypercapnia during sleep in normal conditions of the respiratory system in the absence of other disorders. Patients with this condition may be asymptomatic or have complaints of morning headache, cognitive deficit and fatigue, and observation of shallow breathing. This report describes the case of a 3-year-old patient with normal physical and neurological exam, appropriate neuropsychomotor development, presenting breathing irregularities, and bradycardia during sleep. The patient was referred to an investigation for sleep respiratory disturbs and was diagnosed with hypoventilation related to sleep. The genetic study, done by enzymatic dosages and molecular genetic tests, showed the deficiency of biotinidase as a possible cause of symptomatology. The drug treatment was initiated early with the resolution of the symptoms. The present clinical report highlights the biotinidase deficiency with an isolated cardiorespiratory condition in a neurologically normal child, which also led to Breath-Holding Spells. This relation was suggested after central hypoventilation resolution following biotin introduction. Besides, Apparent Life-Threatening Events symptoms, which terrify the observer and even professionals, disappeared after the oral intake of biotin. Finally, this case report corroborates the expansion of possibilities for the phenotypic manifestations of late cases from biotinidase deficiency, as the SHC phenotyp. ((AU)

Expanded carrier screening for preconception reproductive risk assessment: Prevalence of carrier status in a Mexican population.

OBJECTIVE: Genetic carrier screening has the potential to identify couples at risk of having a child affected with an autosomal recessive or X-linked disorder. However, the current prevalence of carrier status for these conditions in developing countries is not well defined. This study assesses the prevalence of carrier status of selected genetic conditions utilizing an expanded, pan-ethnic genetic carrier screening panel (ECS) in a large population of Mexican patients. METHODS: Retrospective chart review of all patients tested with a single ECS panel at an international infertility center from 2012 to 2018 were included, and the prevalence of positive carrier status in a Mexican population was evaluated. RESULTS: Eight hundred five individuals were analyzed with ECS testing for 283 genetic conditions. Three hundred fifty-two carriers (43.7%) were identified with 503 pathogenic variants in 145 different genes. Seventeen of the 391 participating couples (4.34%) were identified as being at-risk couples. The most prevalent alleles found were associated with alpha thalassemia, cystic fibrosis, GJB2 nonsyndromic hearing loss, biotinidase deficiency, and familial Mediterranean fever. CONCLUSION: Based on the prevalence and severity of Mendelian disorders, we recommend that couples who wish to conceive regardless of their ethnicity background explore carrier screening and genetic counseling prior to reproductive medical treatment.

Frequency of biotinidase gene variants and incidence of biotinidase deficiency in the Newborn Screening Program in Minas Gerais, Brazil.

OBJECTIVE: The prevalence of biotinidase deficiency and the frequency of biotinidase gene variants in Brazil are not documented. We aimed to determine the incidence of partial and profound biotinidase deficiency in the state of Minas Gerais, Brazil, and to calculate the frequency of biotinidase gene variants in the newborn screening program of Minas Gerais. METHODS: Neonates (1,168,385) were screened from May 2013 to June 2018. Those detected with abnormal biotinidase activity based on semi-quantitative assays underwent confirmatory serum tests. The biotinidase gene was sequenced in all confirmed cases. RESULTS: The combined incidence of partial and profound biotinidase deficiency was estimated at 1:13,909 live births (95% confidence limit 1:11,235-1:17,217), much higher than the incidence rates reported in other populations worldwide. The most frequent biotinidase gene variants were p.D444H (allele frequency, 0.016), haplotype c.1330G>C;c.511G>A (p.D444H;A171T), p.D543E, c.310-15delT (intronic), p.V199M, and p.H485Q. Together these accounted for 74.6% of the alleles analysed. CONCLUSION: Newborn screening for biotinidase deficiency, which revealed a higher incidence in Minas Gerais, is feasible and plays a critical role in the early identification of affected neonates and prevention of symptoms and irreversible sequelae. Biotinidase gene sequencing is a useful tool to confirm the diagnosis, and also provides valuable information about genetic variability among different populations.

Effect of BTD gene variants on in vitro biotinidase activity.

INTRODUCTION: Biotinidase deficiency (BD), an autosomal recessive disease, is classified into profound (activity <10%) or partial BD (activity 10-30%). The most frequent variant in patients worldwide is c.1330G > C (p.Asp444His), which is associated with partial BD. In vivo studies indicate that this variant reduces the biotinidase activity by 50%. The objective of this study was to evaluate the in vitro effect of p.Asp444His and of five novel variants identified among Brazilian individuals showing low activity of biotinidase in serum. METHODS: The variants c.119 T > C (p.Leu40Pro), c.479G > A (p.Cys160Tyr), c.664G > A (p.Asp222Asn), c.1330G > C (p.Asp444His), c.1337 T > C (p.Leu446Pro), c.1466A > G (p.Asn489Ser) and the wild type (wt) BTD gene were expressed in HEK 293 cells. Biotinidase activity was quantified by colorimetric method in cells homogenates and culture medium. The wtBTD activity was considered 100%. RESULTS: The p.Leu40Pro, p.Cys160Tyr and p.Leu446Pro variants were associated to impaired biotinidase activity (activity in cells: 33%, 14%, 0%, respectively; activity in medium: 7%, 0.3%, 2%, respectively) and undetectable amount of protein in intra and extracellular space. The p.Asn489Ser variant had these effects restricted to the extracellular space (activity in medium: 43%), and the p.Asp222Asn variant showed normal activity. The expression of p.Asp444His variant resulted in detectable protein and slightly reduced activity only in cells (activity in cells: 46%; activity in medium: 115%). CONCLUSION: Our findings suggest that the p.Leu40Pro, p.Cys160Tyr and p.Leu446Pro variants are deleterious; the p.Asn489Ser is probably related to a mild biochemical phenotype; and p.Asp222Asn variant is probably not deleterious. The p.Asp444His variant seems to code for a protein with variable activity.

Novel mutations causing biotinidase deficiency in individuals identified by the newborn screening program in Minas Gerais, Brazil.

Biotinidase deficiency is an autosomal recessive inherited metabolic disorder caused by mutations in the BTD gene. Clinical manifestations can be treated and effectively prevented with pharmacological doses of biotin. Nine novel mutations in BTD are reported in 14 children diagnosed by the newborn screening program in Minas Gerais, Brazil, from June 2013 to December 2017. Serum BTD enzyme activity was determined for all cases and some parents. Two of the mutations are deletions and seven missense mutations located in the exonic region of the BTD gene, mostly in exon 4. Two newborns were profoundly biotinidase-deficient (one homozygous p.A534V [c.1601C > T] and another, double heterozygous for a novel mutation p.R211S [c.631C > A] co-inherited with an already described mutation p.T532 M [c.1595C > T]). Two mutations were associated with a partial deficiency of biotinidase (p.F361 V [c.1081 T > G] in two homozygous children, and p.S311 T [c.932G > C] in a compound heterozygous child who co-inherited a known severe mutation p.Y438X [c.1314 T > A]). The remaining five mutations were found in compound heterozygous children. Hence, a definitive conclusion about the degree of biotinidase deficiency is not possible yet. These results emphasize the importance of sequencing the BTD gene as an important tool to gain a better understanding of the correlation between biochemical phenotype and genotype.

Biotin in metabolism, gene expression, and human disease.

Biotin is a water-soluble vitamin that belongs to the vitamin B complex and which is an essential nutrient of all living organisms from bacteria to man. In eukaryotic cells biotin functions as a prosthetic group of enzymes, collectively known as biotin-dependent carboxylases that catalyze key reactions in gluconeogenesis, fatty acid synthesis, and amino acid catabolism. Enzyme-bound biotin acts as a vector to transfer a carboxyl group between donor and acceptor molecules during carboxylation reactions. In recent years, evidence has mounted that biotin also regulates gene expression through a mechanism beyond its role as a prosthetic group of carboxylases. These activities may offer a mechanistic background to a developing literature on the action of biotin in neurological disorders. This review summarizes the role of biotin in activating carboxylases and proposed mechanisms associated with a role in gene expression and in ameliorating neurological disease.

Caracterização bioquímica e genética da deficiência de biotinidase no Programa de Triagem Neonatal de Minas Gerais: estudo prospectivo de cinco anos / Biochemical and genetic characterization of biotinidase deficiency in the Neonatal Screening Program of Minas Gerais: a five-year prospective study

A deficiência da biotinidase (DB) é doença metabólica hereditária, autossômica recessiva, causada por mutações no gene da biotinidase (BTD), localizado no cromossomo 3. Apresenta expressão fenotípica diversa em razão de deficiência variável da atividade da enzima biotinidase. Se não diagnosticada precocemente, pode causar retardo mental e até morte. O tratamento preventivo é simples e de baixo custo, consistindo na ingestão de doses farmacológicas de biotina livre durante toda a vida. Este é um estudo populacional para confirmar a incidência da DB profunda e parcial em recém-nascidos (RN) triados pelo PTN-MG, estabelecer a frequência das variantes identificadas no BTD, estimar a frequência da variante p.D444H na população triada e correlacionar os níveis de atividade enzimática da biotinidase com o genótipo. Todos os testes bioquímicos e moleculares foram realizados nos laboratórios do Nupad-UFMG. Durante os 5 anos de estudo foram triados 1.168.385 RN e 634 apresentaram resultados alterados para triagem em papel filtro. Em 620 RN foi determinada a atividade sérica da biotinidase, sendo confirmados 84 RN com DB (6 com DB profunda e 78 com DB parcial) e 52 RN considerados suspeitos de terem a doença. A incidência combinada da DB foi de 1:13.909 (IC95% - 1:11.235 a 1:17.217). O sequenciamento de BTD nos 136 RN identificou 36 mutações, sendo 9 ainda sem registro em banco de dados. As variantes mais frequentes foram a p.D444H, p.[A171T;D444H], p.D543E, intrônica (c.310-15delT), p.V199M e p.H485Q. A frequência do alelo p.D444H foi estimada em 0,016 e a de indivíduos heterozigotos, 0,031. Observou-se que nem sempre a correlação fenótipo bioquímico e genótipo é consistente dada a variabilidade da atividade enzimática tanto entre pacientes com o mesmo genótipo quanto no mesmo paciente em dosagens consecutivas. Na grande maioria dos pacientes com DB parcial identificou-se a dupla heterozigose de p.D444H com outra variante, sendo observada um contínuo de valores entre 15% e 33% da atividade enzimática de referência. Quando a outra variante era sabidamente patogênica "grave", a variação sempre ocorria dentro da faixa para DB parcial. Quando da segunda variante decorria defeito enzimático mais brando, os valores se aproximavam ou pouco ultrapassavam o ponto de corte superior para DB parcial. Conclui-se que a incidência combinada de DB em MG está entre as mais altas do mundo e que, portanto, a triagem neonatal cumpre papel crucial na identificação precoce da doença, propiciando tratamento preventivo dos sintomas e sequelas. A grande variabilidade genotípica observada nos pacientes reflete a origem multiétnica do estado. A determinação sérica da atividade enzimática é, sem dúvida, o teste mais importante para confirmação do diagnóstico da DB. O sequenciamento do gene BTD, principalmente nos casos com classificação bioquímica duvidosa, cumpre papel relevante na definição do status do paciente e da necessidade de suplementação de biotina. Este estudo demonstra que o programa de triagem neonatal para DB em Minas Gerais é viável, útil e provavelmente efetivo sob o ponto de vista econômico.

Biotinidase deficiency (BD) is an autosomal recessive metabolic disorder caused by mutations in the BTD gene, located on chromosome 3. Diverse phenotypic expression is due to variable deficiency of biotinidase enzyme activity. If not diagnosed early in life, BD may cause mental retardation and even death. Preventive treatment is simple and inexpensive, consisting of administration of free biotin at pharmacological doses throughout life. This is a population-based study aiming to confirm the incidence of profound and partial BD in newborns (NB) screened by the PTN-MG, to establish the frequency of mutations identified in BTD gene, to estimate the frequency of p.D444H variant in the screened population, and to correlate levels of biotinidase enzymatic activity with the genotype. All biochemical and molecular tests were performed at Nupad-UFMG laboratories. During the five-year study, 1,168,385 newborns were screened and 634 had abnormal results in the filter-paper screening. Serum biotinidase activity was determined in 620 newborns, and BD was confirmed in 84 NB (6 with profound and 78 with partial BD); 52 NB were suspected of having the disease (upper borderline range). The combined incidence of BD was 1:13,909 (95%CI; 1:11,235 to 1:17,217). BTD sequencing in the 136 NB identified 36 mutations, 9 of which had not yet been registered in a public database. The most frequent variants were p.D444H, p.[A171T;D444H], p.D543E, intronic (c.310-15delT), p.V199M and p.H485Q. The frequency of the p.D444H allele was estimated at 0.016 and for heterozygous individuals, 0.031. Biochemical phenotype and genotype correlation has not been always consistent given some variability of enzymatic activity both between patients with the same genotype and in the same patient in consecutive dosages. In the great majority of patients with partial BD, the double heterozygosis of p.D444H was identified with another variant, being observed a continuum of values between 15% and 33% of the reference enzymatic activity. When the other variant was known to be "severely" pathogenic, the variation always occurred within the range for partial BD. When the second variant was due to a milder enzyme defect, the values approached or slightly exceeded the upper cutoff point for partial BD. In conclusion, the combined incidence of BD in MG is among the highest in the world and, therefore, neonatal screening plays a crucial role in the early identification of the disease, providing preventive treatment of symptoms and avoiding sequelae. The large genotypic variability observed in patients reflects the multiethnic origin of the state of MG. The serum determination of enzymatic activity is undoubtedly the most important test to confirm the diagnosis of BD. The BTD gene sequencing, especially in cases with doubtful biochemical classification, plays a relevant role in defining patient status and the need for biotin supplementation. This study demonstrates that DB screening program is feasible, useful, and probably cost-effective in Minas Gerais.

Biotinidase deficiency: Genotype-biochemical phenotype association in Brazilian patients.

INTRODUCTION: The association between the BTD genotype and biochemical phenotype [profound biotinidase deficiency (BD), partial BD or heterozygous activity] is not always consistent. This study aimed to investigate the genotype-biochemical phenotype association in patients with low biotinidase activity. METHODS: All exons, the 5'UTR and the promoter of the BTD gene were sequenced in 72 Brazilian individuals who exhibited low biotinidase activity. For each patient, the expected biochemical phenotype based on the known genotype was compared with the observed biochemical phenotype. Additional non-genetic factors that could affect the biotinidase activity were also analysed. RESULTS: Most individuals were identified by neonatal screening (n = 66/72). When consecutive results for the same patient were compared, age, prematurity and neonatal jaundice appeared to affect the level of biotinidase activity. The biochemical phenotype at the time of the second blood collection changed in 11/22 patients compared to results from the first sample. Three novel variants were found: c.1337T>C (p.L446P), c.1466A>G (p.N489S) and c.962G>A (p.W321*). Some patients with the same genotype presented different biochemical phenotypes. The expected and observed biochemical phenotypes agreed in 68.5% of cases (concordant patients). The non-coding variants c.-183G>A, c.-315A>G and c.-514C>T were present in heterozygosis in 5/17 discordant patients. In addition, c.-183G>A and c.-514C>T were also present in 10/37 concordant patients. CONCLUSIONS: The variants found in the promoter region do not appear to have a strong impact on biotinidase activity. Since there is a disparity between the BTD genotype and biochemical phenotype, and biotinidase activity may be affected by both genetic and non-genetic factors, we suggest that the diagnosis of BD should be based on more than one measurement of plasma biotinidase activity. DNA analysis can be of additional relevance to differentiate between partial BD and heterozygosity.

Thiamine Deprivation Produces a Liver ATP Deficit and Metabolic and Genomic Effects in Mice: Findings Are Parallel to Those of Biotin Deficiency and Have Implications for Energy Disorders.

Thiamine is one of several essential cofactors for ATP generation. Its deficiency, like in beriberi and in the Wernicke-Korsakoff syndrome, has been studied for many decades. However, its mechanism of action is still not completely understood at the cellular and molecular levels. Since it acts as a coenzyme for dehydrogenases of pyruvate, branched-chain keto acids, and ketoglutarate, its nutritional privation is partly a phenocopy of inborn errors of metabolism, among them maple syrup urine disease. In the present paper, we report metabolic and genomic findings in mice deprived of thiamine. They are similar to the ones we have previously found in biotin deficiency, another ATP generation cofactor. Here we show that thiamine deficiency substantially reduced the energy state in the liver and activated the energy sensor AMP-activated kinase. With this vitamin deficiency, several metabolic parameters changed: blood glucose was diminished and serum lactate was increased, but insulin, triglycerides, and cholesterol, as well as liver glycogen, were reduced. These results indicate a severe change in the energy status of the whole organism. Our findings were associated with modified hepatic levels of the mRNAs of several carbon metabolism genes: a reduction of transcripts for liver glucokinase and fatty acid synthase and augmentation of those for carnitine palmitoyl transferase 1 and phosphoenolpyruvate carboxykinase as markers for glycolysis, fatty acid synthesis, beta-oxidation, and gluconeogenesis, respectively. Glucose tolerance was initially increased, suggesting augmented insulin sensitivity, as we had found in biotin deficiency; however, in the case of thiamine, it was diminished from the 3rd week on, when the deficient animals became undernourished, and paralleled the changes in AKT and mTOR, 2 main proteins in the insulin signaling pathway. Since many of the metabolic and gene expression effects on mice deprived of thiamine are similar to those in biotin deficiency, it may be that they result from a more general impairment of oxidative phosphorylation due to a shortage of ATP generation cofactors. These findings may be relevant to energy-related disorders, among them several inborn errors of metabolism, as well as common energy disorders like obesity, diabetes, and neurodegenerative illnesses.

Deficiencia de biotinidasa y malformación de anillo vascular: reporte de un caso / Biotinidase deficiency and vascular ring malformation: case report

La deficiencia de biotinidasa es una alteración metabólica autosómica recesiva, que afecta la escisión de biotina disminuyendo su reciclado. Estudios en familiares del caso índice encontraron que generalmente ambos padres son portadores y los hermanos presentan el gen alterado; solo los homocigotos tienen síntomas que varían según el grado de deficiencia. Las madres pueden tener deficiencia moderada y mantenerse asintomáticas. En un estudio que utiliza células humanas expuestas a deficiencia de biotina, disminuyó el crecimiento celular y contribuyó al desarrollo de paladar hendido. La deficiencia de biotina en embarazadas ocasiona malformaciones en los productos. En recién nacidos, la deficiencia de biotinidasa se ha relacionado con síndrome VACTERL y páncreas anular. Se presenta el caso de una lactante con deficiencia de biotinidasa y defecto congénito de anillo vascular que rodea y comprime tráquea y esófago, alterando la deglución y la respiración. La niña fue suplementada con biotina e intervenida, con excelentes resultados.

Biotinidase deficiency is an autosomal recessive metabolic disorder that affects the cleavage of biotin. Family studies of the index case found that both parents are usually carriers and siblings have the altered gene, but only homozygotes have manifestations that vary depending on the deficiency grade. Mothers may have moderate deficiency and be asymptomatic; biotin deficiency in pregnant women causes defects in children. In a study, using human cells exposed to biotin deficiency, cell growth decreased contributing to the development of cleft palate. In newborns, biotinidase deficiency has been associated with VACTERL syndrome and annular pancreas. The case of an infant with biotinidase deficiency and congenital defect of the vascular ring is presented. This defect surrounds and compresses the trachea and esophagus, disturbing swallowing and breathing. Infant was supplemented with biotin and surgically intervened with excellent results.

Biotinidase deficiency: clinical and genetic studies of 38 Brazilian patients.

BACKGROUND: Biotinidase deficiency (BD) is an inborn error of metabolism in which some genetic variants correlate with the level of enzyme activity. Biotinidase activity, however, may be artifactually low due to enzyme lability, premature birth, and jaundice; this hinders both phenotypic classification and the decision to implement therapy. This study sought to characterize the clinical and genetic profile of a sample of Brazilian patients exhibiting reduced biotinidase activity. METHODS: This observational, multicenter study used a convenience sampling strategy, with sequencing of exons 2, 3, and 4 of the BTD gene. RESULTS: The sample comprised 38 individuals with biochemical phenotypes defined a priori on the basis of biotinidase activity in serum/plasma (2 with profound deficiency, 9 with partial deficiency, 15 heterozygous, 1 borderline between partial deficiency and heterozygosity, 2 borderline between heterozygous and normal) or dried blood spot sample (n = 9, all with unspecified deficiency). Most patients were from Southern Brazil (n = 29/38) and were identified by neonatal screening (n = 33/38). Parental consanguinity was reported in two cases. The most commonly found genetic variants were c.1330G > C (p.D444H), c.755A > G (p.D252G), and c.[511G > A;1330G > C] (p.[A171T;D444H]), with allele frequencies of 50%, 9.4%, and 5.4% respectively. Three novel pathogenic variants were identified (c.119 T > C or p.L40P, c.479G > A or p.C160Y, and c.664G > A or p.D222N). Twenty-nine patients had two pathogenic variants detected (with cis/trans status ascertained in 26/29), six had only one variant, and three had no pathogenic variants detected. Genotyping confirmed the original phenotypic classification based on enzyme activity in 16/26 cases. Three polymorphic variants were identified in control individuals, of which two were nonpathogenic (c.1171C > T or p.P391S and c.1413 T > C or p.C471C, with a frequency of 1.5% and 5.5% respectively) and one pathogenic (c.1330G > C, frequency 4%). CONCLUSIONS: Our findings suggest that partial BD is the most common form of BD in Brazil, and expand current knowledge on the allelic heterogeneity of this condition.

[Biotinidase deficiency and vascular ring malformation: case report]. / Deficiencia de biotinidasa y malformación de anillo vascular: reporte de un caso.

Biotinidase deficiency is an autosomal recessive metabolic disorder that affects the cleavage of biotin. Family studies of the index case found that both parents are usually carriers and siblings have the altered gene, but only homozygotes have manifestations that vary depending on the deficiency grade. Mothers may have moderate deficiency and be asymptomatic; biotin deficiency in pregnant women causes defects in children. In a study, using human cells exposed to biotin deficiency, cell growth decreased contributing to the development of cleft palate. In newborns, biotinidase deficiency has been associated with VACTERL syndrome and annular pancreas. The case of an infant with biotinidase deficiency and congenital defect of the vascular ring is presented. This defect surrounds and compresses the trachea and esophagus, disturbing swallowing and breathing. Infant was supplemented with biotin and surgically intervened with excellent results.

Deficiencia de la actividad de biotinidasa en la población de recién nacidos del Hospital Materno Infantil Ramón Sardá / Deficiency biotinidase activity in the newborn population of Maternity Hospital Ramón Sardá

La deficiencia de biotinidasa es una enfermedad autosómica recesiva del metabolismo provocado por la ausencia o deficiencia de esta enzima. Clínicamente se caracteriza por síntomas neurológicos: convulsiones, ataxia, pérdida de la audición, atrofia óptica retardo del desarrollo, alopecia, problemas dermatológicos y alteraciones metabólicas (acidemia orgánica cuya descompensación puede llevar al coma o a la muerte). La importancia de tener un método cuantitativo en suero o plasma es importante para confirmar esta patología. Objetivo: Obtener valores de referencia de actividad de biotinidasa en la población de recién nacidos (RN) en una maternidad pública aplicando un método colorimétrico para la cuantificación de la enzima en suero. Material y métodos: Se obtuvieron muestras de pesquisa neonatal y sueros de una población de 238 RN. La actividad de la biotinidasa fue determinada utilizando un método colorimétrico (a partir de una modificación del kit Umtest Biotinidasa de Tecnosuma). Los valores de referencia obtenidos en nuestra población fueron compatibles con los hallados en la bibliografía. La población patológica testigo presentó valores concordantes con su clasificación diagnóstica.

Biotinidase’s Deficiency is an autosomal recessive disorder of metabolism caused by the absence or deficiency of the enzyme. The clinical setting characterizes for neurological (convulsions, ataxia, auditive loss, optic atrophy, development delay), alopecia, skin rash and metabolic alterations (organic acidemia whose decompensation can produce coma or death). The availability of a quantitative technique in blood serum is vital to confirm this pathology. Objective: To obtain reference values for a population of newborns at Public Maternity applying a colorimetric quantitative method in serum blood. Material and methods: Dried blood samples and sera were obtained from a population of 238 newborns. The activity of Biotinidase was measured by using a colorimetric method (from a modification of the Umtest Bionitidase kit of Tecnosuma). We obtained reference values in the analysed population, which are compatible with the bibliographic values used until now. The control pathological population had results according to its diagnostic classification.

Biotina para o tratamento da deficiência de biotinidase / Biotin for the treatment of biotinidase deficiency

A deficiência de biotinidase é um erro inato do metabolismo, de herança autossômica recessiva. Na deficiência de biotinidase, a biotina não pode ser liberada a partir de pequenos biotinilpeptídeos e da biocitina. Assim, pacientes com esta deficiência são incapazes de reciclar a biotina endógena ou de usar a biotina ligada às proteínas da dieta, conseqüentemente a biotina é perdida na urina. Os pacientes com deficiência de biotinidase apresentam uma grande variabilidade de manifestações clínicas da doença, bem como na idade de apresentação dos sintomas. O quadro clínico completo já foi relatado a partir de 7 semanas de vida, mas sintomas neurológicos mais discretos podem ocorrer mais cedo, ainda no período neonatal; no entanto, algumas crianças podem não desenvolver sintomas até a adolescência. As manifestações neurológicas como hipotonia muscular, letargia, crises convulsivas mioclônicas e ataxia são os sinais clínicos iniciais mais freqüentes. Com base no nível da atividade de biotinidase, os pacientes são classificados em três grupos principais: 1. Pacientes com deficiência de biotinidase profunda: possuem menos de 10% da média atividade sérica normal de biotinidase. 2. Pacientes com deficiência de biotinidase parcial: com 10-30% da média atividade sérica normal de biotinidase. 3. Pacientes com diminuição da afinidade da biotinidase pela biocitina: esses pacientes tem atividade enzimática normal aos testes, usualmente realizados; mas a testagem com substratos mais específicos evidencia a diminuição de afinididade. A TECNOLOGIA: Biotina - A biotina (ou vitamina H) é um composto pertencente ao grupo de vitaminas hidrossolúveis do complexo B, necessária em diversas funções metabólicas. EVIDÊNCIAS CIENTÍFICAS: Além da análise dos estudos apresentados pelo demandante, a Secretaria-Executiva da CONITEC realizou busca na literatura por artigos publicados até o dia 01/05/2012. Busca na base de dados Medline/Pubmed(26): utilizando-se os termos "Biotinidase deficiency" [Mesh] e "Therapeutics" [Mesh], restringindo-se para estudos em humanos, identificou-se 9 estudos. Quando se utilizou os termos "Biotinidase deficiency" [Mesh] e "Treatment" [Mesh], restringindo-se para estudos em humanos, identificou-se 138 estudos. Busca na base de dados Embase(27): utilizando-se os termos "Biotinidase deficiency" e "Treatment", restringindo-se para estudos em humanos, identificou-se 155 estudos. Busca na base de dados Cochrane(28): utilizando-se o termo "Biotinidase deficiency", foram identificados 3 trabalhos: uma revisão sistemática sobre triagem neonatal de erros inatos do metabolismo, um estudo de custo-utilidade sobre estratégias de triagem neonatal, uma avaliação econômica sobre programas de triagem neonatal sistemática. Nenhuma metánalise sobre tratamento de Deficiência de Biotinidase foi identificada. Foram encontrados apenas relatos e série de casos, portanto nenhuma revisão sistemática ou ensaio clínico randomizado (ECR), que seriam as melhores evidências para avaliar a eficácia de uma tecnologia usada para tratamento. Foram revisados todos os artigos clínicos em língua inglesa, espanhola e portuguesa, sem restrição de data, que se referissem à abordagem terapêutica da Deficiência de Biotinidase em humanos (independente do sexo e idade). DELIBERAÇÃO FINAL: Os membros da CONITEC presentes na 1ª reunião extraordinária do dia 04/07/2012, por unanimidade, ratificaram a deliberação de recomendar a incorporação da Biotina para o Tratamento da Deficiência de Biotinidase, conforme Protocolo Clínico e Diretrizes Terapêuticas do Ministério da Saúde. DECISÃO: PORTARIA SCTIE/MS N° 34, de 27 de setembro de 2012 - Torna pública a decisão de incorporar o medicamento Biotina para o Tratamento da Deficiência de Biotinidase no Sistema Único de Saúde (SUS).

[The importance of a law on time: presentation of a girl with biotinidase deficiency who was not picked up through the neonatal screening]. / La importancia de una ley a tiempo: presentación de un caso de deficiencia de biotinidasa no diagnosticado por pesquisa neonatal.

In August 2008, the province of Buenos Aires had not adhered to the National law number 26279, that establishes the obligatory nature of the neonatal screening for biotinidase deficiency, among other diseases. In that date, a girl was born in Buenos Aires. She was admitted in the Hospital "J. P. Garrahan" with lethargy, metabolic acidosis, hiperlactacidemia, alopecia, conjuntivitis and scaly erythematous eruption in trunk, at 58 days of life, from a pediatric intensive care unit. Due to this clinic (13 days of evolution), a biotinidase assay in serum was done. This was abnormally low. She initiates treatment with biotin and the biochemical abnormalities revert quickly. If the neonatal screening had been done, this girl wouldn't have been exposed at risk of death, and a normal development would have been assure (by the presymptomatic beginning of the treatment), since the neurological injuries not always go back ad integrum.

La importancia de una ley a tiempo: Presentación de un caso de deficiencia de biotinidasa no diagnosticado por pesquisa neonatal / The importance of a law on time: presentation of a girl with biotinidase deficiency who was not picked up through the neonatal screening

En agosto de 2008, la Provincia de Buenos Aires no había adherido a la Ley Nacional 26279, que establece la obligatoriedad de la pesquisa neonatal para la deficiencia de biotinidasa, entre otras enfermedades. En esa fecha, nace en la Provinciade Buenos Aires una niña que derivan desde una terapia intensiva pediátrica al Hospital Nacional de Pediatría Dr. Prof. J. P. Garrahan, a los 58 días de vida, por alteración del sensorio, acidosis metabólica, hiperlacticoacidemia, alopecia, conjuntivitis y erupción cutánea eritematosa escaldada. Por estaclínica (de 13 días de evolución) se mide la actividad plasmática de biotinidasa, que resultó baja. Se inicia tratamiento con biotina y revierten rápidamente las alteraciones bioquímicas que presentaba. Si se hubiera hecho la pesquisa neonatal, estaniña no hubiera estado expuesta a riesgo de muerte por la enfermedad y se hubiese asegurado (por el inicio presintomático del tratamiento), un desarrollo normal, ya que las lesiones neurológicas no siempre retrogradan o no lo hacen ad integrum.