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Histidinemia is a congenital metabolic disorder where the histidine (His) metabolism is blocked, resulting in increased concentrations of His in blood and urine. The disease causes an abnormal development of the patient's nervous system, which leads to many serious illnesses. Therefore, it is very important to diagnose early. In this study, we developed a novel fluorescent nanosensor NaGdF4:Yb3+, Er3+@SiO2–spiropyran (UCNP@SiO2–SP). The nanosensor displayed a “turn-off” fluorescence response towards His. When His was mixed with UCNP@SiO2–SP, His could specifically bind to SP, which could cause the isomerization of SP. The structure of SP was changed from spiroform into merocyanine form. The luminescence of the sensor was overlapped with the absorption of the merocyanine form. As a result, His will lead to fluorescence quenching of the sensor based on inner filter effects (IFE), which can be used to detect His. Importantly, as the first report of a UCNP@SiO2–SP nanosensor for detecting His, this method exhibits good selectivity and anti-interference capability. The detection limit is 4.4 μM. In addition, the amount of His in urine was also measured, suggesting the applicability of this sensor for histidinemia diagnosis.

Kinetics of the metabolism of the heterocyclic amino acid histidine exposed to the L-histidine ammonia-lyase enzyme has been investigated and the technology of extraction of histidine biotransformation products (urocanic acid and ammonia) from casein hydrolyzates enabling the subsequent use of these hydrolyzates as a milk protein concentrate for the production of specialized dietary products for the nutrition of histidinemia patients has been developed.

A new, precise, and very selective method for increasing the impact and assessment of histidine as a biomarker for early diagnosis of histidinemia disease in new born children was developed. The method depends on the formation of the ion pair associate between histidine and the nano optical samarium tetracycline [Sm-(TC)2]+ complex doped in sol-gel matrix in a borate buffer of pH 9.2. The [Sm-(TC)2]+ complex has +I net charge which is very selective and sensitive for [histidine]- at pH 9.2 in serum and urine samples of histidinemia disease. Histidine enhances the luminescence intensity of the nano optical [Sm-(TC)2]+ complex at 645nm after excitation at 400nm, in borate buffer, pH 9.2. The remarkable enhancement of the luminescence intensity at 645nm of nano [Sm-(TC)2]+ complex doped in sol-gel matrix by various concentrations of the histidine was successfully used as an optical probe for the assessment of histidine in different serum and urine samples of new born children infected by histidinemia. The calibration plot was achieved over the concentration range 1.4×10-5 - 6.5×10-10molL-1 histidine with a correlation coefficient of (0.998) and a detection limit of (3.2×10-10molL-1). The sensitivity (98.88%) and specificity (97.41%) of histidine as a biomarker were calculated.

Histidinemia is an inborn error of metabolism of amino acids caused by deficiency of histidase activity in liver and skin with consequent accumulation of histidine in plasma and tissues. Histidinemia is an autosomal recessive trait usually considered harmless to patients and their offspring, but some patients and children born from histidinemic mothers have mild neurologic alterations. Considering that histidinemia is one of the most frequently identified metabolic conditions, in the present study we investigated the effect of L-histidine load to female rats during pregnancy and lactation on some parameters of phosphoryltransfer network in cerebral cortex and hippocampus of the offspring. Pyruvate kinase, cytosolic and mitochondrial creatine kinase activities decreased in cerebral cortex and in hippocampus of rats at 21 days of age and this pattern remained in the cerebral cortex and in hippocampus at 60 days of age. Moreover, adenylate kinase activity was reduced in the cerebral cortex and in hippocampus of the offspring at 21 days of age, whereas the activity was increased in the two tissues at 60 days of age. These results suggest that administration of L-histidine to female rats in the course of pregnancy and lactation could impair energy homeostasis in the cerebral cortex and hippocampus of the offspring. Considering that histidinemia is usually a benign condition and little attention has been given to maternal histidinemia, it seems important to perform more studies in the children born from histidinemic mothers.

Histidinemia is an inherited metabolic disorder biochemically characterized by high concentrations of histidine in biological fluids. Usually affected patients are asymptomatic although some individuals have mental retardation and speech disorders. Considering the high prevalence of histidinemia and the scarce information on the effects of maternal histidinemia on their progeny, we investigated various parameters of oxidative stress in brain cortex and hippocampus of the offspring from female rats that received histidine (0.5 mg/g of body weight) in the course of pregnancy and lactation. At 21 days of age we found a significant increase of thiobarbituric acid reactive substances (TBARS), 20 ,70 -dihydrodichlorofluorescein oxidation, superoxide dismutase (SOD) activity, catalase (CAT) activity, total sulfhydryls and glutathione (GSH) content in cerebral cortex and hippocampus. We also verified that at 60 days of age, GSH, SOD and total sulfhydryls returned to normal levels in brain cortex, while the other parameters decreased in the same structure. In the hippocampus, at 60 days of age GSH returned to normal levels, CAT persisted elevated and the other parameters decreased. These results indicate that histidine administration to female rats can induce oxidative stress in the brain from the offspring, which partially recovers 40 days after breastfeeding stopped.

Flow injection method was developed for rapid, specific, and highly sensitive determination of histidine. The method is based on the fluorescence derivatization of histidine with orthophthalaldehyde in a carrier stream of neutral buffer. A linear calibration curve for histidine was obtained over the range of 0.02–1000 pmol per injection (10 μL) with the relative standard deviation of 0.58% at 1.0 pmol (n = 10) and with the detection limit (S/N = 8) of 15 fmol. Since the fluorescence derivatization is selective for histidine and the interfering substances are limited to glutathione and histamine, the flow injection method was applicable to the rapid and specific assay of histidine in deproteinized human serum, urine, and the extract of stratum corneum where the relative amounts of the interferents to histidine are considerably low. The present method can analyze forty samples per hour. Histidine values in the biological samples obtained by the present method correlated well with those determined by high-pe...

Although the exact prevalence of metabolic abnormalities in autism spectrum disorders is unknown, several metabolic defects have been associated with autistic symptoms. These include phenylketonuria, histidinemia, adenylosuccinate lyase deficiency, dihydropyrimidine dehydrogenase deficiency, 5'-nucleotidase superactivity, and phosphoribosylpyrophosphate synthetase deficiency. When the metabolic consequences of an enzyme defect are well defined (e.g., phenylketonuria, 5'-nucleotidase superactivity), treatment with diet, drugs, or nutritional supplements may bring about a dramatic reduction in autistic symptoms. This review evaluates evidence for metabolic etiologies in autism spectrum disorders, as well as for the efficacy of dietary and vitamin treatments. The relationship between gastrointestinal abnormalities and autism spectrum disorders is also considered.

Proprietary formulations of the amino acid L-histidine are under development as pharmaceutical agents because of the molecule's antioxidant and anti-inflammatory properties. L-histidine has been well characterized in terms of probable dietary requirements, plasma and tissue concentrations, pharmacokinetics, metabolism and excretion, and medical conditions related to physiologic handling. Previous experience with histidine dosing in the literature is extensive, and both clinical and preclinical data suggest that histidine administration is very safe. L-histidine has been shown to scavenge both the hydroxyl radical and singlet oxygen ( 1 0 2 ) in many studies. These interactions may involve free histidine, small histidine-containing peptides such as carnosine, and histidine residues in proteins. Histidine appears to interfere with redox reactions involving iron and perhaps other metal ions and to interact directly with 1 0 2 ; the ability of histidine to scavenge 1 0 2 , a toxic oxygen species of increasing concern, has been well established in the laboratory. Many recent studies have demonstrated the therapeutic efficacy of "pharmacologic" doses of L-histidine in animal models of inflammatory conditions, particularly gastrointestinal conditions and cardiac ischemia-reperfusion injury, and have specifically linked the anti-inflammatory capabilities of histidine to its ability to scavenge toxic oxygen species. The maintenance of histidine pools, therefore, may contribute to the body's physiologic antioxidant capacity. Taken together, the data suggest that histidine supplementation could provide a safe, efficacious method to increase antioxidant protection.

Speech disorders are a common the most common causes of the Logopedia and Phoniatry consultation during childhood, point at which the specialist perform the clinic functional examination to find the etiology in order to begin an effective rehabilitation treatment. The specific language impairment and speech are among the speech disorders of unknown cause. Histidinemia is frequently associated with speech disorders. An analytical case-control study was developed in 27 cases with speech disorders and 102 controls. The concentration of histidine in serum of all children was determined by an ultramicroanalytic method. The histidine levels were elevated in the 29.6% of the case group and only in the 1.0% of the control group. The histidine level difference is more significant among between the language impairment group and the control group, while children with dyslalia did not differ significantly with the children with specific language impairment and the control groups. These results showed that histidine levels are likely to be more elevated in children with speech disorders than in the control group. Los trastornos de la comunicación oral en el niño son causa frecuente de asistencia a la consulta de Logopedia y Foniatría, donde el especialista debe realizar el examen clínico funcional en busca de posible etiología para imponer el tratamiento rehabilitador. Dentro de estos trastornos se encuentran los trastornos específicos del lenguaje y del habla, donde no se conoce la causa. La histidinemia se asocia frecuentemente con trastornos de la comunicación oral. Se realizó un estudio analítico de casos y controles. Se estudiaron 27 niños con trastornos de la comunicación (casos) y 102 controles. A todos se les determinó los niveles de histidina en suero mediante un método ultramicroanalítico. Presentaron niveles elevados de histidina el 29,6% para los casos y en los controles solo el 1%, determinándose que la diferencia en los niveles de histidina es significativa entre los niños con TEL y los controles mientras que los niños con dislalia no se diferencian significativamente ni de los controles, ni de los niños con TEL. Los resultados obtenidos muestran que la probabilidad de encontrar concentraciones de histidina elevadas en los niños con trastornos de la comunicación oral es más alta que en el grupo control.

Los trastornos de la comunicación oral en el niño son causa frecuente de asistencia a la consulta de Logopedia y Foniatría, donde el especialista debe realizar el examen clínico funcional en busca de posible etiología para imponer el tratamiento rehabilitador. Dentro de estos trastornos se encuentran los trastornos específicos del lenguaje y del habla, donde no se conoce la causa. La histidinemia se asocia frecuentemente con trastornos de la comunicación oral. Se realizó un estudio analítico de casos y controles. Se estudiaron 27 niños con trastornos de la comunicación (casos) y 102 controles. A todos se les determinó los niveles de histidina en suero mediante un método ultramicroanalítico. Presentaron niveles elevados de histidina el 29,6% para los casos y en los controles solo el 1%, determinándose que la diferencia en los niveles de histidina es significativa entre los niños con TEL y los controles mientras que los niños con dislalia no se diferencian significativamente ni de los controles, ni de los niños con TEL. Los resultados obtenidos muestran que la probabilidad de encontrar concentraciones de histidina elevadas en los niños con trastornos de la comunicación oral es más alta que en el grupo control. Speech disorders are a common the most common causes of the Logopedia and Phoniatry consultation during childhood, point at which the specialist perform the clinic functional examination to find the etiology in order to begin an effective rehabilitation treatment. The specific language impairment and speech are among the speech disorders of unknown cause. Histidinemia is frequently associated with speech disorders. An analytical case-control study was developed in 27 cases with speech disorders and 102 controls. The concentration of histidine in serum of all children was determined by an ultramicroanalytic method. The histidine levels were elevated in the 29.6% of the case group and only in the 1.0% of the control group. The histidine level difference is more significant among between the language impairment group and the control group, while children with dyslalia did not differ significantly with the children with specific language impairment and the control groups. These results showed that histidine levels are likely to be more elevated in children with speech disorders than in the control group.

Histidase (EC 4.3.1.3) is a cytosolic enzyme that catalyzes the nonoxidative deamination of histidine to urocanic acid. Histidinemia, resulting from reduced histidase activity as reported in Cambridge stock his/his mice and in humans, is the most frequent inborn metabolic error in Japan. The histidase chromosomal gene (HAL) was isolated from a λEMBL-3 human genomic library using the human histidase cDNA as a probe. Restriction mapping and Southern blot analysis of the isolated clones reveal a single-copy gene spanning approximately 25 kb and consisting of 21 exons. Exon 1 encodes only 5′ untranslated sequence of liver histidase mRNA, with protein coding beginning in exon 2. A rarely observed 5′ GC, similar to that reported in the human P-450(SCC) gene, is present in intron 20. All other splicing junctions adhere to the canonical GT/AG rule. A TATA box sequence is located 25 bp upstream of the liver histidase transcription initiation site determined by S1 nuclease protection analysis. Several liver- and epidermis-specific transcription factor binding sites, including C/EBP, NFIL6, HNF5, AP2/KER1, MNF, and others, are also identified in the 5′ flanking region. Consistent with the hepatic and epidermal expression of histidase, this finding suggests that histidase transcription may be regulated by these factors. We further identify a polymorphism (A to G transition) in the histidase coding region of exon 16. The human histidase genomic structure presented here should facilitate the molecular investigation of symptomatic and asymptomatic forms of histidinemia.

A histidinemia é um erro inato do metabolismo de aminoácidos causado pela deficiência na atividade da enzima histidase no fígado e na pele, levando ao acúmulo de histidina no plasma e nos tecidos. É uma doença de caráter autossômico recessivo usualmente considerada inofensiva aos pacientes e a seus filhos; entretanto, alguns pacientes e crianças nascidas de mães histidinêmicas apresentam leves alterações neurológicas. Considerando que a histidinemia é uma das mais frequentes doenças metabólicas, no presente estudo nós investigamos o efeito da sobrecarga de L-histidina a ratas fêmeas durante a gestação e a lactação em alguns parâmetros do metabolismo energético em córtex cerebral e hipocampo da prole. As atividades da piruvatoquinase e da creatinaquinase citosólica e mitocondrial diminuíram em córtex cerebral e hipocampo dos ratos da prole aos 21 dias de idade e esse padrão permaneceu em ambas as estruturas aos 60 dias de idade. Além disso, a atividade da adenilatoquinase foi reduzida em córtex e hipocampo da prole aos 21 dias, enquanto a atividade aumentou nos dois tecidos aos 60 dias de vida. Estes resultados sugerem que a administração de L-histidina às ratas fêmeas no curso da gravidez e da amamentação prejudica a homeostasia energética em córtex cerebral e hipocampo dos ratos nascidos de mães tratadas. Considerando que a histidinemia é geralmente uma condição benigna e que pouca atenção tem sido dada à histidinemia materna, parece importante que mais estudos sejam realizados em crianças nascidas de mães histidinêmicas. Histidinemia is an inborn error of metabolism of amino acids caused by deficiency of histidase activity in liver and skin with consequent accumulation of histidine in plasma and tissues. Histidinemia is an autosomal recessive trait usually considered harmless to patients and their offspring, but some patients and children born from histidinemic mothers have mild neurologic alterations. Considering that histidinemia is one of the most frequently identified metabolic conditions, in the present study we investigated the effect of L-histidine load to female rats during pregnancy and lactation on some parameters of energy metabolism in cerebral cortex and hippocampus of the offspring. Pyruvate kinase, cytosolic and mitochondrial creatine kinase activities decreased in cerebral cortex and in hippocampus of rats at 21 days of age and this pattern remained in the cerebral cortex and in hippocampus at 60 days of age. Moreover, adenylate kinase activity was reduced in the cerebral cortex and in hippocampus of the offspring at 21 days of age, whereas the activity was increased in the two tissues at 60 days of age. These results suggest that administration of L-histidine to female rats in the course of pregnancy and lactation impaired energy homeostasis in the cerebral cortex and hippocampus of the offspring. Considering that histidinemia is usually a benign condition and little attention has been given to maternal histidinemia, it seems important to perform more studies in the children born from histidinemic mothers.

Microfluorometry for measuring phenylalanine, branched-chain amino acids, homocysteine and histidine in dried blood spots is presented as a new mass screening method for phenylketonuria, maple syrup urine disease, homocystinuria and histidinemia, respectively. Simple and rapid determinations of the metabolites are achieved by adapting each of the optimum fluorogenic reactions to a microplate scale followed by using a highly sensitive microplate reader. Each assay for several hundreds of samples can be completed within 3 h, with fully calculated results by an on-line microcomputer. The proposed system, both with simple procedure and quantitative results, is useful for the multiple routine screening for the four aminoacidopathies, in addition to galactosemia as we reported earlier [20]. (1) The usage of a microplate system for routine microplate screening might be able to open a new style of mass-screening. (2) Measurement of homocysteine seems to be more desirable than measuring methionine in order to detect classic homocystinuria, and to enable detection of the remethylatine defects. However, the recovery procedure of homocysteine needs to be improved; furthermore, the measuring of three branched-chain amino acids will be better than determining only leucine for detecting a mild form of maple syrup urine disease or other conditions which increase the levels of these amino acids. The manner in which we measure phenylalanine in our method is more sensitive than others using the microplate system.

The human gene for histidase (histidine ammonialyase; HAL), the enzyme deficient in histidinemia, was assigned to human chromosome 12 by Southern blot analysis of human × mouse somatic cell hybrid DNA. The gene was sublocalized to region 12q22→q24.1 by in situ hybridization, using a human histidase cDNA. The homologous locus in the mouse (Hal) was mapped to region 10C2→D1 by in situ hybridization, using a cell line from a mouse homozygous for a 1.10 Robertsonian translocation. These assignments extend the conserved syntenic region between human chromosome 12 and mouse chromosome 10 that includes the genes for phenylalanine hydroxylase, γ interferon, peptidase, and citrate synthase. The localization of histidase to mouse chromosome 10 suggests that the histidase regulatory locus (Hsd) and the histidinemia mutation (his), which are both known to be on chromosome 10, may be alleles of the histidase structural gene locus.

L-histidine ammonia-lyase (histidase) was encapsulated within cellulose nitrate artificial cells, and its kinetic parameters were evaluated. Microencapsulated histidase had an apparent activity of histidase in solution. Encapsulation did not alter the Km of histidase. The Km of histidase solution and the Km apparent of micro-encapsulated histidase were both 20 mM. Encapsulation of histidase resulted in increased stability of enzymatic activity at storage temperatures of 4 degrees C and 37 degrees C. At 37 degrees C histidase solution reached 50% of its original activity after 9.5 days of storage, while microencapsulated histidase reached the same level after 15 days. At 4 degrees C histidase solution had 63% of its original activity after 21 days of storage, while encapsulated histidase had 95%. In vitro experiments to evaluate the feasibility of microencapsulated histidase for possible experimental therapy in histidinemia were carried out. These experiments evaluated the effectiveness of encapsulated histidase in depleting histidine. Three different volume ratios of histidase loaded artificial cells to substrate solution were tested. A ratio of 1: 100 allowed 25% histidine depletion after 120 hours. A 1: 50 ratio allowed 35% histidine depletion after 72 hours. A 1: 25 ratio allowed 40% histidine depletion after 24 hours (Int J Artif Organs 1990; 13: 189-95).

Our results suggest that the association between the clinical diagnosis of schizophrenic disorder and heterozygosis for histidinemia is not a chance one. The real meaning of this relationship has to be further investigated.

Histidinemia is an inherited metabolic disorder caused by deficiency of histidase activity, which leads to tissue accumulation of histidine and its derivatives. Affected patients usually present with speech delay and mental retardation, although asymptomatic patients have been reported. Considering that the pathophysiology of the neurological dysfunction of histidinemia is not yet understood and since histidine has been considered a pro-oxidant agent, in the present study we investigated the effect of histidine and one of its derivatives, l -β-imidazolelactic acid, at concentrations ranging from 0.1 to 10 mM, on various parameters of oxidative stress in cerebral cortex of 30-day-old Wistar rats. Chemiluminescence, total radical-trapping antioxidant potential (TRAP), thiobarbituric acid reactive substances (TBA-RS), and the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were measured in tissue homogenates in the presence of l -histidine or l -β-imidazolelactic acid. We observed that l -histidine provoked an increase of chemiluminescence and a reduction of TRAP at concentrations of 2.5 mM and higher, while TBA-RS measurement, GSH-Px, CAT and SOD activities were not affected. Furthermore, l -β-imidazolelactic acid provoked antioxidant effects at high concentrations (5–10 mM) as observed by the reduction of chemiluminescence, although this compound enhanced chemiluminescence at low concentrations (0.5–1 mM). These results suggest that in vitro oxidative stress is elicited by histidine but only at supraphysiological concentrations.

The primary disorders of histidine metabolism are histidinemia and urocanase deficiency (urocanic aciduria).

We isolated overlapping cDNA clones encoding human histidase (histidine ammonia-lyase) from a human λgt10 library. The cDNA predicted a 657 amino acid protein of 72 651 Da. The human histidase amino acid sequence was 93% conserved with both rat and mouse histidase sequences, including four N -glycosylation consensus sites.

Neonatal screening for inborn errors of metabolism in Switzerland began in 1965 at the Children’s Hospital in Zurich with screening for phenylketonuria (PKU) by assaying for phenylalanine on dried spots of blood. In 1967, this screening was also initiated at the Central Laboratory of the Swiss Red Cross in Berne. The program then rapidly expanded. Screening for maple syrup disease (MSUD) by the Guthrie leucine assay, for homocystinuria by the Guthrie methionine assay, and for galactosemia with first the galactose assay (modified Guthrie test according to Paigen) and then for galactose-l-phosphate uridyltransferase activity (Beutler and Baluda) were added. Over the years some modifications of the program occurred: in 1973, the enzyme fluorimetric test according to Wiedemann that measures galactose was introduced in Berne for galactosemia screening and in 1974 TSH screening by RIA for congenital hypothyroidism (CH) was begun. In 1986, the enzyme immunoassay (Delfia) became the method for CH screening. Histidinemia screening with the Guthrie histidine assay was conducted as a pilot study for one year but a low prevalence, inadequate treatment and the large number of untreated cases described with normal development prompted abandonment of this screening. In 198 1 methionine screening was also abandoned, since no case of homocystinuria was identified during the 16 year screening period. However, four cases of hypermethioninemia, among them patients with fructose intolerance, were discovered with this screening. Biotinidase screening was added 1986. In 1987 leucine screening was also stopped, due to the low prevalance of MSUD and the fact that screening specimens collected on day 4 might be too late for the very early newborn diagnosis required in this

We describe here a procedure by capillary electrophoresis–mass spectrometry (CE–MS) for the direct analysis of urine samples on diagnostic metabolites, which are present in patient urine with metabolic disorders. The method was demonstrated using urine samples spiked with diagnostic metabolites, including glutathione for gamma-glutamyl transpeptidase deficiency, pyroglutamate for generalized glutathione deficiency, adenylosuccinate for adenylosuccinase deficiency, ornithine for gyrate atrophy, histidine for histidinemia, and homogentisic acid for alcaptonuria, at concentrations similar to those found in patients’ urine. A coaxial sheath liquid flow was used for coupling CE and MS in electrospray ionization mode. Identification of the metabolites is based on their molecular weights and fragmentation patterns. The CE–MS method is highly specific and sensitive comparing to the previously reported method using migration time and UV absorption for identification. It should find broad application in clinical and pharmaceutical research and development.

Histidase (histidine ammonia-lyase) is a cytosolic enzyme responsible for catalyzing the non-oxidative deamination of histidine to urocanic acid. Full-length cDNAs encoding rat histidase have been isolated from a lambdaZAP liver cDNA library using a partial cDNA fragment obtained by PCR. Whereas the initial description of the rat histidase 3' untranslated sequence contained a rare polyadenylation signal sequence, the data presented encompass a more distant 28-bp region, possessing a nucleotide stretch (AATATAAA), identical to that in the mouse histidase cDNA. Dideoxynucleotide chain-termination sequencing of two clones obtained by in vivo excision yielded an additional 376 bp and 105 bp of 5' and 3' untranslated sequences, respectively. A selected rat histidase cDNA clone was introduced into the pET-16b prokaryotic vector and expressed in BL21(DE3)pLysS Escherichia coli. After purification by nickel-chelation chromatography, recombinant histidine-tagged protein was employed to raise anti-(rat histidase) immunoglobulin in a Japanese white rabbit. The polyclonal rabbit antibody recognized and formed immune complexes with rat and recombinant human histidase proteins. Immunoblots of crude rat organ extracts detected a spectrum of histidase expression extending beyond that observed in liver and skin. Among other histidase-positive cells were those of the renal cortex tubular epithelium, fundic mucosal glands of stomach, gastric intramuscular (Auerbach's) plexus, and adrenal cortex. Immunohistochemical studies of histidase in rat liver produced discrete staining of hepatocytes in association with portal triads (Rappaport zone I). Furthermore, in contrast with previous reports of activity confined to epidermal stratum corneum, our findings demonstrate immunoreactive protein within and limited to the adjacent stratum granulosum.

Previous findings of increased heterozygosity for histidinemia among schizophrenic patients make the histidase gene a plausible candidate for genetic studies in schizophrenia. In the present study, we used a tetranucleotide repeat polymorphism in intron 8 of the histidase gene to examine the possibility that the histidase gene contributes to the genetic component of schizophrenia. In a first sample of 161 patients and 128 controls, we found the 4 repeat allele to be in excess in the patients. In contrast, the 3 repeat allele was less frequent in patients. A second sample of 95 patients and 93 controls was utilized to test these hypotheses. However, both observations were not replicated. We therefore concluded that our results do not support an involvement of the histidase gene in the development of schizophrenia.

Histidinemia (MIM235800) is characterized by elevated histidine in body fluids and decreased urocanic acid in blood and skin and results from histidase (histidine ammonia lyase, EC 4.3.1.3) deficiency. It is the most frequent inborn metabolic error in Japan. Although the original description included mental retardation and speech impairment, neonatal screening programs have identified the majority of histidinemic patients with normal intelligence. Molecular characteristics of histidase in histidinemia have not been determined, and cytogenetically visible deletions of 12q22-24.1 in which histidase gene resides have not been identified in histidinemic patients. In order to investigate whether individuals with this disorder have small deletions, additions, or point mutations in the histidase gene, we screened genomic DNA isolated from 50 histidinemic individuals who were discovered by the neonatal screening program. The methods employed included polymerase chain reaction (PCR) amplification of exons 1-21 of the histidase gene, followed by mutation detection enhancement gel electrophoresis and sequencing of the PCR products displaying heteroduplex bands. Four missense mutations (R322P, P259L, R206T, and R208L), two exonic polymorphisms (T141T c.423A--T and P259P c.777A--G), and two intronic polymorphisms (IVS6-5T--C and IVS9+25A--G) were identified. The frequencies of each polymorphism estimated either by dot blot allele-specific oligonucleotide hybridization, restriction enzyme digestion, or direct sequencing of the PCR products amplified from 50 unrelated normal individuals were 0.28, 0.30, 0.40, and less than 0.01, respectively. Mutation analysis of one family demonstrated that the patient inherited R322P from the mother and P259L from the father. This report describes the first mutations occurring in the coding region of the histidase structural gene in patients with histidinemia.

Histidinemia in mice and in humans is an autosomal recessive disorder of histidine metabolism that leads to high-histidine levels in both plasma and urine and is caused by a lack of hepatic histidine-alpha-deaminase (histidase). We have used a novel approach to hepatocellular transplantation to effect a complete phenotypic cure of histidinemia in a mouse model. Mice lacking histidase were treated with isolated liver cells (approximately 18 x 10(6) hepatocytes and 9 x 10(6) nonparenchymal cells) from histidase-competent donors transplanted into the peritoneum (active transplant group). Recipient mice showed a dramatic decrease, by more than 75%, in urinary histidine levels from day one throughout the course of the experiment, resulting in levels within the normal range for wild-type mice. In comparison, there was no change in urinary histidine levels in the control group of histidase-deficient mice treated with isolated liver cells from mice lacking histidase (statistical comparison between the two groups, P.003, two-way ANOVA). Histologically, ectopic liver tissue was seen in the peritoneum in association with abdominal wall, pancreas, and peritoneal connective tissue; immunohistochemical evidence showed expression of histidase in the ectopic liver tissue in the active transplant group. This report is the first to show complete correction of a defective biochemical phenotype achieved by hepatocellular transplantation.

Histidemia, first described by Ghadimi in 1961, is caused by a defect in histidase. The defect results in elevated urinary excretion of histidine and its transamination products, and in high blood histidine. Blood histidine levels in histidinemic patients range from 290 to 1420 microM (normal 70-120 microM). The clinical picture of histidinemia varies from complete normality to severe retardation, with many patients being asymptomatic. No correlation has been found between clinical and biochemical data. Most reported cases have been identified in newborn screening programs. Frequency of histidinemia ranges from 1 in 8000 (Japan) to 1 in 37,000 (Sweden). Histidinemia is inherited as an autosomal recessive trait. Maternal histidinemia is believed to be benign. Studies in animal models have shown similar metabolic changes in animals and humans, but clinical changes differ. Histidinemia may be treated with a low-histidine diet, which reduces elevated histidine levels, although in most cases no improvement of clinical symptoms has been observed.

We cloned a mouse histidase cDNA to identify the mutation in histidinemic mice (his/his) and to determine the relationship of the histidase locus (Hal) both to Chromosome 10 markers and to Hsd, the histidase activity variant locus. The his mutation, a G to A transition at nucleotide +965, changes Arg-322 to Gln (R322Q). Expression of the R322Q allele in COS cells resulted in proportionately reduced amounts of histidase protein and activity compared to the wildtype allele. Hal maps approximately 4 cM distal to the insulin-like growth factor-1 locus and approximately 10 cM proximal to steel. Hsd was found to be tightly linked to Hal, and the low-histidase-activity Hsd allele was associated with reduced histidase mRNA. These studies indicate that the R322Q allele reduces the stability of histidase, position Hal on the Chromosome 10 linkage map, and provide further evidence that Hsd is allelic to Hal.

A-7-year-old boy was found to have histidinuria without histidinemia. Low concentrations of histidine in plasma were consistent with impaired intestinal and renal tubular absorption of histidine. The patient was developmentally delayed and had some minor anomalies. Only 4 other patients in 3 families have been reported. Each had abnormality of the central nervous system. All were male.

Histidine has been reported to affect body zinc status by increasing urinary zinc excretion. The effects of experimental histidinemia on distribution of 65Zn in anesthetized rats were studied. Infusion of L-histidine at a rate sufficient to raise plasma concentrations to approximately 2 mM for 6 h starting 48 h after a single intraperitoneal 65Zn injection did not alter 65Zn activities in a variety of tissues when compared with anesthetized uninfused animals. However, plasma 65Zn and erythrocyte 65Zn were decreased, and liver 65Zn was increased. If 65Zn was injected intravenously during histidine infusion, net accumulation of zinc by some tissues was increased, but uptake by others was reduced relative to uninfused animals. In all cases, however, uptake expressed relative to plasma 65Zn levels was increased when allowance was made for the more rapid fall in plasma 65Zn during histidine infusion. Similar infusions of D-histidine produced quantitatively similar effects. Since enzymatic mechanisms and amino acid carriers would be expected to show stereoselectivity, such processes are unlikely to be involved in the zinc distribution changes described. The possibility of zinc transport by a hitherto unidentified carrier is discussed. These experiments confirm that histidinemia can affect zinc status, but any associated changes in urinary zinc excretion do not seem adequate to account for the tissue changes found.

Soon after Guthrie (1) expanded newborn screening by adding galactosemia, maple syrup urine disease (MSUD), and homocystinuria to the original screening for phenylketonuria (PKU), he realized that screening would be more efficient and comprehensive if a single assay could be used to detect several disorders rather than the system of a separate bacterial assay for each disorder that he had developed. He tried many ways to make such a single assay–using multiple inhibitors and different strains of bacteria–but nothing worked, so he abandoned the idea. Others had the same idea but used chromatography rather than bacterial assays (2)(3). Unfortunately, paper chromatography was insufficiently sensitive for screening newborn blood within the first days of life when the specimen is collected. To compensate for this shortcoming and to further expand the coverage of disorders, paper or thin-layer chromatography has been used for screening newborn urine (4). But here again, chromatography has had substantial disadvantages. First, an additional specimen is required because urine cannot replace blood in detecting either PKU or congenital hypothyroidism, the two indispensable disorders in screening. Second, the urine specimen must be collected by a parent or physician after nursery discharge, introducing a logistical problem. Third, urine varies widely in concentration, producing many false-positive results in the more highly concentrated specimens. This leads to otherwise unnecessary, anxiety-provoking requests for repeat specimens. Conversely, false-negative findings may result from dilute specimens. Finally, many of the disorders identified in urine, such as histidinemia, iminoglycinuria, and Hartnup disorder, are benign (4). Consequently, newborn urine screening based on chromatography has been discontinued in two of the three places in which was introduced, Australia (5) and Massachusetts, remaining only in Quebec (6). Thus, screening programs continue to rely on the “one test-one …

In 1991, the Ministry of Health & Social affairs adopted a nationwide service program for neonatal screening of phenylketonuria, galactosemia, maple syrup urine disease, homocystinuria, histidinemia & congenital hypothyroidism for newborns delivered from low class pregnant women registered in health centers. Government decreased the test items from six to two, PKU & congenital hypothyroidism to increase test numbers with same budget from 1995. Government decided to test PKU & hypothyroidism for all newborns from 1997. 78 laboratories wanted to participate for neonatal screening test in 1999. Government didn't decide laboratory center for a certain district and placed responsibility on free competition. Government are planning to test 573,000 newborns from 1998, Government decided to screen 6 items PKU, congenital hypothyroidism, maple syrup urine disese, homocystinuria, galactosemia and congenital adrenal hyperplasia from 2006. 17 laboratores are participating now. The cost of screening test is supported by both the federal government and local government on a 40-60 basis. In case a patient with an inherited metabolic disease is diagnosed by screening of government program, special milk is provided at government's expense. Interlaboratory quality control was started 6 times a year from 1994. According to the government project, 3,707,773 newborns were screened. 86 PKU, 718 congenital hypothyroidism were detected. So incidence of PKU is 1/43,114 and congenital hypothyroidism is 1/4,612. Maeil dairy company produced new special formula for PKU, MMA and PA, MSUD, urea cycle disorder, homocystinuria, isovaleric acidemia from Oct. 1999. The cost benefit of performing screening procedures coupled with treatment has been estimated to be as high as 1.77 times in PKU, 11.11 times in congenital hypothyroidism than cost without screening. We are trying to increase the budget to test all newborns for Tandem mass sereening & Wilson disease from 2008. Now it is a very important problem to decrease laboratory numbers of neonatal screening in Korea. So we are considering 4-5 central laboratories which cover all newborns and are equipped with tandem mass spectrometer & enzyme immunoassay for TSH, 17OHP & enzyme colorimetric assay for galactose

Histidinaemia is a relatively common inherited metabolic disorder with an incidence similar to phenylketonuria. This paper reports the long term outcome of patients diagnosed by newborn screening in the north west of England. Between 1966 and 1990, 108 infants were diagnosed as having histidinaemia by a regional neonatal screening programme (incidence 1:11,083). A further five children were detected following diagnosis in a sibling. Of the 113, nine were lost to follow up. Infants diagnosed before 1981 (n = 47) were placed on a low histidine diet (225 mg/kg/d) for an average period of 21 months (SD 4.5). All patients were reviewed regularly, Griffiths developmental quotients (DQ) were assessed at 2 and 4 years, and WISC-R intelligence quotients (IQ) at 8, 12, and 18 years. IQ data were converted to standard deviation scores (IQ SDS) to account for increasing IQ norms with time. Neither DQ nor IQ correlated with plasma histidine at diagnosis or with the mean plasma histidine throughout life. Growth was normal in all patients. There was no apparent benefit from a low histidine diet in early childhood. In contrast to other studies, there was no excess of clinical symptoms. On the basis of these findings, histidinaemia is a benign metabolic disorder that does not require treatment.