Chromosome 22q11.2 interstitial deletions among childhood-onset schizophrenics and "multidimensionally impaired".

Since its first description almost a century ago schizophrenia with childhood onset, a rare yet devastating disorder, has been diagnosed in children as young as age 5. Recently, the velocardiofacial syndrome, whose underlying cause is interstitial deletions of 22q11.2, was found in 2 of 100 cases of schizophrenics with adult onset [Karayiorgou et al., Proc Natl Acad Sci USA 92: 7612-7616, 1995]. No study has documented the prevalence of velocardiofacial syndrome and the 22q11.2 deletion in a population of schizophrenics with childhood onset. Here we describe the result of such a study in a sample originally selected for a trial of atypical antipsychotic drugs. A separate group of patients was also included in the study; they can best be accounted for as a variant of childhood-onset schizophrenia (COS) and had been provisionally termed "multidimensionally impaired." Fluorescent in situ hybridization screening of 32 COS and 21 multidimensionally impaired patients revealed 1 COS patient with an interstitial deletion spanning at least 2.5 megabases.

Childhood-onset schizophrenia/autistic disorder and t(1;7) reciprocal translocation: identification of a BAC contig spanning the translocation breakpoint at 7q21.

Childhood-onset schizophrenia (COS) is defined by the development of first psychotic symptoms by age 12. While recruiting patients with COS refractory to conventional treatments for a trial of atypical antipsychotic drugs, we discovered a unique case who has a familial t(1;7)(p22;q21) reciprocal translocation and onset of psychosis at age 9. The patient also has symptoms of autistic disorder, which are usually transient before the first psychotic episode among 40-50% of the childhood schizophrenics but has persisted in him even after the remission of psychosis. Cosegregating with the translocation, among the carriers in the family available for the study, are other significant psychopathologies, including alcohol/drug abuse, severe impulsivity, and paranoid personality and language delay. This case may provide a model for understanding the genetic basis of schizophrenia or autism. Here we report the progress toward characterization of genomic organization across the translocation breakpoint at 7q21. The polymorphic markers, D7S630/D7S492 and D7S2410/D7S646, immediately flanking the breakpoint, may be useful for further confirming the genetic linkage for schizophrenia or autism in this region. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:749-753, 2000. Published 2000 Wiley-Liss, Inc.

An analog of ACTH/MSH (4-9), ORG-2766, reduces cerebral uptake of morphine.

The uptake of morphine was significantly reduced in most regions of the brains of conscious, unrestrained rats within 10 minutes after treatment with an analog of ACTH/MSH (4-9), ORG-2766. The effect was most obvious in regions with significant densities of enkephalin receptors, namely basal ganglia, hippocampus and cortex. The results explain, in part, how some fragments and analogs of ACTH/MSH may antagonize behavioral actions of morphine, even though some of these peptides lack significant opiate receptor binding properties. We believe that this effect of ORG-2766 is related to an action on the permeability characteristics of the brain microvasculature. The underlying mechanism is unknown.

Velocardiofacial syndrome in childhood-onset schizophrenia.

OBJECTIVES: Deletion of chromosome 22q11 (velocardiofacial syndrome) is associated with early neurodevelopmental abnormalities and with schizophrenia in adults. The rate of 22q11 deletions was examined in a series of patients with childhood-onset schizophrenia (COS), in whom early premorbid developmental and cognitive impairments are more pronounced than in adult-onset cases. METHOD: Through extensive recruiting and screening, a cohort of 47 patients was enrolled in a comprehensive study of very-early-onset schizophrenia. All were tested with fluorescence in situ hybridization for deletions on chromosome 22q11. RESULTS: Three (6.4%) of 47 patients were found to have a 22q11 deletion. All 3 COS patients with 22q11 deletions had premorbid impairments of language, motor, and social development, although their physical characteristics varied. Brain magnetic resonance imaging revealed increased midbody corpus callosum area and ventricular volume in relation both to healthy controls and to other COS patients. CONCLUSIONS: The rate of 22q11 deletions in COS is higher than in the general population (0.025%, p < .001) and may be higher than reported for adult-onset schizophrenia (2.0%, p = .09). These results suggest that 22q11 deletions may be associated with an earlier age of onset of schizophrenia, possibly mediated by a more salient neurodevelopmental disruption.

Brief report: association of sex chromosome anomalies with childhood-onset psychotic disorders.

OBJECTIVE: An apparent excess of sex chromosome aneuploidies (XXY, XXX, and possibly XYY) has been reported in patients with adult-onset schizophrenia and with unspecified psychoses. This study describes the results of cytogenetic screening carried out for pediatric patients meeting DMS-III-R criteria for childhood-onset schizophrenia (COS) and a subgroup of patients with childhood-onset psychotic disorder not otherwise specified, provisionally labeled by the authors as multidimensionally impaired (MDI). METHOD: From August 1990 to July 1997, karyotypes were determined for 66 neuroleptic-nonresponsive pediatric patients (28 MDI, 38 COS), referred to the National Institute of Mental Health for an inpatient treatment trial of clozapine. RESULTS: Four (6.1%) of 66 patients (3 MDI, 1 COS) were found to have sex chromosome anomalies (mosaic 47,XXY; 47,XXY; 47,XYY; mosaic 45,XO, respectively), which is higher than the expected rate of 1 per 426 children or 2.34 per 1,000 in the general population (4/66 versus 1/426, chi 2 = 19.2, df = 1, p = .00001). All cases had been previously undiagnosed. CONCLUSIONS: These findings lend support to a hypothesis that a loss of balance of gene products on the sex chromosomes may predispose affected individuals to susceptibility to additional genetic and environmental insults that result in childhood-onset psychotic disorders. Karyotyping of children with psychotic disorders should be routine.

Neurologic course of congenital disorders of glycosylation.

Congenital disorders of glycosylation, formerly called carbohydrate-deficient glycoprotein syndrome, may present in infancy with slowly progressive neurologic deficits including cognitive impairment, ataxia, pigmentary retinal degeneration, and neuropathy. The metabolic defect is in N-linked oligosaccharide synthesis, and diagnosis is made by a serum transferrin isoelectric focusing. We reviewed the neurologic course of 10 children with congenital disorders of glycosylation (ages 13 months to 7 years). All had severe developmental delay and ataxia; none walked unassisted, and the highest level of communication was simple sign language in one patient. Five of 10 children had seizures (absence, complex partial, tonic clonic). Only one patient has had strokelike episodes, despite reports that they are common in this population. The underlying basis of these episodes has been hypothesized to be coagulopathy due to dysfunctional, incorrectly glycosylated coagulation factors. This 5-year-old patient with congenital disorders of glycosylation type Ia had two strokelike episodes, with evolving hemiparesis over 5 to 6 days' duration, followed by focal tonic-clonic seizures. Coagulation studies were normal. Electroencephalography showed transient hemispheric polymorphous delta-range slowing and suppression. Magnetic resonance imaging revealed corresponding cortical swelling. Magnetic resonance angiography was normal. Magnetic resonance spectroscopy revealed a decrease in the N-acetylaspartate peak, suggesting neuronal loss, with normal lactate peak. The neuroradiologic data do not support a thrombotic, embolic, or hemorrhagic basis for strokelike episodes in carbohydrate-deficient glycoprotein syndrome; other mechanisms must be considered.

Carbohydrate-deficient glycoprotein syndrome.

Carbohydrate-deficient glycoprotein syndrome consists of a group of disorders with multisystemic involvement and prominent neurologic symptoms. The full clinical spectrum continues to evolve, with four types currently recognized; type I is by far the most common. The clinical presentation of CDGS appears more severe in infants than in adults. Diagnosis is based on the clinical findings of characteristic fat distribution, neurologic impairment, and developmental delay, combined with the biochemical finding of cathodally migrating serum glycoproteins, transferrin in particular, on isoelectric focusing. Scientific evidence supports the hypothesis that abnormal synthesis of N-linked oligosaccharides is the basic metabolic defect in CDGS. The complex, multistep nature of the N-linked oligosaccharide pathway and the clinical heterogeneity of CDGS suggest that several different defects in the pathway can result in this disorder. Two specific enzyme defects have been reported: phosphomannomutase deficiency in some type I patients and N-acetylglucosamine transferase II deficiency in type II patients. Investigations continue into other metabolic bases of CDGS. The discovery of some of the enzyme defects paves the way for cloning, mutational analysis, and eventually prenatal diagnosis in appropriate families. No known treatment exists for CDGS; pallintive care and support is the most that can be offered. Family support systems are blossoming both in the United States and abroad, giving families the ability to communicate with each other and with workers in the field. As more cases are diagnosed and scientific research continues, advances in clinical definition, supportive care, nutrition, and prenatal diagnosis of CDGS are inevitable.

Genetic testing and screening in pediatric populations.

It is conceivable that in the near future a family could present themselves to their health care provider and request to be tested for diseases X, Y, and Z, equipped only with a web page listing of disease-causing genes. The testing of children suggests subtle and controversial inherent conflicts, however. Decisions about whether to provide genetic testing become increasingly murky for a health care professional as the requests advance from testing a child for carrier status for an autosomal recessive disorder, to testing a girl for a sex-linked mutation, to testing an asymptomatic child for a susceptibility to a particular disorder. Although no single case can exemplify every variable and circumstance confronting health care professionals today, this case-based discussion of x-linked severe combined immune deficiency can serve as a framework to examine some of the potential dilemmas surrounding the testing of children for genetic disorders.

Pulsed amperometric detection of carbohydrates in lysosomal storage disease fibroblasts: a new screening technique for carbohydrate storage diseases.

A first step in determining the metabolic defect in patients with an unknown storage disease is to identify the stored material. In the case of fibroblasts storing carbohydrates, this can be accomplished by trifluoroacetic acid (TFA) hydrolysis producing monosaccharides which are separated by anion-exchange chromatography and quantitated by pulsed amperometric detection. This technique separates neutral, amino, and acidic monosaccharides in a single run with a detection limit of 50 pmol. The method, applied to hydrolyzed 100,000 g supernatants of ten normal fibroblast sonicates, revealed a mean +/- S.D. content of the following monosaccharides (in nmol/mg of protein): fucose, 7 +/- 3; galactosamine, 4 +/- 2; glucosamine, 20 +/- 3; galactose, 11 +/- 3; mannose, 27 +/- 6; glucuronic acid, 56 +/- 28; iduronic acid, 17 +/- 11. Six mucopolysaccharidosis fibroblast strains (types I, II, IIIB, IVA, VI and VII) contained 2 to 8 times the normal glucuronic acid levels, and types I and II exhibited 10- to 30-fold normal levels of iduronic acid and 40-fold increases in galactosamine. All the mucopolysaccharidoses could be distinguished from normal based upon an increased concentration of some monosaccharide. Fibroblasts from patients with mannosidosis and fucosidosis contained 7-fold normal amounts of mannose and 11-fold normal amounts of fucose, respectively. The quantitation of monosaccharides in fibroblasts after TFA hydrolysis can identify cells that store excess amounts of a glycosaminoglycan, glycoprotein, oligosaccharide or, presumably, a glycolipid. This may comprise the first step toward identifying novel lysosomal storage disorders and point the way toward new glycoconjugate degradative pathways.

Phosphomannomutase activity in congenital disorders of glycosylation type Ia determined by direct analysis of the interconversion of mannose-1-phosphate to mannose-6-phosphate by high-pH anion-exchange chromatography with pulsed amperometric detection.

Congenital disorders of glycosylation (CDG) are a group of multisystemic disorders resulting from defects in the synthesis and processing of N-linked oligosaccharides. The most common form, CDG type Ia (CDG-Ia), results from a deficiency of the enzyme phosphomannomutase (PMM). PMM converts mannose 6-phosphate (man-6-P) to mannose-1-phosphate (man-1-P), which is required for the synthesis of GDP-mannose, a substrate for dolichol-linked oligosaccharide synthesis. The traditional assay for PMM, a coupled enzyme system based on the reduction of NADP(+) to NADPH using man-1-P as a substrate, has limitations in accuracy and reproducibility. Therefore, a more sensitive, direct test for PMM activity, based on the detection of the conversion of man-1-P to man-6-P by high-pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD), was developed. Using this assay, the activity of PMM was markedly deficient in fibroblasts and lymphoblasts from 23 patients with CDG-Ia (range 0-15.3% of control, average 4.9+/-4.7%) and also decreased in seven obligate heterozygotes (range 33.0-72.0% of control, average 52.2+/-14.7%). Unlike the spectrophotometric method, there was no overlap in PMM activity among patients, obligate heterozygotes, or controls. Thus, the PMM assay based on HPAEC-PAD has increased utility in the clinical setting, and can be used, together with transferrin isoelectric focusing, to diagnose patients with CDG-Ia and to identify heterozygotes when clinically indicated.

Localization of UDP glucuronosyltransferase gene(s) on mouse chromosome 5.

The drug-metabolizing UDP glucuronosyltransferases are encoded by genes which constitute a multigene family. One rat gene subfamily codes for at least four constitutive enzyme forms, including those which glucuronidate the androgenic steroids testosterone (UDPGTr-3) and androsterone (UDPGTr-4). In the present study, UDPGTr-3 and UDPGTr-4 cDNAs were used to demonstrate that an homologous subfamily is present in the mouse genome. Using mouse X Chinese hamster somatic cell hybrids, we mapped at least one gene of this UDP glucuronosyltransferase subfamily (UDPGTr-3) to mouse chromosome 5 and suggest the name as the Udpgt-3 locus.

Life-threatening splenic hemorrhage in two patients with Gaucher disease.

Massive splenomegaly is a frequent finding in patients with Gaucher disease, the most common of the sphingolipidoses. Even so, the risk for splenic rupture and intracapsular hemorrhage has not been emphasized due to the rarity of this occurrence and the fibrotic, rubbery consistency of splenic tissue in these patients. We report two adult patients with type 1 Gaucher disease who suffered life-threatening splenic bleeds that were not acutely diagnosed. Both patients ultimately required emergent splenectomies. Factors complicating the diagnosis of splenic hemorrhage in patients with Gaucher disease are discussed. Published 2000 Wiley-Liss, Inc.

Heterozygosity for an exon 12 splicing mutation and a W234G missense mutation in an American child with chronic tyrosinemia type 1.

Hereditary tyrosinemia type 1, an autosomal recessive disorder caused by deficiency of fumarylace-toacetate hydrolase (FAH), manifests in either an acute or a chronic form. We used reverse transcription and the polymerase chain reaction to amplify the FAH cDNA of a 12-year-old American boy with chronic tyrosinemia type 1. The patient is a compound heterozygote for mutations in the FAH gene. One allele contains a missense mutation in codon 234 changing a tryptophan to a glycine; this allele was of maternal origin. Mutagenesis and transfection into COS cells demonstrated that the W234G mutation abolishes FAH activity. The patient's paternally derived allele is a splicing mutation in the +5 position of intron 12, causing either insertion of a 105 bp fragment due to a cryptic splice site, or skipping of exon 12, or skipping of both exons 12 and 13. The chronic phenotype of tyrosinemia type 1 in this patient may be due to some residual, correct splicing by the allele with the splicing mutation.

Classic nephropathic cystinosis as an adult disease.

OBJECTIVE: To delineate the clinical characteristics of infantile nephropathic cystinosis in adult patients who have undergone renal transplantation. DESIGN: Case series. SETTING: Clinical research unit. PATIENTS: All 36 adult patients with nephropathic cystinosis referred to the National Institutes of Health. OUTCOME MEASURES: Longevity, growth, renal allograft survival, visual acuity, endocrine insufficiency, myopathy and swallowing dysfunction, cerebral calcifications, and occupational status. RESULTS: Of the 36 patients, seven were dead, five with functioning allografts. The 1-year and 5-year graft survival rates for 30 cadaveric allografts were 90% and 75%, respectively. The patients' mean height and weight were severely retarded. Five patients were legally blind, and three others had severely impaired vision in one eye. Thirty-one (86%) of 36 patients required thyroid hormone replacement therapy. One third had a distal myopathy, and 21 had moderate to severe swallowing abnormalities. Eight patients had cerebral calcifications on computed tomographic scan. Despite these complications, the sighted patients engaged in a normal variety of occupations. Only 11 patients were receiving adequate cystine-depleting therapy with cysteamine (mercaptamine) or phosphocysteamine. CONCLUSIONS: Adult patients with nephropathic cystinosis suffer serious complications of the disease.

Redox, transferrin-independent, and receptor-mediated endocytosis iron uptake systems in cultured human fibroblasts.

Sepharose beads bound to 55Fe-transferrin (Tf) were used to evaluate Tf-dependent iron uptake not employing receptor-mediated endocytosis (RME). The iron of 55Fe2-Tf-Sepharose was reduced and taken up by cultured human fibroblasts in a time- and concentration-dependent fashion (Km 7 microM; Vmax 128 pmol/mg/min). This redox system resembled that for Tf-independent iron uptake (Tf-IU, evaluated using 55Fe-citrate) in several ways. 1) NH4Cl did not inhibit iron uptake from 55Fe-citrate and 55Fe2-Tf-Sepharose but did inhibit uptake from 55Fe2-Tf (RME system). 2) Iron uptake and reduction from 55Fe2-Tf-Sepharose and 55Fe-citrate increased with temperature hyperbolically, differing from the sigmoidal curve for RME uptake. 3) The subcellular distributions of iron from 55Fe-citrate and 55Fe2-Tf-Sepharose resembled each other and differed from that for 55Fe2-Tf. 4) The optimal pH for iron reduction and uptake using 55Fe2-Tf-Sepharose or 55Fe-citrate was less than pH 5.5, while that for iron uptake from 55Fe2-Tf was pH 7.4. 5) The uptake and reduction of iron from 55Fe2-Tf-Sepharose was inhibited by ferric citrate and by transition metals. We conclude that both Tf-independent and non-RME, Tf-dependent iron uptake proceed via a common redox system for iron. The mechanisms of cellular iron uptake can be separately evaluated in fibroblasts using 55Fe-citrate, 55Fe2-Tf, and 55Fe2-Tf-Sepharose beads.

Clinical and biochemical studies in an American child with sialuria.

Sialuria is a rare inborn error of sialic acid (NeuAc) metabolism resulting from failure of CMP-NeuAc to adequately feedback inhibit the rate-limiting enzyme in sialic acid synthesis, UDP N-acetylglucosamine (UDP-GlcNAc) 2-epimerase. We describe the fourth reported sialuria patient, T.W., whose clinical features include developmental delay, coarse facies, and massive urinary excretion of sialic acid. Biochemical studies of T.W. fibroblasts revealed a 200-fold increase in free NeuAc content compared with normal. Bound NeuAc was only slightly elevated. The free NeuAc was predominantly in the cytosol fraction of fibroblasts after differential centrifugation, with only 4% of the free NeuAc content in other (nuclear, granular, and microsomal) cellular compartments. CMP-NeuAc inhibited UDP-GlcNAc 2-epimerase by 80% in normal fibroblasts but inhibited the epimerase of T.W. (sialuria) cells by only 13%. Cytidine feeding of sialuria fibroblasts decreased the intracellular free NeuAc content by 47%; this was accompanied by a fourfold increase in CMP-NeuAc, which may be sufficient to feedback inhibit the mutant epimerase and reduce free NeuAc production. Cytoplasmic pH was determined by the pH sensitive fluorescent indicator 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein, pentaacetoxymethylester (BCECF/AM) using the H+ equilibration method. The intracellular pH of sialuria fibroblasts, 7.18 +/- 0.04, was not found to be significantly different from that of normal cells (7.19 +/- 0.08).

Muscle carnitine repletion by long-term carnitine supplementation in nephropathic cystinosis.

The renal tubular Fanconi syndrome of children with nephropathic cystinosis causes plasma and muscle carnitine depletion. L-Carnitine replacement therapy for up to 18 mo has previously been shown to normalize plasma but not muscle carnitine levels. We treated six cystinosis patients, aged 1 to 4 y, with a mean dosage of 92 mg L-carnitine/kg/d given every 6 h for an average of 62 mo. Despite fractional excretions of free carnitine ranging from 55 to 108%, plasma-free and total carnitine concentrations were maintained at or above normal levels. At the end of the carnitine replacement period, the six children had muscle-free carnitine values ranging from 16.0 to 28.0 nmol/mg noncollagen protein compared with values of 3.0 to 11.4 for cystinosis children not supplemented with carnitine [normal, 22.7 +/- 5.0 (SD) nmol/mg protein]. Total muscle carnitine values were also normalized by L-carnitine replacement. The monthly increase in total body creatinine production, a measure of muscle mass, was higher (p = 0.036) in children with normal plasma free carnitine concentrations (3.4 +/- 0.9 mg/d) than in children with low plasma free carnitine (2.3 +/- 0.7 mg/d). No serious side effects, such as severe diarrhea, were observed. We conclude that oral L-carnitine replacement can normalize muscle carnitine content in children with cystinosis.

Abnormal synthesis of dolichol-linked oligosaccharides in carbohydrate-deficient glycoprotein syndrome.

Carbohydrate-deficient glycoprotein syndrome (CDGS) is a rare metabolic disorder presenting in infancy with severe neurologic involvement and variable multisystemic abnormalities. Diagnosis relies upon the detection of abnormal serum glycoprotein isoforms on isoelectric focusing (IEF) gels. Carbohydrate structural analyses were performed on the N-linked oligosaccharides of serum alpha 1-antitrypsin (alpha-1AT) from two Danish children with classical type I CDGS. Following preparative gel electrophoresis of alpha-1AT isoforms, oligosaccharide charge and monosaccharide composition analyses revealed increased glycosylation heterogeneity in CDGS compared with normal alpha-1AT. CDGS alpha-1AT isoforms bore N-glycans co-migrating with monosialylated standards, while normal alpha-1AT oligosaccharides co-migrated with both mono- and disialylated standards. While the monosaccharide contents of normal alpha-1AT isoforms were relatively uniform, those of CDGS alpha-1AT isoforms varied widely, and many were relatively mannose enriched. The mannose-rich oligosaccharides of CDGS alpha-1AT were not typical oligomannose structures since they were not released by endo-beta-N-acetylglucosaminidase H (endo H) digestion. Metabolic labelling of CDGS fibroblasts with [3H]mannose showed lower than normal intracellular total mannose, free mannose and phosphorylated mannose species, as well as diminished [3H]mannose incorporation into dolichol-linked and protein-linked oligosaccharides. In addition, the glycans liberated from CDGS dolichol-linked oligosaccharides were significantly truncated compared with those from normal fibroblasts. These data suggest that our type I CDGS patients produce abnormal N-linked oligosaccharides due to impaired biosynthesis of dolichol-oligosaccharide precursors.

Ophthalmologic examination in the diagnosis of Proteus syndrome.

PURPOSE: To describe the clinical features of Proteus syndrome, a rare recently recognized hamartoneoplastic malformation, with emphasis on the ocular findings. METHODS: Complete physical and ocular examination of two new patients with Proteus syndrome. RESULTS: The two reported cases illustrate the wide clinical polymorphism of Proteus syndrome and the overlap of its clinical manifestations with those of other overgrowth syndromes. Both patients had periorbital exostoses and epibulbar tumors. The ocular findings are compared with those in the literature. CONCLUSION: Considering the paucity of information in the ophthalmic literature, this article explores the role of the ophthalmologist in diagnosing this rare entity.