Molecular testing of 163 patients with Morquio A (Mucopolysaccharidosis IVA) identifies 39 novel GALNS mutations.

Morquio A (Mucopolysaccharidosis IVA; MPS IVA) is an autosomal recessive lysosomal storage disorder caused by partial or total deficiency of the enzyme galactosamine-6-sulfate sulfatase (GALNS; also known as N-acetylgalactosamine-6-sulfate sulfatase) encoded by the GALNS gene. Patients who inherit two mutated GALNS gene alleles have a decreased ability to degrade the glycosaminoglycans (GAGs) keratan sulfate and chondroitin 6-sulfate, thereby causing GAG accumulation within lysosomes and consequently pleiotropic disease. GALNS mutations occur throughout the gene and many mutations are identified only in single patients or families, causing difficulties both in mutation detection and interpretation. In this study, molecular analysis of 163 patients with Morquio A identified 99 unique mutations in the GALNS gene believed to negatively impact GALNS protein function, of which 39 are previously unpublished, together with 26 single-nucleotide polymorphisms. Recommendations for the molecular testing of patients, clear reporting of sequence findings, and interpretation of sequencing data are provided.

Molecular analysis of 30 Niemann-Pick type C patients from Spain.

Mutations in the NPC1 or NPC2 gene are responsible for Niemann-Pick type C (NPC) disease (OMIM #257220), an autosomal recessive neurodegenerative lysosomal storage disorder caused by an incorrect regulation of intracellular lipid trafficking. A molecular analysis carried out in 30 unrelated patients identified 43 distinct mutations in the NPC1 gene, 12 of which had not been previously described. The novel NPC1 alleles were four amino acid substitutions (p.F995L, p.F1079S, p.L1106P and p.G1209E), a nonsense mutation (p.E1089X), a 1-bp insertion (p.L1117PfsX4), an in-frame deletion (p.N916del), four intronic changes (c.58-3280C>G, c.882-28A>T, c.2604+5G>A and c.3591+5G>A) that affect the splicing mechanism, and the first deletion including the whole gene described in NPC disease. In all the splice site mutations, the formation of abnormal spliced transcripts was confirmed by cDNA analysis, and mRNA degradation by the nonsense-mediated mRNA decay process was also assessed. As it has been previously reported in this disease, genotype-phenotype correlations are limited due to the large number of private mutations. We describe for the first time one homozygous patient for p.I1061T mutation, who presented the severe infantile clinical onset, and another patient with the variant biochemical phenotype, whose clinical presentation was the neonatal form of the disease.

Molecular analysis of Sanfilippo syndrome type C in Spain: seven novel HGSNAT mutations and characterization of the mutant alleles.

The Sanfilippo syndrome type C [mucopolysaccharidosis IIIC (MPS IIIC)] is caused by mutations in the HGSNAT gene, encoding an enzyme involved in heparan sulphate degradation. We report the first molecular study on several Spanish Sanfilippo syndrome type C patients. Seven Spanish patients, one Argentinean and three Moroccan patients were analysed. All mutant alleles were identified and comprised nine distinct mutant alleles, seven of which were novel, including four missense mutations (p.A54V, p.L113P, p.G424V and p.L445P) and three splicing mutations due to two point mutations (c.633+1G>A and c.1378-1G>A) and an intronic deletion (c.821-31_821-13del). Furthermore, we found a new single nucleotide polymorphism (SNP) (c.564-98T>C). The two most frequent changes were the previously described c.372-2A>G and c.234+1G>A mutations. All five splicing mutations were experimentally confirmed by studies at the RNA level, and a minigene experiment was carried out in one case for which no fibroblasts were available. Expression assays allowed us to show the pathogenic effect of the four novel missense mutations and to confirm that the already known c.710C>A (p.P237Q) is a non-pathogenic SNP. Haplotype analyses suggested that the two mutations (c.234+1G>A and c.372-2A>G) that were present in more than one patient have a common origin, including one (c.234+1G>A) that was found in Spanish and Moroccan patients.

Clinical experience with miglustat therapy in pediatric patients with Niemann-Pick disease type C: a case series.

Niemann-Pick disease type C (NP-C) is an inherited neurovisceral lysosomal lipid storage disease characterized by progressive neurological deterioration. Different clinical forms have been defined based on patient age at onset: perinatal, early-infantile (EI), late-infantile (Li), juvenile and adult. We evaluated the efficacy and tolerability of miglustat in 16 symptomatic NP-C patients, with comparative reference to one neurologically asymptomatic, untreated patient. All patients were categorized according to age at neurological disease onset, and were assessed using a standardized clinical assessment protocol: disability and cognitive function scales, positron emission tomography (PET), and biochemical markers. PET and disability scale evaluations indicated that cerebral hypometabolism and neurological symptoms were stabilized during treatment in juvenile-onset NP-C patients. EI and Li NP-C patients, who had higher disease severity at baseline (treatment start), showed increased disability scores and progressive cerebral hypometabolism during follow up. Similarly, while cognitive scale scores remained relatively stable in patients with juvenile NP-C, cognition deteriorated in EI and Li patients. Plasma chitotriosidase (ChT) activity was lower in the juvenile NP-C subgroup than in EI and Li patients, and generally increased in patients who discontinued treatment. Plasma CCL18/PARC and ChT activities indicated greater macrophagic activity in EI and Li patients versus juveniles. Miglustat was generally well tolerated; frequent adverse events included diarrhea and flatulence, which were managed effectively by dietary modification and loperamide. Overall, miglustat appeared to stabilize neurological status in juvenile-onset NP-C patients, but therapeutic benefits appeared smaller among younger patients who were at a more advanced stage of disease at baseline.

Molecular analysis of mucopolysaccharidosis type IIIB in Portugal: evidence of a single origin for a common mutation (R234C) in the Iberian Peninsula.

Mucopolysaccharidosis type IIIB (Sanfilippo B disease) is a rare autosomal recessive disorder caused by defective alpha-N-acetylglucosaminidase (NAGLU). We examined the NAGLU gene in 11 MPS IIIB Portuguese patients, having identified five novel (M1K, W147X, G304V, S522P, and R533X) and four previously reported mutations (W168X, R234C, R565W and R643C). R234C attained the high prevalence of 32% of the mutated alleles. Because R234C had already been reported to be common in Spanish patients, a haplotypic analysis was conducted to address the question of its origin in the Iberian Peninsula. Three neutral markers were studied that allowed for the identification of the probable founder haplotype (174-234-G) on which R234C arose. The sharing of the ancestral haplotype by Portuguese and Spanish patients clearly implied a common origin of the mutation in Iberia, through an event that was inferred to have been rather recent. Therefore, the reconstructed history of R234C explains the high incidence of the mutation in Iberian patients with Sanfilippo B disease.

Niemann-Pick C disease in Spain: clinical spectrum and development of a disability scale.

OBJECTIVES: To describe the clinical evolution of Niemann-Pick C disease to identify possible factors involved in the diagnosis and severity of the disease. METHODS: A clinical database and a severity scale was created to evaluate 45 patients diagnosed with Niemann-Pick type C in the last 28 years in Spain. RESULTS: Complete clinical data were obtained from 30 patients, all were confirmed to have mutations in the NPC1 gene. Regarding clinical form, 3 were perinatal, 7 severe infantile, 6 late infantile, 11 juvenile and 3 adult. Biochemical phenotype was classic in 26. Splenomegaly was present in 28 patients (93%) with a wide range of age at detection. The first symptom of neurological disease was clumsiness, followed in 2-4 years by cerebellar signs. Ophthalmoplegia appeared 2-4 years later and became complete 1-2 years after onset. Dysarthria appeared by the time of complete ophthalmoplegia. Diagnosis was made before the onset of neurological signs in patients with the severe infantile form, at the time of onset of cerebellar signs in the late infantile form and complete ophthalmoplegia in late onset forms. CONCLUSIONS: In our series, splenomegaly is present in 96% of patients, even in late onset forms during the first years of life. Clumsiness in children with otherwise normal motor development precedes the onset of ataxia by 2-4 years in Niemann Pick type C. A disability scale could be useful for monitoring evolution, establishing possible phenotypic correlations and evaluating future therapies.

Clinical Evolution After Enzyme Replacement Therapy in Twins with the Severe Form of Maroteaux-Lamy Syndrome.

Mucopolysaccharidosis type VI (MPS VI) is a progressive, autosomal, recessive lysosomal disorder. This disorder, due to a deficiency in N-acetylgalactosamine-4-sulfatase (ASB), results in an accumulation of glycosaminoglycan (GAG), causing multiple organ failures. In this study, monochorionic biamniotic twins with the severe form of MPS VI underwent enzyme replacement therapy (ERT) with weekly infusions of recombinant human ASB (galsulfase) at 1 mg/kg. After 9 years of ERT, a comprehensive clinical examination was performed. Several types of biochemical, immunological, and genetic investigations were also conducted. Both twins showed the typical symptoms and signs of MPS VI at baseline, including short stature, progressive dysmorphic facial features, and dysostosis multiplex. Twin 2 presented stronger multisystemic involvement, with marked musculoskeletal, neurological, and odontological components. She also developed an ischemic spinal cord lesion after surgery, which is the first case described in the literature in Maroteaux-Lamy syndrome. However, the extent of disease was found to be equally stabilized in the two sisters, concretely the cardiac and respiratory functions and body length. The early diagnosis and treatment of MPS VI are critical for an optimal clinical outcome, and further evidence for the new treatment strategies is needed.

Reduced levels of sialic acid in the plasma membrane during hepatocellular proliferation.

When rats were infused with a solution containing triiodothyronine, amino acids, glucagon and heparin (solution A) the hepatocytes increased DNA synthesis and decreased plasma membrane sialic acid. In order to study whether the reduced levels of sialic acid in the plasma membrane were associated with hepatocyte proliferation, different mixtures of three components of solution A were infused into rats and the DNA synthetic activity as well as the sialic acid content measured. Results reported here show a correlation between DNA synthetic activity and sialic acid reduction suggesting that the decrease in the plasma membrane sialic acid can be a pre-replicative step associated to cell proliferation.

[Outcome of two patients with Hurler's syndrome under enzyme replacement therapy with human recombinant alpha-L-iduronidase]. / Evolución de dos pacientes con síndrome de Hurler en tratamiento con enzima recombinante humana alpha-L-iduronidasa.

We performed a prospective study of two patients with Hurler's syndrome (aged 4.8 years and 17 months at the beginning of the intervention) under enzyme replacement therapy with human recombinant alpha-L-iduronidase for 452 and 28 weeks respectively. The aim of this study was to analyze the safety and efficacy of the intervention during the treatment periods. Several diagnostic imaging tests, clinical examinations, and serial laboratory determinations were performed to demonstrate the effectiveness of the therapy in both patients. In patient 1 (a boy aged 4.8 years, homozygote W402X), the treatment was always intended to be palliative because of the advanced stage of the disease. In patient 2 (a 17-month-old girl, heterozygote W402X) the treatment was initiated early with subsequent clinical stabilization without acquisition of regressive factors. Bone marrow transplantation from an unrelated donor was successful. Currently, because of the lack of histocompatible bone marrow donors, transplantation of hematopoietic stem cells from umbilical cord blood or peripheral blood are being performed with satisfactory results. In the future, gene therapy may be able to prevent the diseases associated with Hurler's syndrome and halt the neurocognitive deterioration characteristic of these patients.

Evidence of a single origin for the most frequent mutation (R402W) causing glutaryl-CoA dehydrogenase deficiency: identification of 3 novel polymorphisms and haplotype definition.

Glutaryl-CoA dehydrogenase (GCDH) deficiency causes glutaric aciduria type I (GA I), an inborn error of metabolism that is characterized clinically by dystonia and dyskinesia, biochemically by excretion of glutaric and 3-hydroxyglutaric acids in urine, and pathologically by neural degeneration of the caudate and putamen. To date, over 70 mutations in GCDH gene have been identified, single prevalent mutations have been found in communities in which GA I is particularly common, but generally GA I is heterogeneous. The most frequent mutation in Caucasians, R402W, has been identified in 12-16% of alleles. Here we report the frequency of mutation R402W in GA I Spanish patients, the characterization of three novel GCDH polymorphisms (IVS2+48T>C, IVS2-82T>G and 3'UTR 1518A>G) which, in combination with the two polymorphisms previously described (IVS2+64G>C, 1209G>T) gave rise to the first definition of GCDH haplotypes and their frequencies in control population. Linkage disequilibrium has been found between mutation R402W and a specific haplotype, suggesting a single origin for this mutation. Hum Mutat 15:207, 2000.

Calmodulin may decrease cell surface sialic acid and be involved in the expression of fibronectin during liver regeneration.

The decrease of sialic acid in plasma membrane glycoproteins and the expression of cell surface fibronectin were studied during the pre-replicative phase of liver regeneration. The aim of this study was to correlate these cell-surface events to the intracellular surge of calmodulin observed a few hours after partial hepatectomy. The fact that calmodulin decreased the specific activity of UDP-N-acetyl-D-glucosamine 2'-epimerase, a key regulatory enzyme in the biosynthesis of glycoprotein sialic acids, and that trifluoperazine prevented the desialylation indicates that the membrane desialylation is a calmodulin-dependent process. On the other hand, Western blotting using anti-rat fibronectin antibody in trifluoperazine-treated animals suggests that calmodulin may also be involved in the surface expression of fibronectin in regenerating hepatocytes.

X-linked adrenoleukodystrophy: phenotype distribution and expression of ALDP in Spanish kindreds.

X-linked adrenoleukodystrophy (X-ALD) is a neurodegenerative disorder caused by an impairment in peroxisomal beta-oxidation of very long straight-chain fatty acids (VLCFAs). Six clinical phenotypes have been delineated: childhood cerebral (CCALD), adolescent cerebral (AdolCALD), adult cerebral (ACALD), adrenomyeloneuropathy (AMN), Addison-only (AO), and presymptomatic (PALD). The distribution of phenotypes varies in different countries. We have diagnosed biochemically 60 X-ALD Spanish patients belonging to 48 kindreds. Their phenotypic distribution was: CCALD plus AdolCALD, 33%; ACALD, 16%; AMN, 27%; AO, 12%; and PALD, 12%. These results contrast with the distribution described in other countries, due to a higher prevalence of the ACALD form. Regarding the expression of the protein product (ALDP), we studied 17 kindreds using immunochemical techniques and found absence of ALDP in 84% of cases. We also studied 13 females from 7 negative ALDP kindreds in order to correlate ALDP expression and the carrier status established by VLCFA measurement. In one case with normal VLCFA levels in serum and fibroblasts, we observed mosaicism in ALDP expression. This fact supports the use of this technique for identifying carriers.

Mutation and haplotype analyses in 26 Spanish Sanfilippo syndrome type A patients: possible single origin for 1091delC mutation.

Mucopolysaccharidosis IIIA, also known as Sanfilippo syndrome type A, is an autosomal recessive storage disorder caused by deficiency of sulfamidase. The disease results in severe central nervous system degeneration often with mild somatic features that may delay the clinical diagnosis. Molecular analyses would allow early and unequivocal heterozygote detection, providing a useful tool for genetic counselling. About 40 mutations have been reported in the sulfamidase gene, with a very uneven distribution in different patient populations. We have previously described the high prevalence of mutation 1091delC in a small number of Spanish Sanfilippo A patients. The aim of the present work is to extend the mutational study to a total of 26 unrelated patients and perform haplotype analysis in order to study the origin of some mutations. The whole coding region of the gene was scanned by SSCP analysis and sequencing. This allowed the identification of 14 different mutations, corresponding to 90% of the mutant alleles. Seven of these mutations were only found in this Spanish group of patients, three of which, R150W, R433Q and R433W, are described here for the first time. We have also analyzed four internal polymorphisms and constructed the corresponding haplotypes. Chromosomes bearing mutation 1091delC show a conserved haplotype suggesting a common origin for this mutation. Moreover, all other mutations found twice or more also have conserved haplotypes for those polymorphic markers.

Angiokeratoma corporis diffusum associated with beta-mannosidase deficiency.

BACKGROUND: Angiokeratoma corporis diffusum (ACD) was at one time thought to be synonymous with Anderson-Fabry disease. However, it is well known that widespread angiokeratomas may also be found in other lysosomal enzyme disorders, as well as in patients with normal enzyme activities. beta-Mannosidase deficiency was first described in humans in 1986; since then, only 11 cases of beta-mannosidase deficiency, which occurred in 8 families, have been reported. Although the clinical manifestations are varied, mental retardation and neurologic disorders are present in practically all patients. OBSERVATIONS: We describe a 22-year-old woman who, since the age of 12 years, presented with progressive ACD affecting the lower limbs and the buttocks. Enzymatic studies revealed beta-mannosidase deficiency in cultured fibroblasts and in samples of serum and leukocytes. The patients's parents in turn exhibited intermediate enzyme levels, thus confirming the recessive autosomal hereditary nature of the disease. With the exception of an introverted character, the patient demonstrated no other anomalies. CONCLUSIONS: This is the first case of beta-mannosidase deficiency diagnosed as a result of purely dermatologic findings, in the form of ACD. beta-Mannosidase deficiency should therefore be included when screening for enzyme abnormalities in patients with ACD, even in the absence of neurologic disorders or mental retardation.

[The contribution of molecular genetics to hereditary neurometabolic disorders]. / Aportación de la genética molecular a los trastornos neurometabólicos hereditarios.

In this article we review the main contribution of molecular genetics to understanding hereditary neurometabolic disorders. This includes improvement in diagnosis, especially in X chromosome linked disorders and illness due to the protein or gene expression in tissues which are difficult to obtain. Moreover molecular biology, as a diagnostic tool, has contributed decisively to genetic counselling by permitting firm diagnosis of carriers and prenatal diagnosis. Other important contributions, although more minor, are determination of the prognosis and establishment of individualized treatment based on the genotype. We also review the relation between the disease and the susceptibility allele, the possibility of making genetic population studies and of establishing presymptomatic diagnoses. It is concluded that understanding the molecular basis of a particular disorder has opened the way to diagnosis and prognosis. It also opens the door to genetic therapy, the study of other factors which may affect the action of genes and especially the proteinome.

[Late infantile and juvenile form of GM2-gangliosidosis variant B1]. / Fenotipo infantil tardío y juvenil de la variante B1 de gangliosidosis GM2.

INTRODUCTION: Variant B1 is a rare form of GM2-gangliosidosis characterized by the presence of a mutation in the hexosaminidase A gene (HEXA) leading to a defect in the catalytic region of the alpha-subunit of beta-hexosaminidase A (alpha beta heterodymer). The mutated Hex A has almost normal activity against the natural synthetic substrates (4-methylumbelliferyl-N-acetyl-beta-D-glucosamine, 4MU-NAG) but is unable to hydrolyse GM2-ganglioside and the sulphated synthetic substrates (4MU-NAGS). The first and more frequent mutation described in the alpha-subunit gene associated to B1 variant GM2-gangliosidosis was a G533-->A transition (DN allele) resulting in Arg178His substitution. CLINICAL CASES: Here, we report the clinical, enzymatic and molecular characterization in two variant B1 late infantile and juvenile cases. Both cases presented regression of mental skills leading to dementia, epilepsy and severe motor impairment with dystonic involuntary movements and quadriplegia. In the late infantile case (death at 5 years and 8 months), cherry-red spot was also present. Enzymatic assays were performed in fibroblasts, leukocytes and serum and confirmed the abnormally low beta-hexosaminidase A activity against sulphated substrate despite a normal or nearly normal total hexosaminidase activity (unsulphated substrates). The patient with the late infantile phenotype was found to be compound heterozygote for the DN allele whilst the juvenile form was homozygote for that mutation. CONCLUSION: Variant B1 form of GM2-gangliosidosis is a rare and heterogeneous condition that must be kept in mind when evaluating neurodegenerative disorders associated with speech or gait disturbances, dystonia, seizures and pyramidal features.

[Niemann-Pick type C disease: From neonatal cholestasis to neurological degeneration. Different phenotypes]. / Enfermedad de Niemann-Pick tipo C: desde una colestasis neonatal hacia un deterioro neurológico. Variabilidad fenotípica.

INTRODUCTION: Niemann-Pick type C is a lysosomal storage disorder caused by a defect in intracellular trafficking of cholesterol. It is a rare disease, usually caused by mutations in NPC1 gene, but in some cases by mutations in NPC2 gene. Usually it is present in the paediatric age with a great variability of clinical manifestations. This disease leads to neurological degeneration with various age-related symptoms. Transient neonatal cholestasis, the appearance of splenomegaly and/or hepatomegaly may occur years before the neurological symptoms. PATIENTS AND METHODS: We report 6 cases diagnosed in our unit in the last 20 years. We reviewed the clinical manifestations, neuroradiological findings (MRI) and molecular analysis of all of them. RESULTS: The disease began before 6 years of age and 5 cases had liver dysfunction and cholestasis in the neonatal period. Ascites was detected in 2 cases in prenatal period. Five cases have or had splenomegaly. Mutations in NPC1 gene were detected in all of them. CONCLUSIONS: It is important to understand this disease and the identification of early clinical symptoms to make an early diagnosis, leading to appropriate treatment and avoiding unnecessary tests. Moreover, it is important to suitably advise families and provide them with genetic counselling.

[Our experience in the diagnosis of peroxisomal diseases with an abnormal fatty acid profile]. / Nuestra experiencia diagnóstica en enfermedades peroxisomales con alteración del perfil de ácidos grasos

INTRODUCTION: The aetiology and clinical features of peroxisomal diseases vary widely. An altered very-long-chain fatty acid (VLCFA) profile is commonly found in many of these diseases, and this makes it easier to point the diagnosis in the right direction. PATIENTS AND METHODS: We review our experience in the diagnosis of cases of peroxisomal diseases with an altered VLCFA pattern; these were determined in serum only when there was a strong clinical suspicion up to the end of 1998, when their quantification by chromatography was introduced into our laboratory. RESULTS: The neuropaediatric database included 10,239 cases between May 1990 and 1st October 2007. Ten cases of peroxisomal disease with an altered VLCFA pattern were identified, all of them males. There were two cases of Zellweger syndrome spectrum, one unclassified peroxisomal oxidation defect and seven X-linked adrenoleukodystrophies (four with neurological compromise and three with no neurological damage; two were identified in siblings of patients and the other due to the presence of Addison's syndrome). CONCLUSIONS: In our 10 cases, the diagnosis was guided by the clinical or familial features that led to the determination of VLCFA. Being able to determine VLCFA makes early systematic diagnosis of patients possible. At present, VLCFA determination is performed when there is a clinical suspicion of Zellweger spectrum, suspected X-linked adrenoleukodystrophy/adrenomyeloneuropathy of unclear causation, Addison's disease, both in males and females, and above all in cases of chronic encephalopathy of unknown causation, with or without prenatal onset.