Functional disruption of pyrimidine nucleoside transporter CNT1 results in a novel inborn error of metabolism with high excretion of uridine and cytidine

Genetic defects in the pyrimidine nucleoside transporters of the CNT transporter family have not yet been reported. Metabolic investigations in a patient with infantile afebrile tonic-clonic seizures revealed increased urinary uridine and cytidine excretion. Segregation of this metabolic trait in the family showed the same biochemical phenotype in a healthy older brother of the index. Whole exome sequencing revealed biallelic mutations in SLC28A1 encoding the pyrimidine nucleoside transporter CNT1 in the index and his brother. Both parents and unaffected sibs showed the variant in heterozygous state. The transporter is expressed in the kidneys. Compelling evidence is available for the disrupting effect of the mutation on the transport function thus explaining the increased excretion of the pyrimidine nucleosides. The exome analysis also revealed a pathogenic mutation in PRRT2 in the index, explaining the epilepsy phenotype in infancy. At present, both the index (10 years) and his older brother are asymptomatic. Mutations in SLC28A1 cause a novel inborn error of metabolism that can be explained by the disrupted activity of the pyrimidine nucleoside transporter CNT1. This is the first report describing a defect in the family of CNT concentrative pyrimidine nucleoside transporter proteins encoded by the SLC28 gene family. In all likelihood, the epilepsy phenotype in the index is unrelated to the SLC28A1 defect, as this can be fully explained by the pathogenic PRRT2 variant. Clinical data on more patients are required to prove whether pathogenic mutations in SLC28A1 have any clinical consequences or are to be considered a benign metabolic phenotype.

Recognition of alpha-mannosidosis in paediatric and adult patients: Presentation of a diagnostic algorithm from an international working group

Alpha-mannosidosis is an ultra-rare progressive lysosomal storage disorder caused by deficiency of alpha-mannosidase. Timely diagnosis of the disease has the potential to influence patient outcomes as preventive therapies can be initiated at an early stage. However, no internationally-recognised algorithm is currently available for the diagnosis of the disease. With the aim of developing a diagnostic algorithm for alpha-mannosidosis an international panel of experts met to reach a consensus by applying the nominal group technique. Two proposals were developed for diagnostic algorithms of alpha-mannosidosis, one for patients ≤10 years of age and one for those >10 years of age. In younger patients, hearing impairment and/or speech delay are the cardinal symptoms that should prompt the clinician to look for additional symptoms that may provide further diagnostic clues. Older patients have different clinical presentations, and the presence of mental retardation and motor impairment progression and/or psychiatric manifestations should prompt the clinician to assess for other symptoms. In both younger and older patients, either additional metabolic monitoring or referral for testing is warranted upon suspicion of disease. Oligosaccharides in urine (historically performed) or serum were considered as an initial screening procedure, while enzymatic activity may also be considered as first choice in some centres. Molecular testing should be performed as a final confirmatory step. The developed algorithms can easily be applied in a variety of settings, and may help to favour early diagnosis of alpha mannosidosis and treatment.

Osteogenesis imperfecta and the teeth, eyes, and ears-a study of non-skeletal phenotypes in adults

Osteogenesis imperfecta (OI) is a disease causing bone fragility; however, it potentially affects all organs with a high content of collagen, including ears, teeth, and eyes. The study is cross-sectional and compares non-skeletal characteristics in adults with OI that clinicians should be aware of when caring for patients with OI.

INTRODUCTION

Osteogenesis imperfecta (OI) is a hereditary connective tissue disorder. The skeletal fragility is pronounced; however, OI leads to a number of extra-skeletal symptoms related to the ubiquity of collagen type 1 throughout the human body. The vast majority of knowledge is derived from studies performed in the pediatric population. Thus, we aimed to investigate the nature and prevalence of ophthalmologic, odontologic, and otologic phenotypes in an adult population with OI.

METHODS

The study population comprises 85 Danish OI patients (age 44.9 ± 15.9 years). Fifty-eight patients had OI type I, 12 OI type III, and 15 OI type IV according to the classification by Sillence. Audiometric evaluations and dental examinations were performed in 62 and 73 patients, respectively. Ophthalmologic investigations were performed in 64 patients, including measurements of the central corneal thickness.

RESULTS

All patients, except two, had corneal thickness below the normal reference value. Patients with OI type I and patients with a quantitative collagen defect had thinner corneas compared to patients with OI type III and other patients with a qualitative collagen defect. One patient in this cohort was diagnosed with and treated for acute glaucoma. Dentinogenesis imperfecta was diagnosed in one fourth of the patients, based on clinical and radiographic findings. This condition was predominately seen in patients with moderate to severe OI. Hearing loss requiring treatment was found in 15 of 62 patients, of whom three were untreated. The most prevalent type of hearing loss (HL) was sensorineural hearing loss, whereas conductive HL was solely seen in patients with OI type III. The patients with the most severe degrees of HL were patients with mild forms of OI. Age was associated with increased HL.

CONCLUSION

Although significant health problems outside the skeleton are frequent in adult patients with OI, the patients are not consistently monitored and treated for their symptoms. Clinicians treating adult patients with OI should be aware of non-skeletal health issues and consider including regular interdisciplinary check-ups in the management plan for adult OI patients.

Network reconstruction of the mouse secretory pathway applied on CHO cell transcriptome data

Background

Protein secretion is one of the most important processes in eukaryotes. It is based on a highly complex machinery involving numerous proteins in several cellular compartments. The elucidation of the cell biology of the secretory machinery is of great importance, as it drives protein expression for biopharmaceutical industry, a 140 billion USD global market. However, the complexity of secretory process is difficult to describe using a simple reductionist approach, and therefore a promising avenue is to employ the tools of systems biology.

Results

On the basis of manual curation of the literature on the yeast, human, and mouse secretory pathway, we have compiled a comprehensive catalogue of characterized proteins with functional annotation and their interconnectivity. Thus we have established the most elaborate reconstruction (RECON) of the functional secretion pathway network to date, counting 801 different components in mouse. By employing our mouse RECON to the CHO-K1 genome in a comparative genomic approach, we could reconstruct the protein secretory pathway of CHO cells counting 764 CHO components. This RECON furthermore facilitated the development of three alternative methods to study protein secretion through graphical visualizations of omics data. We have demonstrated the use of these methods to identify potential new and known targets for engineering improved growth and IgG production, as well as the general observation that CHO cells seem to have less strict transcriptional regulation of protein secretion than healthy mouse cells.

Conclusions

The RECON of the secretory pathway represents a strong tool for interpretation of data related to protein secretion as illustrated with transcriptomic data of Chinese Hamster Ovary (CHO) cells, the main platform for mammalian protein production.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-017-0414-4) contains supplementary material, which is available to authorized users.

A Consensus Genome-scale Reconstruction of Chinese Hamster Ovary Cell Metabolism

Chinese hamster ovary (CHO) cells dominate biotherapeutic protein production and are widely used in mammalian cell line engineering research. To elucidate metabolic bottlenecks in protein production and to guide cell engineering and bioprocess optimization, we reconstructed the metabolic pathways in CHO and associated them with >1,700 genes in the Cricetulus griseus genome. The genome-scale metabolic model based on this reconstruction, iCHO1766, and cell-line-specific models for CHO-K1, CHO-S, and CHO-DG44 cells provide the biochemical basis of growth and recombinant protein production. The models accurately predict growth phenotypes and known auxotrophies in CHO cells. With the models, we quantify the protein synthesis capacity of CHO cells and demonstrate that common bioprocess treatments, such as histone deacetylase inhibitors, inefficiently increase product yield. However, our simulations show that the metabolic resources in CHO are more than three times more efficiently utilized for growth or recombinant protein synthesis following targeted efforts to engineer the CHO secretory pathway. This model will further accelerate CHO cell engineering and help optimize bioprocesses.

Skeletal phenotypes in adult patients with osteogenesis imperfecta-correlations with COL1A1/COL1A2 genotype and collagen structure

Osteogenesis imperfecta (OI) is characterized by a high fracture rate and great heterogeneity. This cross-sectional study presents skeletal investigations and protein analyses in 85 adult OI patients. We find significant differences in bone mass, architecture, and fracture rate that correlate well with the underlying biochemical and molecular abnormalities.

INTRODUCTION

OI is a hereditary disease characterized by compromised connective tissue predominantly caused by mutations in collagen type 1 (COL-1) encoding genes. Widespread symptoms reflect the ubiquity of COL-1 throughout the body. The purpose of this study was to improve our understanding of clinical manifestations by investigating anthropometry and skeletal phenotypes (DXA, HRpQCT) in an adult OI population and compare the findings to underlying COL-1 genotype and structure.

METHODS

The study comprised 85 OI patients aged 45 (19-78) years, Sillence type I (n = 58), III (n = 12), and IV (n = 15). All patients underwent DXA, HRpQCT, spine X-ray, biochemical testing, and anthropometry. COL1A1 and COL1A2 were sequenced and 68 OI causing mutations identified (46 in COL1A1, 22 in COL1A2). Analysis of COL-1 structure (quantitative/qualitative defect) by SDS-PAGE was performed in a subset (n = 67).

RESULTS

A qualitative collagen defect predisposed to a more severe phenotype with reduced aBMD, more fractures, and affected anthropometry compared to patients with a quantitative COL-1 defect (p < 0.05). HRpQCT revealed significant differences between patients with OI type I and IV. Patients with type I had lower vBMD (p < 0.005), thinner cortexes (p < 0.001), and reduced trabecular number (p < 0.005) compared to patients with type IV indicating that HRpQCT may distinguish type I from type IV better than DXA.

CONCLUSION

The defective collagen in patients with OI has pronounced effects on the skeleton. The classical OI types based on the clinical classification show profound differences in bone mass and architecture and the differences correlate well with the underlying biochemical and molecular collagen abnormalities.

Cognitive profile and activities of daily living: 35 patients with alpha-mannosidosis

BACKGROUND

Alpha-mannosidosis (OMIM 248500) (AM) is a rare lysosomal storage disease caused by a deficiency of the alpha-mannosidase enzyme. The typical signs consist of hearing impairment, intellectual disabilities, coarse facial features and motor function disturbances. We report on the cognitive function and activities of daily living in patients with AM.

METHODS

Thirty five AM patients, age 6-35 years, were included in the study. As a cognitive function test, we used the Leiter international performance scale-revised (Leiter-R), which consists of two batteries: the visual function and reasoning battery and the memory and attention battery, the latter including a memory screening. Additional two questionnaires, The Childhood Health Assessment Questionnaire (CHAQ) and EQ-5D-5 L, were filled out.

RESULTS

We found IQ in the range of 30-81 in our cohort. The total equivalent age (mental age) was significantly reduced, between 3-9 years old for the visual function and reasoning battery, between 2.3-10.2 years for the memory screening. Data suggested a specific developmental profile for AM with a positive intellectual development until the chronological age 10-12 years, followed by a static or slightly increasing intellectual level. All patients were to varying degrees socially and practically dependent and unable to take care of themselves in daily life.

CONCLUSIONS

Intellectual disability is a consistent finding in patients with alpha-mannosidosis but with extensive variation. We assess that this group of patients has, despite their intellectual disabilities, a potential for continuous cognitive development, especially during childhood and early teenage years. This should be included and supported in the individual educational planning.

Alpha-mannosidosis: characterization of CNS pathology and correlation between CNS pathology and cognitive function

Alpha-mannosidosis (AM) (OMIM 248500) is a rare lysosomal storage disease. The understanding of the central nervous system (CNS) pathology is limited. This study is the first describing the CNS pathology and the correlation between the CNS pathology and intellectual disabilities in human AM. Thirty-four patients, aged 6-35 years, with AM were included. Data from 13 healthy controls were included in the analysis of the magnetic resonance spectroscopy (MRS). Measurements of CNS neurodegeneration biomarkers in cerebrospinal fluid (CSF), CSF-oligosaccharides, and performance of cerebral magnetic resonance imaging (MRI) and MRS were carried out. On MRI, 5 of 10 patients had occipital white matter (WM) signal abnormalities, and 6 of 10 patients had age-inappropriate myelination. MRS demonstrated significantly elevated mannose complex in gray matter and WM. We found elevated concentrations of tau-protein, glial fibrillary acidic protein and neurofilament light protein in 97 patients, 74% and 41% of CSF samples, respectively. A negative correlation between CSF-biomarkers and cognitive function and CSF-oligosaccharides and cognitive function was found. The combination of MRS/MRI changes, elevated concentrations of CSF-biomarkers and CSF-oligosaccharides suggests gliosis and reduced myelination, as part of the CNS pathology in AM. Our data demonstrate early neuropathological changes, which may be taken into consideration when planning initiation of treatment.

Carnitine levels in skeletal muscle, blood, and urine in patients with primary carnitine deficiency during intermission of L-carnitine supplementation

BACKGROUND

Primary carnitine deficiency (PCD) is a disorder of fatty acid oxidation with a high prevalence in the Faroe Islands. Only patients homozygous for the c.95A>G (p.N32S) mutation have displayed severe symptoms in the Faroese patient cohort. In this study, we investigated carnitine levels in skeletal muscle, plasma, and urine as well as renal elimination kinetics before and after intermission with L-carnitine in patients homozygous for c.95A>G.

METHODS

Five male patients homozygous for c.95A>G were included. Regular L-carnitine supplementation was stopped and the patients were observed during five days. Blood and urine were collected throughout the study. Skeletal muscle biopsies were obtained at 0, 48, and 96 h.

RESULTS

Mean skeletal muscle free carnitine before discontinuation of L-carnitine was low, 158 nmol/g (SD 47.4) or 5.4% of normal. Mean free carnitine in plasma (fC0) dropped from 38.7 (SD 20.4) to 6.3 (SD 1.7) μmol/L within 96 h (p < 0.05). Mean T 1/2 following oral supplementation was approximately 9 h. Renal reabsorption of filtered carnitine following oral supplementation was 23%. The level of mean free carnitine excreted in urine correlated (R (2) = 0.78, p < 0.01) with fC0 in plasma.

CONCLUSION

Patients homozygous for the c.95A>G mutation demonstrated limited skeletal muscle carnitine stores despite long-term high-dosage L-carnitine supplementation. Exacerbated renal excretion resulted in a short T 1/2 in plasma carnitine following the last oral dose of L-carnitine. Thus a treatment strategy of minimum three daily separate doses of L-carnitine is recommended, while intermission with L-carnitine treatment might prove detrimental.

A versatile system for USER cloning-based assembly of expression vectors for mammalian cell engineering

A new versatile mammalian vector system for protein production, cell biology analyses, and cell factory engineering was developed. The vector system applies the ligation-free uracil-excision based technique – USER cloning – to rapidly construct mammalian expression vectors of multiple DNA fragments and with maximum flexibility, both for choice of vector backbone and cargo. The vector system includes a set of basic vectors and a toolbox containing a multitude of DNA building blocks including promoters, terminators, selectable marker- and reporter genes, and sequences encoding an internal ribosome entry site, cellular localization signals and epitope- and purification tags. Building blocks in the toolbox can be easily combined as they contain defined and tested Flexible Assembly Sequence Tags, FASTs. USER cloning with FASTs allows rapid swaps of gene, promoter or selection marker in existing plasmids and simple construction of vectors encoding proteins, which are fused to fluorescence-, purification-, localization-, or epitope tags. The mammalian expression vector assembly platform currently allows for the assembly of up to seven fragments in a single cloning step with correct directionality and with a cloning efficiency above 90%. The functionality of basic vectors for FAST assembly was tested and validated by transient expression of fluorescent model proteins in CHO, U-2-OS and HEK293 cell lines. In this test, we included many of the most common vector elements for heterologous gene expression in mammalian cells, in addition the system is fully extendable by other users. The vector system is designed to facilitate high-throughput genome-scale studies of mammalian cells, such as the newly sequenced CHO cell lines, through the ability to rapidly generate high-fidelity assembly of customizable gene expression vectors.

X-linked congenital ptosis and associated intellectual disability, short stature, microcephaly, cleft palate, digital and genital abnormalities define novel Xq25q26 duplication syndrome

Submicroscopic duplications along the long arm of the X-chromosome with known phenotypic consequences are relatively rare events. The clinical features resulting from such duplications are various, though they often include intellectual disability, microcephaly, short stature, hypotonia, hypogonadism and feeding difficulties. Female carriers are often phenotypically normal or show a similar but milder phenotype, as in most cases the X-chromosome harbouring the duplication is subject to inactivation. Xq28, which includes MECP2 is the major locus for submicroscopic X-chromosome duplications, whereas duplications in Xq25 and Xq26 have been reported in only a few cases. Using genome-wide array platforms we identified overlapping interstitial Xq25q26 duplications ranging from 0.2 to 4.76 Mb in eight unrelated families with in total five affected males and seven affected females. All affected males shared a common phenotype with intrauterine- and postnatal growth retardation and feeding difficulties in childhood. Three had microcephaly and two out of five suffered from epilepsy. In addition, three males had a distinct facial appearance with congenital bilateral ptosis and large protruding ears and two of them showed a cleft palate. The affected females had various clinical symptoms similar to that of the males with congenital bilateral ptosis in three families as most remarkable feature. Comparison of the gene content of the individual duplications with the respective phenotypes suggested three critical regions with candidate genes (AIFM1, RAB33A, GPC3 and IGSF1) for the common phenotypes, including candidate loci for congenital bilateral ptosis, small head circumference, short stature, genital and digital defects.

Enzyme replacement therapy for alpha-mannosidosis: 12 months follow-up of a single centre, randomised, multiple dose study

BACKGROUND

Alpha-mannosidosis (OMIM 248500) is a rare lysosomal storage disease (LSD) caused by alpha-mannosidase deficiency. Manifestations include intellectual disabilities, facial characteristics and hearing impairment. A recombinant human alpha-mannosidase (rhLAMAN) has been developed for weekly intravenous enzyme replacement therapy (ERT). We present the preliminary data after 12 months of treatment.

METHODS

This is a phase I-II study to evaluate safety and efficacy of rhLAMAN. Ten patients (7-17 y) were treated. We investigated efficacy by testing motor function (6-minutes-Walk-Test (6-MWT), 3-min-Stair-Climb-Test (3-MSCT), The Bruininks-Oseretsky Test of Motor Proficiency (BOT2), cognitive function (Leiter-R), oligosaccharides in serum, urine and CSF and Tau- and GFA-protein in CSF.

RESULTS

Oligosaccharides: S-, U- and CSF-oligosaccharides decreased 88.6% (CI -92.0 -85.2, p < 0.001), 54.1% (CI -69.5- -38.7, p < 0,001), and 25.7% (CI -44.3- -7.1, p < 0.05), respectively. Biomarkers: CSF-Tau- and GFA-protein decreased 15%, p < 0.009) and 32.5, p < 0.001 respectively. Motor function: Improvements in 3MSCT (31 steps (CI 6.8-40.5, p < 0.01) and in 6MWT (60.4 m (CI -8.9 -51.1, NS) were achieved. Cognitive function: Improvement in the total Equivalence Age of 4 months (0.34) was achieved in the Leiter R test (CI -0.2-0.8, NS).

CONCLUSIONS

These data suggest that rhLAMAN may be an encouraging new treatment for patients with alpha-mannosidosis.The study is designed to continue for a total of 18 months. Longer-term follow-up of patients in this study and the future placebo-controlled phase 3 trial are needed to provide greater support for the findings in this study.

Patients with medium-chain acyl-coenzyme a dehydrogenase deficiency have impaired oxidation of fat during exercise but no effect of L-carnitine supplementation

BACKGROUND

It is not clear to what extent skeletal muscle is affected in patients with medium-chain acyl-coenzyme A dehydrogenase deficiency (MCADD). l-Carnitine is commonly used as a supplement in patients with MCADD, although its beneficial effect has not been verified.

DESIGN

We investigated (1) fuel utilization during prolonged low-intensity exercise in patients with MCADD and (2) the influence of 4 weeks of oral l-carnitine supplementation on fuel utilization during exercise.

METHODS

Four asymptomatic patients with MCADD and 11 untrained, healthy, age- and sex-matched control subjects were included. The subjects performed a 1-hour cycling test at a constant workload corresponding to 55% of Vo2max, while fat and carbohydrate metabolism was assessed, using the stable isotope technique and indirect calorimetry. The patients ingested 100 mg/kg/d of l-carnitine for 4 weeks, after which the cycling tests were repeated.

RESULTS

At rest, palmitate oxidation and total fatty acid oxidation (FAO) rates were similar in patients and healthy control subjects. During constant workload cycling, palmitate oxidation and FAO rates increased in both groups, but increased 2 times as much in healthy control subjects as in patients (P = .007). Palmitate oxidation and FAO rates were unchanged by the l-carnitine supplementation.

CONCLUSION

Our results indicate that patients with MCADD have an impaired ability to increase FAO during exercise but less so than that observed in patients with a number of other disorders of fat oxidation, which explains the milder skeletal muscle phenotype in MCADD. The use of carnitine supplementation in MCADD cannot be supported by the present findings.

Brain N-acetylaspartate levels correlate with motor function in metachromatic leukodystrophy

BACKGROUND

Late infantile metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal storage disorder that causes severe demyelination of the nervous system. The neuronal metabolite N-acetylaspartate (NAA) serves as a source of acetyl groups for myelin lipid synthesis in oligodendrocytes and is known as a marker for neuronal and axonal loss. NAA and other metabolite levels measured by proton magnetic resonance spectroscopy (MRS) correlate with performance of the brain in normal children. There is a need for sensitive measures of disease progression in patients with MLD to enable development of future treatments.

METHODS

A cross-section of 13 children with late infantile MLD were examined by proton MRS. Signals from NAA, total choline, and total creatine in the deep white matter were measured and correlated with the results of cognitive and motor function tests.

RESULTS

The NAA signal decreased as the disease process advanced. Motor function, measured by the Gross Motor Function Measure-88, varied from 13 (only head movement in the supine position) to 180 (able to walk) across the study cohort, demonstrating a wide range in functional status. Similarly, varied decreases were observed in cognitive function. We report strong positive correlations between standardized measures of motor and cognitive function and NAA levels in the deep white matter.

CONCLUSIONS

We suggest that NAA levels could serve as a sensitive biomarker in children with MLD. Proton MRS may provide a valuable tool for measuring the effects of treatment interventions in this disorder.

Highly variable clinical phenotype of carbamylphosphate synthetase 1 deficiency in one family: an effect of allelic variation in gene expression?

Deficiency of the urea cycle enzyme carbamylphosphate synthetase 1 (CPS1) causes hyperammonemia with a vast range of clinical severity from neonatal onset with early lethality to onset after age 40 with rare episodes of hyperammonemic confusion. The cause for this variability is not understood. We report two patients from one family with highly divergent clinical course, one presenting neonatally with a fatal form and the other at age 45 with benign diet-responsive disease. The patients are compound heterozygous for two mutations of the CPS1 gene, c.3558 + 1G > C and c.4101 + 2T > C. The haplotypes containing each mutation are identical between the two patients, as are the sequences of CPS1 exons and flanking introns. Transcriptional experiments show that the abnormal CPS1 transcripts generated by both mutations are identical in these two patients. We characterize promoter and enhancer sequences of the CPS1 gene and find also in these regions no sequence differences between patients. Finally, we perform cloning experiments and find that in the neonatal-onset case, clones of messenger RNA (mRNA) expressed from the allele carrying the c.4101 + 2T > C mutation are threefold more than clones of mRNA from the allele with the c.3558 + 1G > C mutation, whereas in the adult-onset case the two types of clones are equal, indicating skewed expression towards the c.4101 + 2T > C allele in the neonatal case. Although we are yet to understand the mechanism of this differential expression, our work suggests that allelic imbalance may explain clinical variability in CPS1 deficiency in some families.

Preserved fertility in a non-mosaic Klinefelter patient with a mutation in the fibroblast growth factor receptor 3 gene: Case Report

Patients with Klinefelter syndrome (47,XXY) are characterized by eunuchoid body proportions, gynaecomastia, small firm testes and azoospermia. We describe a Klinefelter patient (non-mosaic 47,XXY karyotype) who was heterozygous for the classical 1138G>A mutation in the fibroblast growth factor receptor 3 (FGFR3) gene, which is a gain-of-function mutation resulting in achondroplasia. The patient had phenotypic characteristics of achondroplasia (e.g. short limbed dwarfism and frontal bossing). Testicular volume was 8 ml at 27 years of age and repeated semen samples showed sperm concentrations of 0.175 million/ml. Serum FSH levels were elevated (21.7 IU/l) compared to normal age-matched healthy male controls and patients with non-mosaic Klinefelter syndrome, and inhibin B levels were low-normal, in contrast to the usually undetectable inhibin B levels in adult Klinefelter patients. The patient fathered a child from a spontaneous pregnancy. The observed testicular size and function in our patient contrast the typical findings in classical Klinefelter syndrome. We speculate that the alteration of FGFR3 protein function in our Klinefelter patient alleviated the destruction of the seminiferous tubules and may suggest that the fibroblast growth factor family has a pleiotrophic function in human spermatogonia, which physiologically express FGFR3.

Carnitine transporter and holocarboxylase synthetase deficiencies in The Faroe Islands

Carnitine transporter deficiency (CTD) and holocarboxylase synthetase deficiency (HLCSD) are frequent in The Faroe Islands compared to other areas, and treatment is available for both disorders. In order to evaluate the feasibility of neonatal screening in The Faroe Islands we studied detection in the neonatal period by tandem mass spectrometry, carrier frequencies, clinical manifestations, and effect of treatment of CTD and HLCSD. We found 11 patients with CTD from five families and 8 patients with HLCSD from five families. The natural history of both disorders varied extensively among patients, ranging from patients who presumably had died from their disease to asymptomatic individuals. All symptomatic patients responded favourably to supplementation with L: -carnitine (in case of CTD) or biotin (in case of HLCSD), but only if treated early. Estimates of carrier frequency of about 1:20 for both disorders indicate that some enzyme-deficient individuals remain undiagnosed. Prospective and retrospective tandem mass spectrometry (MS/MS) analyses of carnitines from neonatally obtained filter-paper dried blood-spot samples (DBSS) uncovered 8 of 10 individuals with CTD when using both C(0) and C(2) as markers (current algorithm) and 10 of 10 when using only C(0) as marker. MS/MS analysis uncovered 5 of 6 patient with HLCSD. This is the first study to report successful neonatal MS/MS analysis for the diagnosis of HLCSD. We conclude that CTD and HLCSD are relatively frequent in The Faroe Islands and are associated with variable clinical manifestations, and that diagnosis by neonatal screening followed by early therapy will secure a good outcome.

Xanthurenic aciduria due to a mutation in KYNU encoding kynureninase

Massive urinary excretion of xanthurenic acid, 3-hydroxykynurenine and kynurenine, known as xanthurenic aciduria or hydroxykynureninuria, in a young Somali boy suggested kynureninase deficiency. Mutation analysis of KYNU encoding kynureninase of the index case revealed homozygosity for a c.593 A > G substitution leading to a threonine-to-alanine (T198A) shift. A younger brother was found to have a similar excretion pattern and the same genotype. At present, neither of the two boys has symptoms of niacin deficiency. This is the first report linking xanthurenic aciduria to a mutation in the gene encoding kynureninase.

Molecular characterisation of six patients with prolidase deficiency: identification of the first small duplication in the prolidase gene and of a mutation generating symptomatic and asymptomatic outcomes within the same family

Prolidase deficiency (PD) is a rare autosomal recessive connective tissue disorder caused by mutations in the prolidase gene. The PD patients show a wide range of clinical outcomes characterised mainly by intractable skin ulcers, mental retardation and recurrent respiratory infections. Here we describe five different PEPD mutations in six European patients. We identified two new PEPD mutant alleles: a 13 bp duplication in exon 8, which is the first reported duplication in the prolidase gene and a point mutation resulting in a change in amino acid E412, a highly conserved residue among different species. The E412K substitution is responsible for the first reported phenotypic variability within a family with severe and asymptomatic outcomes.

On the neurotoxicity of glutaric, 3-hydroxyglutaric, andtrans-glutaconic acids in glutaric acidemia type 1

Glutaric acidemia type 1 (GA1) is an autosomal recessively inherited deficiency of glutaryl-CoA dehydrogenase. Accumulating metabolites, 3-hydroxyglutaric (3-OH-GA), glutaric (GA), and trans-glutaconic (TG) acids, have been proposed to be involved in the development of the striatal degeneration seen in children with GA1 via an excitotoxic mechanism. We have studied the extent to which 3-OH-GA, GA, and TG are neurotoxic and whether neurotoxicity is caused by an excitotoxic mechanism in which 3-OH-GA, GA, or TG overactivates N-methyl-D-aspartate (NMDA) receptors. In cultured mouse neocortical neurons, all three compounds were weakly neurotoxic, possibly through activation of NMDA receptors. However, further studies in the rat cortical wedge preparation and with NMDA receptors expressed in Xenopus oocytes could not confirm an interaction of the compounds with NMDA receptors. It is concluded that the metabolites 3-OH-GA, GA, and TG are only weak neurotoxins and that the neurodegenerative cascade destroying the striatum in patients with GA1 involves mainly mechanisms other than excitoxicity.

Cataract in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD)

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is a rare metabolic disorder that can lead to acute encephalopathy, liver disease, cardiomyopathy, rhabdomyolysis, and long-term complications involving the eye and peripheral nerves. LCHADD is a peroxisome biogenesis disorder (PBD). Except for the series presented by Tyni and colleagues (Ophthalmology 1998;105:810-824), which described visually insignificant lens opacities in association with LCHADD, previous ophthalmic papers have only reported retinal complications. We report on one case with progressive asymmetrical cataract. The more mildly affected eye had a similar morphology to that previously reported and the more severely affected eye had an unusual morphology we believe is unique to LCHADD. We discuss the range of ophthalmic presentations in our cases and in the literature. The variability of the severity of ocular complications, even between eyes in one individual, makes it difficult to test the effectiveness of therapeutic options upon the ophthalmic complications.

What is the role of medium-chain triglycerides in the management of long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency?

Cardiomyopathy is common in infants with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency. Resolution of the cardiomyopathy can often be achieved by avoidance of fasting and changing from a conventional infant formula to one in which most long-chain fat is replaced by medium-chain triglycerides (MCT). It is uncertain whether the clinical improvement is due to the restriction of long-chain fat or whether the MCT have specific beneficial effects. To clarify this, the metabolic effects of MCT were examined in 5 patients. When given at around the level found in MCT-based infant formula, MCT had no effect on blood concentrations of ketone bodies, specific fatty acids or acylcarnitines. The present study cannot, however, exclude the possibility that MCT per se may have beneficial effects.

Plasma and erythrocyte fatty acid concentrations in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency

Plasma and erythrocyte fatty acids have been measured in 9 patients with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency being treated with a low-fat diet. No significant abnormality was detected and in particular docosahexaenoic acid was not deficient.

Feeding difficulties in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency

Feeding difficulties are common in long chain 3-hydroxyacyl-CoA dehydrogenase deficiency in early childhood and are not associated with developmental disability, metabolic abnormalities, or the overnight feeding regimen. They are an inherent part of the phenotype and it is important to recognise them because of the distress and disruption they cause.

Osteogenesis imperfecta: mosaicism and refinement of the genotype-phenotype map in OI type III. Mutations in brief no. 242. Online

Non-lethal OI III (OMIM 259420) is caused by structural aberrations of collagen I. We report four novel glycine substitutions, one in the a1 (I) chain of collagen I (G688S) and three in the a2 (I) chain (G241D, G247C, G883V). In each of two families (G241D and G883V), we found parental mosaicism for the substitution explaining recurrence and intrafamilial variability of OI. The G247C and the G883V are the most N-terminally and C-terminally, respectively, placed cysteine and valine substitutions reported. The new substitutions add important information to the genotype-phenotype map and in particular the importance of a-chain stoichiometry is underlined. Data regarding the G688S substitution may suggest a different effect of the two a-chains in the development of dentinogenesis imperfecta (DI).

(G586V) substitutions in the alpha 1 and alpha 2 chains of collagen I: effect of alpha-chain stoichiometry on the phenotype of osteogenesis imperfecta?

Osteogenesis imperfecta (OI) is a congenital disease of connective tissue, most often caused by single amino acid substitutions of glycine residues within the triple helical region of collagen I. Collagen I consists of two alpha 1 chains and one alpha 2 chain. Thus, a substitution in the alpha 1(I) chain is thought to affect the function of the collagen molecule more than would a similar substitution in the alpha 2(I) chain, thereby causing more severe OI. Theoretically this hypothesis may be tested by comparing patients with identical substitutions in different alpha-chains. We present a Gly586Val substitution in the alpha 1(I) chain, and compare our findings to those resulting from Gly586Val substitutions in the alpha 2(I) chain (Forlino et al., 1994; Bateman et al., 1991). Our proband had lethal OI type II. Most alpha-chains of collagen I produced by his cultured fibroblasts were overmodified. The denaturation temperature of the abnormal collagen was 1.5 degrees C below normal. Cyanogen bromide cleavage and subsequent sequencing revealed a G-to-T base substitution at nucleotide 2420 of COL1A1, resulting in a Gly586Val substitution. The collagen findings were almost identical to those reported by Bateman et al. (1991) and Forlino et al. (1994), but the clinical phenotypes were different: the patients with the alpha 2(I) substitutions had OI type IV and III and not the lethal OI type II of our proband. It is known that identical biochemical aberrations in the same chain may have different phenotypic effects, both within families and between non-related patients. This must be taken into account in our cautious proposal that substitutions in the alpha 1(I) chain may have more serious consequences than similar substitutions in the alpha 2(I) chain.

Metabolism of some radiolabeled essential fatty acids in isolated rat hepatocytes is affected by dietary ethanol

The metabolism of the essential fatty acids [1-14C]20:4n-6, [1-14C]20:5n-3 and [1-14C]22:6n-3 was studied in rat hepatocytes fed ethanol in two different diets. Using a diet with a low lipid content ethanol (1) reduced the elongation of eicosapentaenoic acid, (2) reduced the esterification of docosahexaenoic acid (DHA) in phospholipids (PL), (3) increased the oxidation of DHA, (4) increased the ratio of esterification of DHA in phosphatidylethanolamine (PE) compared to phosphatidylcholine (PC) (PE/PC ratio), (5) altered the formation of PL molecular species, and (6) induced a decrease in the endogenous content of the hepatocytes of arachidonic acid and linoleic acid and an increase in oleic acid, 20:3n-9 and DHA. Using a high lipid diet, only the above-mentioned effect (4) was induced by ethanol, not the effects (1)-(3) and (5)-(6).

[Child abuse and osteogenesis imperfecta. How do we distinguish?]

Osteogenesis imperfecta is a hereditary connective tissue disorder. Typical manifestations are fragile bones with multiple bone fractures and bone deformities. A history of minimal or no trauma and recurrent fractures is a feature of OI, but is also typical of non-accidental injury (NAI). OI and NAI are relevant differential diagnoses when a child presents with unexplained fractures. The differential diagnostic problems are reviewed, all of which are important for the child both in terms of treatment and for prognosis, socially and medicolegally. We conclude that comprehensive clinical evaluation is adequate for differential diagnosis and that both OI and NAI can be diagnosed by positive anamnestic and objective signs. Mild OI IV without other signs than fracture(s) is very rare and the new entity temporary brittle bone disease is hypothetical; the diagnosis of these two clinical pictures is unacceptable in small children. Routine analysis of collagens should not be performed.

Bone mineral content and collagen defects in osteogenesis imperfecta

Whole-body and spine dual-energy X-ray absorptiometry was done in 63 patients with osteogenesis imperfecta aged 5 to 63 y, and the results were compared with OI types and collagen defects. Bone mineral content (BMC)-for-age, bone area (BA)-for-age, bone mineral density (BMD)-for-age, and BMC-for-BA were reduced, especially in patients with OI III/IV and/or in those with a qualitative collagen defect. BA-for-height was normal. Some patients with OI I and/or a quantitative collagen defect had BMD at or above -2 z-scores. We conclude (i) that both BMC and BMD differ significantly between OI types and collagen defects, (ii) that reduced BMC-for-age in OI patients is due mainly to reduced height ("short bones") and reduced BMC-for-BA ("light bones"), whereas BA-for-height ("bone width") is normal, (iii) that most OI patients have lower than average BMC, but in some mildly affected patients brittleness may exist with only small reductions in BMC.

Co-existence of osteogenesis imperfecta and hyperparathyroidism

Osteogenesis imperfecta (OI) and hyperparathyroidism (HTP) are disorders affecting the skeletal system and calcium metabolism not evidently related to one another. We report a case in which both OI and HPT were present. Our female patient presented with hypercalcaemia (S-Ca2+ 1.59 mmol/l; normal range 1.15-1.30) and 4-gland parathyroid hyperplasia at 30 years of age. Since her first year she had fractures, blue sclera, hypermobile joints, short stature (height 1.51 m, weight 49.5 kg) but normal hearing, and dentiogenesis imperfecta (tooth disease caused by defective formation of dentin) was absent. This patient bears many similarities with the 5 patients reported previously but it is the only patient, to our knowledge, with OI and early onset of HPT (30 year old female). We have found the OI to be type 1. A minor improvement of the rate of bone turnover 10 months after parathyroidectomy indicates the HPT to be primary and suggests the OI type 1 and pHPT to be two different calcium metabolic diseases incidentally occurring in the same patient.

Anthropometry of patients with osteogenesis imperfecta

Standing height, sitting height, armspan, subischial leg length, head circumference, and growth hormone-insulin-like growth factor I (IGF-I) axis were determined in 86 patients with osteogenesis imperfecta. The aim of this study was to determine standing height and body proportions and their variability among osteogenesis imperfecta types and collagen defects. Mean standing height was reduced in all groups of patients, to the greatest extent and variability in osteogenesis imperfecta type III/IV and in those with qualitative collagen defects. The mean standing height of patients with osteogenesis imperfecta was lower than that of their unaffected first degree family members. Truncal height of patients with osteogenesis imperfecta was reduced; head size was increased, and this was more pronounced in patients with osteogenesis imperfecta type III/IV and qualitative collagen defects than in patients with osteogenesis imperfecta type I and quantitative collagen defects. Mean concentrations of IGF-I and IGF binding protein 3 (IGFBP-3) were low, but most values were within age specific reference values. The reduction of standing height appears to correlate with osteogenesis imperfecta type and the type of collagen defect. A relatively short trunk is typical and head circumference and body length are disproportionate.

[Shaken baby syndrome]

Shaken baby syndrome is a serious form of physical child abuse, which is frequently overlooked. It should be suspected in all children younger than one year of age, who present with drowsiness, coma, seizures or apnoea. A combination of subdural haematomas and retinal haemorrhages with minimal or no trauma and no coagulopathy is almost pathognomonic of the syndrome. The findings are caused by shaking with or without impact. Physical signs of violence are often absent and the syndrome may easily be mistaken for serious infection or seizure disorder. Many cases are fatal or lead to severe disability including blindness, cerebral palsy, mental retardation or epilepsy in about 60% of the children. There are many unresolved problems regarding diagnosis, pathophysiology, treatment, prognosis, prophylaxis and legal actions. We discuss these problems and in addition present eleven children with shaken baby syndrome.

Collagen-derived markers of bone metabolism in osteogenesis imperfecta

Markers of bone formation [C-terminal and N-terminal propeptides of procollagen I (PICP, PINP), osteocalcin and alkaline phosphatase] and bone resorption [C-terminal cross-linked telopeptide of collagen I (ICTP) and hydroxypyridinium cross-links, pyridinoline (Pyr) and deoxypyridinoline (Dpyr)] were measured in 78 osteogenesis imperfecta (OI) patients to investigate bone metabolism in vivo and relate marker concentrations to phenotype and in vitro collagen I defects, as shown by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). PICP and PINP were generally low, and the serum levels were lower in all children and adults with mild OI and a quantitative collagen defect than in patients with severe OI and a qualitative collagen I defect. ICTP, Pyr and Dpyr were generally normal or reduced, but elevated in severely affected adults with a qualitative collagen I defect. The in vivo findings correlated with in vitro results of collagen I SDS-PAGE. Bone turnover is reduced in OI children and mildly affected OI adults, whereas bone resorption is elevated in severely affected adults. These findings may prove helpful for diagnosis and decision-making regarding therapy in OI.

Atraumatic loss of a kidney in a patient with alpha1-antitrypsin deficiency

Alpha1-Antitrypsin (alpha1AT) deficiency is characterized by a high risk of developing pulmonary emphysema and liver disease. Arteriopathy may be associated with alpha1AT deficiency. We present a patient with only one kidney and alpha1AT deficiency, but only mild pulmonary symptoms and no signs of liver disease, and atraumatic loss of the remaining kidney. Histological examination of the renal artery showed desposits of a mucoid ground substance in the arterial media, as has been demonstrated in other patients with alpha1AT deficiency. After dialysis treatment for 15 months, the patient underwent an uneventful kidney transplantation. The case draws attention to the awareness of complications of alpha1AT deficiency even in cases with only mild pulmonary manifestations of the disorder. To our knowledge, atraumatic loss of a kidney in a patient with alpha1AT deficiency has not previously been reported.

Dental manifestations of osteogenesis imperfecta and abnormalities of collagen I metabolism

The in vitro protein-chemical features and the molecular background of osteogenesis imperfecta (OI), a heritable disorder of collagen I metabolism, have been elucidated in recent years. The aim of our study was to find the prevalence of dentinogenesis imperfecta (DI) and other dental anomalies in 88 patients with OI, to compare clinical with radiologic abnormalities, and to correlate these clinical/radiologic findings with the results of gel electrophoresis and molecular studies of collagen I. Twenty-eight percent of OI patients had DI. Most patients with DI had radiologic abnormalities, but some patients had radiologic signs compatible with DI, but no clinical signs of DI. OI type I patients with DI were more severely affected by OI than those without DI. In OI type III and IV, in contrast, there was no difference in overall severity between patients with and without DI. DI was not associated with any particular molecular aberration in any OI type. If defining DI from the presence of both clinical and radiologic signs, collagen I produced by cultured fibroblasts was qualitatively abnormal from all OI patients with DI. Some OI patients had dental abnormalities not resembling DI. A qualitative collagen abnormality could not be found in any of these patients. Denticles, i.e., calcifications within the pulpal cavity, were found more frequently in OI patients than in control subjects.

Osteogenesis imperfecta: clinical, cephalometric, and biochemical investigations of OI types I, III, and IV

The aim of the study was to analyze craniofacial development in 54 patients with osteogenesis imperfecta (OI), who were classified into OI types I, III, and IV according to clinical criteria, and to relate the findings to the abnormalities in collagen I production. In 33 patients, analysis of radioactively labelled procollagen was performed. Cephalometric radiographs, facial photographs, and CT-scans (a single case) were analyzed and mean facial diagrams for lateral and frontal films were produced based on registration of 221 reference points. Radiographs of 102 male and 51 female Danish students served as control material. In OI type I, size of the skull and jaws was generally slightly reduced, but morphology was within normal limits. In OI type IV and especially type III more severe abnormalities were found; the cranial base was flattened, the maxilla posteriorly inclined, and nearly all size-measurements were reduced. In OI type III the sagittal jaw relations were reduced and a mandibular overjet recorded. Three OI type I patients, whose fibroblasts produced structurally abnormal collagen I, had the stature and several features in the craniofacial region, which corresponded to those recorded for the OI type IV group. Also, in three OI type IV patients whose fibroblasts produced a reduced amount of normal collagen I, craniofacial morphology showed several features resembling type I patients. We conclude that structural abnormalities of collagen I generally give rise to more severe alterations of the craniofacial features than a quantitative defect of collagen I. OI type I patients are only slightly affected in their craniofacial region, while patients with OI type IV and especially type III are moderately to severely affected. The combined cephalometric and biochemical findings suggest that future classification of patients with osteogenesis imperfecta should be based on biochemical/molecular and radiological analyses in combination with clinical criteria rather than on clinical features alone.

Parental mosaicism and autosomal dominant mutations causing structural abnormalities of collagen I are frequent in families with osteogenesis imperfecta type III/IV

Protein-chemical and molecular studies were conducted on all osteogenesis imperfecta (OI) type III/IV patients referred to our hospital during the last 15 y. Of a total of 16 OI type III/IV patients studied, 15 patients were heterozygous for a mutation in one of the two genes coding for collagen I, COL1A1 or COL1A2. Cultured fibroblasts from these 15 patients produced both normal and abnormal collagen I molecules, pointing to a dominant-negative effect of the mutation. Nine mutations had not been described previously. Parental mosaicism was demonstrated in three families. In the 16th child the causative mutation was not found. In conclusion, OI type III/IV in most patients of Western European ancestry is caused by dominant mutations in the genes for collagen I, and recurrence of OI is caused in most cases by parental gonadal mosaicism.

Variable clinical expression in a family with OI type IV due to deletion of three base pairs in COL1A1

We have studied a family with autosomal dominant osteogenesis imperfecta (OI) type IV. Electrophoresis of collagen produced by cultured fibroblasts revealed a slower migrating population of collagen I. Cyanogen bromide peptide mapping localised the structural defect to the area of the alpha 1(1)CB3 peptide. Subsequent sequencing revealed a deletion of nucleotides 1964-1966 in exon 27 of COL1A1. By means of restriction enzyme analysis, the deletion could be detected in all affected family members. This in-frame deletion resulted in the removal of alanine-438 and Glu437Asp substitution in the pro alpha 1(I) collagen chain. Clinical variation was considerable among affected family members. The most consistent clinical features were reduced height and extraosseous manifestations of OI.

Genetic counselling and prenatal diagnosis of osteogenesis imperfecta caused by paternal mosaicism

In a family with recurrent osteogenesis imperfecta (OI) caused by paternal mosaicism, prenatal diagnosis was made using restriction enzyme analysis for a mutation in COL1A2. Parental mosaicism is important to consider in genetic counselling for OI. Prenatal diagnosis of OI is available currently by means of collagen or gene analyses in the first trimester or by ultrasonography in the second trimester.

Osteogenesis imperfecta and malignant hyperthermia. Is there a relationship?

We describe a patient with osteogenesis imperfecta who developed tachycardia, metabolic and respiratory acidosis (pH 7.14, PCO2 8.4 kPa, BE -8.5 mmol.l-1) and hyperthermia up to 40 degrees C during anaesthesia with barbiturates, fentanyl, pancuronium, and nitrous oxide. Malignant hyperthermia was suspected and the patient treated accordingly. Two years later the in-vitro contracture test for malignant hyperthermia was completely normal. We conclude that hypermetabolism in patients with osteogenesis imperfecta is due to unknown mechanisms other than malignant hyperthermia.

Deletion of a Gly-Pro-Pro repeat in the pro alpha2(I) chain of procollagen I in a family with dominant osteogenesis imperfecta type IV

We have investigated one member of a family with dominant osteogenesis imperfecta type IV through three generations. In protein-chemical studies of cultured fibroblasts derived from the proband, collagen I was overmodified, with normal processing of procollagen I, normal thermal stability, and a cyanogen bromide peptide map that suggested a C-terminal location of the structural abnormality in the collagen triple helix. Sequencing of the gene encoding the alpha2(I) chain of collagen I (COL1A2) indicated a nine base-pair deletion of nucleotides 3418-3426. When a polymerase chain reaction product containing the nucleotides in question was electrophoresed in a 12% polyacrylamide gel, two bands with a difference in size of nine base pairs could be shown. Sequencing of the molecular weight band confirmed the deletion of the nine base pairs involving codons 1003-1006 of COL1A2. The deletion introduced a SfiI restriction site that was used for confirmation of the deletion in genomic DNA from the proband. The deletion resulted in the removal of three amino acids (Gly-Pro-Pro), but this did not disrupt the Gly-X-Y sequence of the collagen triple helix, as is often the case in the more common glycine substitutions. We discuss the ways in which this deletion could result in osteogenesis imperfecta.

Gly802Asp substitution in the pro alpha 2(I) collagen chain in a family with recurrent osteogenesis imperfecta due to paternal mosaicism

A proband with osteogenesis imperfecta (OI) type III/IV was born to clinically normal parents, who subsequently had two pregnancies terminated because of OI in the fetuses. Cultured fibroblasts from the proband, one fetus and the father produced abnormal collagen I. Cyanogen bromide mapping localised the defect to the region of the alpha 1(I)CB7 peptide. Sequencing revealed a G to A transition at nucleotide 2814 in COL1A2 in the proband, the fetus, and the father, which resulted in a Gly802Asp substitution in the pro alpha 2(I) collagen chain. About 25% of the paternal alleles from fibroblasts and leucocytes and 40% of paternal alleles from spermatocytes carried the mutation consistent with somatic and germinal mosaicism. For genetic counselling, parental mosaicism must be considered in all sporadic cases of OI.

Phospholipid molecular species with eicosapentaenoic acid (20:5(n-3)) are less stable than species with arachidonic acid (20:4(n-6)) in isolated rat liver cells

We have studied the incorporation of [1-14C]20:5(n-3) and [1-14C]20:4(n-6) in the molecular species of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in isolated rat liver cells. These two fatty acids are present in very different amounts in endogenous phospholipids, with 20:4 as one of the major fatty acids and 20:5 as a minor and very diet-dependent constituent. The main phospholipid species formed from 20:4(n-6) were 16:0-20:4 and 18:0-20:4. When formed, they were stable during incubations of liver cells for 2-3 h. The main species formed from 20:5(n-3) were 16:0-20:5 and 18:0-20:5. After formation, 16:0-20:5 and to a lesser degree 18:0-20:5 were, however, degraded during 1-2 h of incubation, especially in PC. Only small amounts of 22:5(n-3) and very little 22:6(n-3) were formed from 20:5(n-3) and small amounts of 22:4(n-6) were produced from 20:4(n-6). With 20:4(n-6) and 20:5(n-3) as substrates, 20:4-20:4 and 20:5-20:5 molecular species respectively were initially formed in PC and PE but both species were rapidly degraded.

Assignment of congenital cataract Volkmann type (CCV) to chromosome 1p36

Congenital cataract, type Volkmann (McKusick no 115665, gene symbol CCV) is an autosomal dominant eye disease. The disease is characterized by a progressive, central and zonular cataract, with opacities both in the embryonic, fetal and juvenile nucleus and around the anterior and posterior Y-suture. We examined blood samples from 91 members of a Danish pedigree comprising 426 members, by using highly informative short tandem repeat polymorphisms and found the closest linkage of the disease gene (CCV) to a (CA)n dinucleotide repeat polymorphism at locus D1S243 (Zmax = 14.04 at theta M = 0.025 theta F = 0.000), at a penetrance of 0.90. Using two additional chromosome 1 markers, we were able to map the CCV gene in the sequence 1pter-(CCV, D1S243)-D1S468-D1S214. The (enolase 1) gene has been mapped to this area; however, a mutation described in this gene did not give eye disease.

[Neurofibromatosis type 1 in children]

We describe the clinical findings in 75 children with neurofibromatosis type 1 (NF-1, von Recklinghausen disease) diagnosed by the National Institute of Health criteria. The children were on average three years old at the time of their diagnosis. In 12 children complications of NF-1 were noted before diagnosis of their underlying condition, and half of the children had a serious complication, including intracranial tumour, optic glioma, scoliosis, pseudarthrosis tibiae, or mental handicap. Most complications of NF-1 occur before the age of ten. Therefore, and because of its severity and multifaceted presentation, children with NF-1 might benefit from follow-up in a multidisciplinary, specialized clinic.