Regula Baumgartner

Maternal vegan diet causing a serious infantile neurological disorder due to vitamin B12 deficiency.

We present a 9-month-old exclusively breastfed baby of a strict vegetarian mother who had excluded all animal proteins from her diet. The patients symptoms included dystrophy, weakness, muscular atrophy, loss of tendon reflexes, psychomotor regression and haematological abnormalities. Biochemical investigations revealed severe methylmalonic aciduria and homocystinuria in the patient, slight methylmalonic aciduria in the mother and low concentrations of serum vitamin B12 in both patient and mother.

Isolated biotin-resistant deficiency of 3-methylcrotonyl-CoA carboxylase presenting as a clinically severe form in a newborn with fatal outcome

SummaryThe son of Kurdish, consanguineous parents (cousin marriage) presented from the first day of life with inititally focal and later generalized attacks of epileptic seizures and a severe generalized muscular hypotonia. Urinary excretion of 3-hydroxyisovalerate and of 3-methylcrotonylglycine was persistently increased. Diagnosis of isolated biotin-resistant 3-methylcrotonyl-CoA carboxylase deficiency was confirmed in cultured fibroblasts. Psychomotor retardation was progressive, seizures and marked EEG abnormalities persisted. Treatment with leucine and protein-resistricted diet under hospital control did not significantly improve these conditions. The patient died from a cardiac and circulatory failure after a prolonged epileptic attack, with bronchial aspiration. The non-responsiveness of our patient to therapy and the fatal outcome indicate the existence of a severe neonatal variant of this otherwise rather benign genetic enzyme deficiency.

Five patients with a biotin-responsive defect in holocarboxylase formation : Evaluation of responsiveness to biotin therapy in vivo and comparative biochemical studies in vitro

Biochemical studies in five patients with a defect in biotin-responsive holocarboxylase synthesis are reported. The age of onset (2 d to 6 y) as well as the severity of illness varied considerably. In all patients diagnosis was established by the finding of organic aciduria typical for multiple carboxylase deficiency in a catabolic state. In four patients the response to biotin therapy was evaluated by measurement of mitochondrial carboxylase activities in lymphocytes and by monitoring urinary organic acid excretion. In three patients clinical symptoms disappeared with 10-20 mg biotin/d, whereas normalization of the biochemical parameters required higher doses (20-40 mg/d). The fourth patient required a dose of 100 mg biotin/d before her skin rash disappeared. She remains mentally retarded and shows slightly elevated urinary organic acid excretion. Carboxylase activities were clearly deficient in fibroblasts grown in the commonly used medium which contains 10 nmol/L biotin (contributed by FCS in medium) in two patients. Fibroblasts of the other three patients became deficient only in a low biotin medium (0.1 nmol/L). Reactivation of deficient carboxylase activities in relation to time and biotin concentration correlated well with the severity and age of onset of illness in four patients. In one patient, however, carboxylase reactivation followed a more complex pattern requiring the longest incubation time but only a moderately increased biotin concentration of 19 nmol/L compared with 3-5 nmol/L in normal cells and 34-4000 nmol/L in the other four patients. The results in the five patients are in accordance with a primary defect of holocarboxylase synthetase due to a decreased affinity for biotin, in one patient combined with a decreased Vmax.

Arg538 to Cys mutation in a CpG dinucleotide of the human biotinidase gene is the second most common cause of profound biotinidase deficiency in symptomatic children

Abstract Biotinidase deficiency is an autosomal recessively inherited disorder in the recycling of the vitamin biotin. The most common mutation that causes profound biotinidase deficiency in symptomatic individuals is a deletion/insertion (G98:d7i3) that occurs in exon B of the biotinidase gene. We now report the second most common mutation, a C-to-T substitution (position 1612) in a CpG dinucleotide in exon D of the biotinidase gene. This mutation results in the substitution of a cysteine for arginine538 (designated R538C) and was found in 10 of 30 symptomatic children with profound biotinidase deficiency, 5 of whom also have the G98:d7i3 mutation. This mutation was not found in DNA samples from 32 individuals with normal biotinidase activity, but was found in one individual with enzyme activity in the heterozygous range. This mutation was not detected in 371 randomly selected, normal individuals using allele-specific oligonucleotide hybridization analysis. Aberrant biotinidase protein was not detectable in extracts of fibroblasts from a child who is homozygous for the R538C mutation, but was present in less than normal concentration in identical extracts treated with β-mercaptoethanol. Because there is no detectable biotinidase protein in sera of children who are homozygous for the R538C mutation and in combination with the deletion/insertion mutation, the R538C mutation likely results in inappropriate intra- or intermolecular disulfide bond formation, more rapid degradation of the aberrant enzyme, and failure to secrete the residual aberrant enzyme from the cells into blood.

Biotinidase deficiency: Clinical course and biochemical findings

The biotin responsive late-onset multiple carboxylase deficiency (McKusick 25327) has recently been shown to be due to biotinidase deficiency (EC 3.5.1.12; Wolfet al., 1983a). This affects the regeneration of biotin from biocytin so that biotin is not available for the mitochondrial carboxylases. In consequence the metabolism of propionylcoenzyme A, 3-methylcrotonylcoenzyme A and pyruvate is hampered. Symptoms which are considered to be characteristic of this condition are muscular hypotonia, ataxia, seizures, alopecia and seborrhoeic dermatitis. We report a case who presented only with exanthema and seizures during an acute febrile illness.

Molecular characterisation and neuropsychological outcome of 21 patients with profound biotinidase deficiency detected by newborn screening and family studies.

Early recognition by newborn screening and oral biotin supplementation may prevent clinical and neurological deficits in profound biotinidase deficiency (residual plasma biotinidase activity <10%). In order to evaluate possible correlations of molecular characteristics, onset and continuation of treatment and clinical outcome, we investigated 21 patients detected by newborn screening and consecutive family investigations. In 18 patients found by newborn screening, the range of biotinidase activities was 0%–9% residual activity. Application of a sensitive HPLC assay enabled us to discriminate five patients with residual biotinidase activities <1%. Two patients with zero activities were homozygous for the G98:d7i3 mutation and three patients with activities <1% carried mutations G98:d7i3, R157H, and Q456H. The mutation spectrum of the remaining patients included T532M, A171T+D444H, V62M,C432W, and D444H. Evaluation of clinical and neuropsychological outcome showed that only patients with biotinidase activities <1% exhibited characteristic clinical symptoms within the first weeks of life whereas five patients with residual activities of 1.2%–4.6% did not develop clinical symptoms even when not treated until 3.5–21 years. In all patients treated with biotin within the first weeks of life, neuropsychological outcome was normal whereas abnormal in three out of five patients tested for IQ and treated after the age of 3.5 years. Conclusion:the clinical and molecular spectrum of profound biotinidase deficiency is heterogeneous. Early onset of symptoms is predicted by the presence of zero residual activity as measured by sensitive assays and by homozygosity for the G98:d7i3 mutation. In patients with higher residual activities and variable mutational spectrum, correlation with the onset and severity of symptoms cannot be made.

Accumulation of odd-numbered long-chain fatty acids in fetuses and neonates with inherited disorders of propionate metabolism.

ABSTRACT: Fetuses affected with propionic acidemia incorporate great amounts of odd-numbered long-chain fatty acids (OLCFA) into their body lipids. This is due to abundant supply with precursor amino acids of propionyl-CoA throughout pregnancy. After birth, the lower provision of precursor amino acids during dietary treatment compared with fetal life results in a decline of propionyl-CoA production and therefore OLCFA synthesis. However, the observed decrease of OLCFA may also partly reflect the recovery from acute ketoacidotic episodes that the patients experienced soon after birth as long as they were undiag-nosed. In a patient with vitamin B-12-responsive methyl-malonic aciduria treated prenatally with large doses of vitamin B12 given to the mother, the cord plasma lipids contained normal amounts of OLCFA. This indicates that prenatal therapy led to an increased flux of propionyl-CoA through the defective methylmalonyl-CoA mutase step. Thus, in addition to the quantification of a decline in methylmalonic acid in maternal urine, OLCFA in cord blood lipids might be a further parameter for evaluating prenatal treatment in patients with vitamin B12-responsive methylmalonic aciduria.

Propionyl-CoA carboxylase deficiency with overflow of metabolites of isoleucine catabolism at all levels.

An 11-year old girl with spastic paraplegia and mental retardation has suffered from attacks of metabolic acidosis since the age of 18 months. “Ketotic hyperglycinemia” was diagnosed when she was 3 years old. Reinvestigation at 9 1/2 years included a two-day load with L-isoleucine, and propionyl-CoA carboxylase assay in cultured fibroblasts. The following compounds increased following the load: 3-hydroxypropionic acid, 2-methyl-3-hydroxybutyric acid, 2-ethylhydracrylic acid, 3-hydroxy-n-valeric acid, 3-oxo-n-valeric acid, 2-methyl-3-oxobutyric acid, 2-oxo-3-methylvaleric acid, 2-methyl-3-oxovaleric acid, N-tiglylglycine, methylcitric acid and butanone. Small amounts of alloisoleucine appeared in plasma. Propionyl-CoA carboxylase deficiency was suggested by this metabolite pattern and demonstrated in cultured fibroblasts.

Biotinidase deficiency: metabolites in CSF

The neonatal type of multiple carboxylase deficiency (McKusick 25327) is exclusively due to the holocarboxylase synthetase defect. The late onset form can also be due to this defect or to biotinidase deficiency (Burri et al., 1985; Wolf et al., 1985). After the neonatal period, these forms should be considered whenever unexplained symptoms (hypotonia, drug-resistant convulsions, developmental regression, respiratory distress, dermatitis, alopecia or lactic acidaemia) are found in conjunction with even minor abnormalities of propionate and leucine metabolites in the urine. L.L., a female, was noted as having developmental delay, hypotonia and tonic clonic seizures from the age of 7 months. At 23 months her skin appeared dry and pale and her hair was yellowish and brittle. She was unable to walk or sit. The EEG showed diffuse slowing and minimal diffuse convulsive activity. Arterial blood pH was 7.30. There was a minimal increase in 3-hydroxy-isovalerate and in 3-hydroxy-propionate to double the upper normal range in the urine, In CSF, lactate was 2.0 mmol L~ (normal < 1.2); propionate was 2.6/xmol L~ (normal <1.0); 2-hydroxy-butyrate was 0.1mmolL -1 and 3-hydroxy-isovalerate was 0.05 mmol L -1. In plasma, propionate was 6.7/xmol L -a (normal <1.8) but lactate was 1.3 mmol L -1 (normal). The activities of 3-methylcrotonyl-CoA carboxylase (EC 6.4.1.4) at 1.5%, pyrurate carboxylase (EC 6.4.1.1) at 3% and propionyl-CoA carboxylase (EC 6.4.1.3) at 13% of control were decreased in lymphocytes (Suormala et al., 1985). A biotinidase assay in plasma gave results of 0.07UL -~ in the patient, and 2.9 and 3 .4UL -~ in her parents (controls 5.6+0.9). With 10mgd -~ of biotin, the skin condition normalized and the neurological situation evidently improved. The EEG was normal. After four days of therapy carboxylase activities in lymphocytes were significantly increased. The plasma propionate levels were half the previous values. Since the predominant symptoms in this patient were developmental retardation, hypotonia and seizures with rather slight changes in skin and hair and only minor changes in leucine and isoleucine metabolites in the urine, we conclude in agreement with Wolf and colleagues (1985) that multiple carboxylase defects should be looked for even in the presence of unspecific neurological symptoms. However, the CSF examination is essential. For metabolite analyses, truly quantitative methods should be applied.

Proliferation and differentiation of cultured human follicular keratinocytes are not influenced by biotin

In humans and in animals, biotin deficiency causes pathological changes in the skin and its appendages. High doses of biotin may also have beneficial effects on skin, hair and fingernails in humans and animals with normal biotin status. Therefore, we investigated the effects of low and high concentrations of biotin on proliferation and differentiation of cultured outer root sheath cells from human hair follicles as an in vitro model for skin. The activities of biotin-dependent carboxylases were measured to evaluate the biotin status of the cells. In monolayer cultures of outer root sheath cells, proliferation and expression of the differentiation-specific keratins K1 and K10 were not influenced by extremely low concentrations of biotin (<2×10−10 mol/l) or by pharmacological doses of biotin (10−5 mol/l). Biotin deficiency of the cells was confirmed under the former condition by demonstrating decreased activities of the mitochondrial carboxylases. In organotypic cocultures of outer root sheath cells and dermal fibroblasts, in which stratified epithelia resembling epidermis were developed, the biotin concentration had no effect on the expression of all tested epidermal differentiation markers, including the suprabasal keratins K1 and K10, the hyperproliferation-associated keratin K16, involucrin and filaggrin.