A de novo loss-of-function DYNC1H1 mutation in a patient with parkinsonian features and a favourable response to levodopa.

Graphical summary of 'A de novo loss-of-function DYNC1H1 mutation in a patient with parkinsonian features and a favourable response to levodopa' by Szczaluba et al..

Novel c.191C>G (p.Pro64Arg) MPV17 mutation identified in two pairs of unrelated Polish siblings with mitochondrial hepatoencephalopathy.

This study reports clinical, biochemical and histopathological findings associated with a novel homozygous MPV17 mutation in four patients with mitochondrial depletion syndrome. The severe course of the disease, which started in the first weeks of life, was dominated by a failure to thrive, hypotonia and liver dysfunction, with relatively mild neurological involvement. All affected infants died by 1 year of age. Laboratory findings included progressive liver failure (hypertransaminasaemia, icterus, and coagulopathy), recurrent hypoglycaemia, lactic acidaemia, hyperferritinaemia, and increased transferrin saturation. Histological and ultrastructural analyses uncovered significant lipid accumulation in hepatocytes and myocytes. A severe decrease in the mitochondrial/nuclear DNA (mtDNA/nDNA) ratio was found post-mortem in the livers (and in one muscle specimen) of both examined patients. Oxidative phosphorylation system (OXPHOS) Western blotting revealed low levels of complexes I, III and IV subunits. The highlights of our findings are as follows: (i) The novel p.Pro64Arg mutation is the second recurrent MPV17 mutation reported. The phenotype associated with the p.Pro64Arg mutation differs from the phenotype of the relatively common p.Arg50Gln mutation, suggesting the existence of a genotype-phenotype correlation. (ii) Tissues collected from patients during autopsy may be useful for both mtDNA/nDNA ratio assessment and OXPHOS Western blotting.

Molecular characterization of Polish patients with familial hypercholesterolemia: novel and recurrent LDLR mutations.

Autosomal dominant hypercholesterolemia (ADH) is caused by mutations in the genes coding for the low-density lipoprotein receptor (LDLR), apolipoprotein B-100 (APOB), or proprotein convertase subtilisin/kexin type 9 (PCSK9). In this study, a molecular analysis of LDLR and APOB was performed in a group of 378 unrelated ADH patients, to explore the mutation spectrum that causes hypercholesterolemia in Poland. All patients were clinically diagnosed with ADH according to a uniform protocol and internationally accepted WHO criteria. Mutational analysis included all exons, exon-intron boundaries and the promoter sequence of the LDLR, and a fragment of exon 26 of APOB. Additionally, the MLPA technique was applied to detect rearrangements within LDLR. In total, 100 sequence variations were identified in 234 (62%) patients. Within LDLR, 40 novel and 59 previously described sequence variations were detected. Of the 99 LDLR sequence variations, 71 may be pathogenic mutations. The most frequent LDLR alteration was a point mutation p.G592E detected in 38 (10%) patients, followed by duplication of exons 4-8 found in 16 individuals (4.2%). Twenty-five cases (6.6%) demonstrated the p.R3527Q mutation of APOB. Our findings imply that major rearrangements of the LDLR gene as well as 2 point mutations (p.G592E in LDLR and p.R3527Q in APOB) are frequent causes of ADH in Poland. However, the heterogeneity of LDLR mutations detected in the studied group confirms the requirement for complex molecular studies of Polish ADH patients.

SURF1 missense mutations promote a mild Leigh phenotype.

UNLABELLED: SURF1 gene mutations are the most common cause of Leigh syndrome (LS), a rare progressive neurodegenerative disorder of infancy, characterized by symmetric necrotizing lesions and hypervascularity in the brainstem and basal ganglia, leading to death before the age of 4 years. Most of the reported mutations create premature termination codons, whereas missense mutations are rare. The aim of the study was to characterize the natural history of LS patients carrying at least one missense mutation in the SURF1 gene. Nineteen such patients (8 own cases and 11 reported in the literature) were compared with a reference group of 20 own c.845_846delCT homozygous patients, and with other LS(SURF-) cases described in the literature. Disease onset in the studied group was delayed. Acute failure to thrive and hyperventilation episodes were rare, respiratory failure did not appear before the age of 4 years. Dystonia, motor regression and eye movement dissociation developed slowly. The number of patients who survived 7 years of life totaled 9 out of 15 (60%) in the 'missense group' and 1 out of 26 (4%) patients with mutations leading to truncated proteins. IN CONCLUSION: (i) The presence of a missense mutation in the SURF1 gene may correlate with a milder course and longer survival of Leigh patients, (ii) normal magnetic resonance imaging (MRI) findings, normal blood lactate value, and only mild decrease of cytochrome c oxidase (COX) activity are not sufficient reasons to forego SURF1 mutation analysis in differential diagnosis.

Sepiapterin reductase deficiency in a 2-year-old girl with incomplete response to treatment during short-term follow-up.

Sepiapterin reductase (SR) catalyses the last step in the tetrahydrobiopterin biosynthesis pathway; it converts 6-pyruvoyl-tetrahydropterin (6-PTP) to BH(4) in an NADPH-dependent reaction. SR deficiency is a very rare autosomal recessive disorder with normal phenylalanine (Phe) concentration in blood and diagnostic abnormalities are detected in CSF. We present a 16-month-old girl with SR deficiency. From the newborn period she presented with an adaptation regulatory disorder. At the age of 3 months, abnormal eye movements with dystonic signs and at 4.5 months psychomotor retardation were noticed. Since that time axial hypotonia with limb spasticity (or rather delayed reflex development), gastro-oesophageal reflux and fatigue at the end of the day has been observed. Brain MRI was normal; EEG was without epileptiform discharges. Analysis of biogenic amine metabolites in CSF at the age of 16 months showed very low HVA and 5-HIAA concentrations. Analysis of CSF pterins revealed strongly elevated dihydrobiopterin (BH(2)), slightly elevated neopterin and elevated sepiapterin levels. Plasma and CSF amino acids concentrations were normal. A phenylalanine loading test showed increased Phe after 1 h, 2 h and 4 h and very high Phe/Tyr ratios. SR deficiency was confirmed in fibroblasts and a novel homozygous g.1330C>G (p.N127K) SPR mutation was identified. On L-dopa and then additionally 5-hydroxytryptophan, the girl showed slow but remarkable progress in motor and intellectual ability. Now, at the age of 3 years, she is able to sit; expressive speech is delayed (to 1 1/2 years), passive speech is well developed. Her visual-motor skills, eye-hand coordination and social development correspond to the age of 2 1/2 years.

Hypoxanthine-guanine phosphoribosylotransferase deficiency--the spectrum of Polish mutations.

Hypoxanthine-guanine phosphoribosyltransferase (HPRT; EC 2.4.2.8) deficiency (OMIM 308000) is an inborn error of purine metabolism. The defect causes three overlapping clinical syndromes: Lesch-Nyhan disease (LND; OMIM 300322), HPRT-related hyperuricaemia with neurologic dysfunction (HRND) and hyperuricaemia alone (HRH; OMIM 300322). During the period 1977-2007, 18 patients belonging to 12 Polish families and one Latvian family with HPRT deficiency have been identified. The majority of patients had a typical LND phenotype, three patients were classified as HRH and one patient as an intermediate phenotype (HRND). Genetic analysis revealed 12 different HPRT1 mutations, five of them being unique. In two typical Lesch-Nyhan families a novel single-base substitution, c.220T>G (p.Phe74Val), and a deletion of seven nucleotides, c.395_401del7 (p.Ile132LysfsX3), were found. Another novel single-base substitution, c.295T>G (p.Phe99Val), was identified in a patient with severe partial deficiency of HPRT with neurological dysfunction. In patients belonging to the HRH group, two transitions were detected: c.481G>A (p.Ala161Thr) and c.526C>T (p.Pro176Ser). Other mutations identified in Polish patients, c.131A>G (p.Asp44Gly), c.222C>A (p.Phe74Leu), c.385-1G>A (p.Asn129_Glu134del), c.482C>A (p.Ala161Glu), c.508C>T (p.Arg170Ter) and c.569G>A (p.Gly190Glu), have been reported previously in unrelated patients and are located within one of the clusters of hot spots of the HPRT1 gene (exons 3, 7 and 8). Patients with partial phenotypes presented mutations predicted to permit some degree of residual enzyme function (single-base substitutions). All mutations, except c.508C>T (p.Arg170Ter), were found in single families only, indicating the lack of any common mutation causing HPRT deficiency in Poland.

High frequency of missense mutations in glycogen storage disease type VI.

Deficiency of liver glycogen phosphorylase in glycogen storage disease (GSD) type VI results in a reduced ability to mobilize glucose from glycogen. Six mutations of the PYGL gene, which encodes the liver isoform of the enzyme, have been identified in the literature. We have characterized eight patients from seven families with GSD type VI and identified 11 novel PYGL gene defects. The majority of the mutations were missense, resulting in the substitution of highly conserved residues. These could be grouped into those that were predicted to affect substrate binding (p.V456M, p.E673K, p.S675L, p.S675T), pyridoxal phosphate binding (p.R491C, p.K681T), or activation of glycogen phosphorylase (p.Q13P) or that had an unknown effect (p.N632I and p.D634H). Two mutations were predicted to result in null alleles, p.R399X and [c.1964_1969inv6;c.1969+1_+4delGTAC]. Only 7 of the 23 (30%) reported PYGL alleles carry nonsense, splice site or frameshift mutations compared to 68-80% of affected alleles of the highly homologous muscle glycogen phosphorylase gene, PYGM, that underlie McArdle disease. There was heterogeneity in the clinical symptoms observed in affected individuals. These varied from hepatomegaly and subclinical hypoglycaemia, to severe hepatomegaly with recurrent severe hypoglycaemia and postprandial lactic acidosis. We conclude that deficiency of liver glycogen phosphorylase is predominantly the result of missense mutations affecting enzyme activity. There are no common mutations and the severity of clinical symptoms varies significantly.

Transferrin hypoglycosylation in hereditary fructose intolerance: using the clues and avoiding the pitfalls.

Hereditary fructose intolerance (HFI) is caused by a deficiency of aldolase B due to mutations of the ALDOB gene. The disease poses diagnostic problems because of unspecific clinical manifestations. We report three cases of HFI all of whom had a chronic disease with neurological, nephrological or gastroenterological symptoms, whereas nutritional fructose intolerance, the pathognomonic sign of HFI, was apparent only in retrospect. In all patients a hypoglycosylated pattern of transferrin isoforms was found but was misinterpreted as a sign of CDG Ix. The correct diagnosis was achieved with marked delay (26, 36 and 24 months, respectively) by sequencing of the ALDOB gene two common mutations were identified on both alleles or on one (A150P/A175D, A150P/-, and A150P/A175D). The diagnosis was further supported by normalization of transferrin isoforms on a fructose-free diet. Data available in two patients showed that following the fructose restriction the type I pattern of carbohydrate-deficient transferrin detectable on fructose-containing diet disappeared after 3-4 weeks. These cases illustrate that in the first years of life HFI may show misleading variability in clinical presentation and that protein glycosylation analysis such as transferrin isofocusing may give important diagnostic clues. However, care should be taken not to misinterpret the abnormal results as CDG Ix as well as to remember that a normal profile does not exclude HFI due to the possibility of spontaneous fructose restriction in the diet. The presented data also emphasize the usefulness of ALDOB mutation screening for diagnosis of HFI.

Difficulties in recognition of pyruvate dehydrogenase complex deficiency on the basis of clinical and biochemical features. The role of next-generation sequencing.

Pyruvate dehydrogenase complex (PDHc) defect is a well-known cause of mitochondrial disorders (MD) with at least six responsible genes (PDHA1, PDHB, DLAT, DLD, PDHX, PDP1). The aim of this work was to assess the diagnostic value of biochemical methods in recognition of PDHc defect in Polish patients with suspicion of MD. In the first step, Western blot of the E1α subunit was performed on 86 archive muscle bioptates with suspicion of MD. In the second step, Sanger PDHA1 sequencing was performed in 21 cases with low E1α expression. In the third step, 7 patients with negative results of PDHA1 sequencing were subjected to whole-exome sequencing (WES). This protocol revealed 4 patients with PDHA1 and one with DLD mutations. Four additional probands were diagnosed outside the protocol (WES or Sanger sequencing). The molecular characterization of PDHc defect was conducted in a total of 9 probands: 5 according to and 4 off the protocol. Additionally, two affected relatives were recognized by a family study. Altogether we identified seven different PDHA1 changes, including two novel variants [c.464T > C (p.Met155Thr) and c.856_859dupACTT (p.Arg288Leufs*10)] and one DLD variant. The lactate response to glucose load in the PDHA1 subset was compared to a subset of non PDHc-related MD. Opposite responses were observed, with an increase of 23% and decrease of 27%, respectively. The results show that determining lactate response to glucose load and muscle E1α expression may contribute to distinguishing PDHc-related and other MD, however, WES is becoming the method of choice for MD diagnostics.

Genomic organization of the human phosphomannose isomerase (MPI) gene and mutation analysis in patients with congenital disorders of glycosylation type Ib (CDG-Ib).

CDG-Ib is the "gastro-intestinal" type of the congenital disorders of glycosylation (CDG) and a potentially treatable disorder. It has been described in patients presenting with congenital hepatic fibrosis and protein losing enteropathy. The symptoms result from hypoglycosylation of serum- and other glycoproteins. CDG-Ib is caused by a deficiency of mannose-6-phosphate isomerase (synonym: phosphomannose isomerase, EC 5.3.1.8), due to mutations in the MPI gene. We determined the genomic structure of the MPI gene in order to simplify mutation detection. The gene is composed of 8 exons and spans only 5 kb. Eight (7 novel) different mutations were found in seven patients with a confirmed phosphomannose isomerase deficiency, analyzed in the context of this study: six missense mutations, a splice mutation and one insertion. In the last, the mutation resulted in an unstable transcript, and was hardly detectable at the mRNA level. This emphasizes the importance of mutation analysis at the genomic DNA level.

Extremely low serum pyridoxal 5'-phosphate in children with familial hypophosphatemic rickets.

The apparent vitamin B-6 status of 31 children with familial hypophosphatemic rickets (FHR) was determined. All children had alkaline phosphatase activity that was high-normal to elevated for their ages. A sensitive assay for pyridoxal 5'-phosphate (PLP) indicated that 15 of the 31 children had an undetectable (less than 0.2 nmol/L) concentration of the vitamer--the lowest values yet reported in human serum. The 16 remaining children had concentrations of the vitamer so low that they indicated a potential severe vitamin B-6 deficiency. However, none of the children had ever presented with any of the classical vitamin B-6-deficiency symptoms. Treatment of three additional FHR children with 100 mg pyridoxine.HCl/d resulted in a moderate and transient elevation of their serum PLP concentrations, a dramatic elevation of their erythrocyte PLP concentrations, and no improvement in clinical condition. Serum or plasma PLP concentrations are an inappropriate index for determining vitamin B-6 status in people with FHR and perhaps in others with elevated alkaline phosphatase activity.

Abolished phosphaturic response to parathormone in adult patients with Fahr disease and its restoration after propranolol administration.

The similar localization of intracranial calcification in hypoparathyroidism and in Fahr disease without parathyroid gland disorder suggests that in these two disorders the pathomechanism of calcium phosphate deposition in the brain may be similar. It may be that in Fahr disease some factors, such as chronic respiratory alkalosis, could lead to hypoparathyroidism-like changes in the brain tissue. Abolition of the phosphaturic response to parathormone (PTH) was recently demonstrated in acute experimental hypocapnia. In three adult patients with Fahr disease, a tendency towards compensatory respiratory alkalosis and arterial hypocapnia was found. The parathormone test revealed a marked decrease in phosphaturia response to PTH, but normal cAMP response. In one patient, the parathormone test was repeated during propranolol administration and showed a considerable improvement in the phosphaturic response to parathormone. It is postulated that chronic hyperventilation and hypocapnia as well as phosphaturic resistance to PTH, intracellular increase of phosphate concentration and development of hypoparathyroidism-like intracranial calcification in patients with Fahr disease could all be caused by disturbance of adrenergic receptors and their relationship to PTH receptors.

SURF1 gene mutations in Polish patients with COX-deficient Leigh syndrome.

One of the most frequent forms of Leigh syndrome (LS), a severe neurodegenerative, genetically heterogenous disease, is associated with cytochrome c oxidase (COX) deficiency. No mutations in any of the 13 polypeptide subunits of human COX have been detected in LS patients. Recently, SURF1, a positional candidate gene for LS has been identified on chromosome 9q34. We present the identification of SURF1 mutations in a randomly chosen group of Polish patients with a classical form of LS. Sequence analysis revealed the presence of a novel 704T-->C transition (Met235Thr), and two recurrent dinucleotide deletions (758delCA, 845delCT), as well as one novel polymorphic 573C-->G transversion (Thr191Thr). 845delCT was identified in 66% of all our patients in homozygous or heterozygous form. Our study confirms the recent observations that SURF1 is consistently involved in disorders of the mitochondrial respiratory chain in patients with typical Leigh syndrome.

X-linked hypophosphatemia in Polish patients. 1. Mutations in the PHEX gene.

We present twenty-nine PHEX gene mutations extending our previous work, giving it to a total of 37 different mutations identified in Polish patients with familial or sporadic X-linked hypophosphatemia. Deletions, insertions and nucleotide substitutions leading to frameshift (27%), stop codon (29%), splice site (24%), and missense mutations (20%) were found. The mutations are distributed along the gene; exons 3, 4, 11, 12, 14, 15, 17, 20 and 22 are regions with the most frequent mutation events. Four mutations, P534L, G579R, R549X and IVS15+1nt, recurred in three, four, two and three unrelated patients, respectively. They have also been detected in affected persons from other countries. Twenty-eight mutations are specific for Polish population and almost all of them are unique. Most of the identified mutations are expected to result in major changes in protein structure and/or function.

X-linked hypophosphatemia in Polish patients. 2. Analysis of clinical features and genotype-phenotype correlation.

Clinical and molecular data of 59 affected persons from 36 unrelated families with XLH (36 probands and 23 members of their families) were analysed. Characteristic phenotypic features (degree of leg deformities, growth failure, tooth abnormalities, tubular reabsorption of phosphate, serum phosphate and 1,25-dihydroxyvitamin D3 concentrations, head length and hearing defect in some cases) were assessed in relation to the type and localisation of 29 different PHEX gene mutations. The severity of clinical symptoms did not strictly depend upon the type and localisation of the PHEX gene mutation. A hearing defect was correlated with mutations in the beginning fragment, while tooth abnormalities and increased head length with the mutations in the beginning and the terminal fragment of the gene. Phosphate and vitamin D3 supplementation usually slowed progressive growth retardation and leg bowing. Our results point to the probability that alternative splicing occurs in the PHEX gene, producing several active forms of the PHEX protein. Some of them might be involved in bone turnover and dentin formation, others in renal phosphate uptake and vitamin D3 metabolism.

13C NMR spectroscopy: a convenient tool for detection of argininosuccinic aciduria.

Proton decoupled high resolution 13C NMR spectra of argininosuccinic acid have been measured in a series of dilute water solutions of various acidity. These data have provided a basis for unequivocal determination of the presence of this metabolite in the investigated sample. The method additionally enables simultaneous rough estimation of the metabolite concentration. In order to check the practicability of the usage of this spectroscopy for diagnostic purposes, the spectra of several unprocessed urine samples have been recorded including three from patients with argininosuccinic aciduria. It has been concluded that 13C NMR spectroscopy can be a convenient method of recognising the above syndrome and probably many other inborn metabolic errors which manifest themselves with the excretion of the marker metabolite in amounts comparable to (or larger than) creatinine.

Asymptomatic decreased activities of hepatic glucose-6-phosphatase and glycogen phosphorylase in a number of children with chronic liver disease.

The evaluation of hepatic degradation of glycogen in patients with different chronic liver diseases was carried out on the basis of: a) specific activities of hepatic enzymes involved in catabolism of glycogen; b) level of glycogen in liver biopsies; c) concentration of glucose and cAMP in serum after the intravenous administration of glucagon. In 13 out of 35 patients investigated the activity of glucose-6-phosphatase was decreased to 14-50% of the control value. In the livers of 3 patients glycogen phosphorylase activity was decreased to 10% of the control value. In patients with the significantly low activities of hepatic glucose-6-phosphatase and phosphorylase a, however, normal catabolism of glycogen in the liver was observed, neither hypoglycemia nor abnormal glycogen storage in liver biopsies nor abnormal response to glucagon being found. In the group of patients with decreased and normal activities of glucose-6-phosphatase and phosphorylase a, biochemical parameters in the serum (i.e. markers of liver damage) were not detectable. Possible causes of the selective and asymptomatic decrease in the activities of glucose-6-phosphatase and phosphorylase a are discussed.

[Idiopathic juvenile osteoporosis with the symptoms suggesting nervous system damage]. / Mlodziencza osteoporoza idiopatyczna z objawami sugerujacymi uszkodzenie ukladu nerwowego.

10 children with final diagnosis of idiopathic juvenile osteoporosis were admitted to the Department of Neurology because of suspected lesion of nervous system. The main clinical features were gait disturbances and pain. Radiological examination was decisive for diagnosis. The authors discuss the course of disease and effect of the treatment.

[Suspected pyruvate carboxylase deficiency in 4 children with Leigh disease]. / Podejrzenie deficytu karboksylazy pirogronianu u 4 dzieci z choroba Leigha.

Clinical observations and results of investigations of pyruvic acid metabolism are reported in 4 children in whom subacute necrotizing encephalomyelopathy of Leigh was diagnosed intravitally. Attention is called to the similarity of the clinical manifestations with its onset in the first year of life, deficient body weight and growth, progressing neurological disturbances (weakening of muscle power, tremor, ataxia, nystagmus), course with periods of exacerbations, tachypnoea, skin changes (hirsutism, telangiectasia, perspiration), death at the age of 2-3 years. The biochemical changes in all children included raised serum levels of lactic acid, pyruvic acid and alanine, and acid-base equilibrium disturbances with metabolic acidosis (relatively balanced respiratory alkalosis). The results of the test of intravenous loading with glucose and alanine carried out in all children indicated indirectly reduced activity of pyruvate carboxylase. In one child histological examination of the brain carried out postmortem confirmed the diagnosis of Leigh's disease.

[Role of the parathyroid glands in the pathogenesis of intracerebral calcifications]. / Udzial przytarczyc w patogenezie zwapnien sródmózgowych.

Investigations of calcium-phosphate metabolism were carried out in a group of 11 children and adults with intracerebral calcifications. It was possible to isolate three different pathogenetic types of calcifications in the striatum and dentate nuclei in the cerebellum. The authors suggest restriction of the term "Fahr's syndrome" to cases without true of false hypoparathyroidism. The assessment of the calcium-phosphate metabolism, and particularly, the test with parathyroid hormone, seem to be an indispensable element in the differential diagnosis of this type of intracerebral calcifications.