GM2 gangliosidosis in British Jacob sheep.

GM2 gangliosidosis (Tay-Sachs disease) was diagnosed in 6- to 8-month-old pedigree Jacob lambs from two unrelated flocks presenting clinically with progressive neurological dysfunction of 10 day's to 8 week's duration. Clinical signs included hindlimb ataxia and weakness, recumbency and proprioceptive defects. Histopathological examination of the nervous system identified extensive neuronal cytoplasmic accumulation of material that stained with periodic acid--Schiff and Luxol fast blue. Electron microscopy identified membranous cytoplasmic bodies within the nervous system. Serum biochemistry detected a marked decrease in hexosaminidase A activity in the one lamb tested, when compared with the concentration in age matched controls and genetic analysis identified a mutation in the sheep hexa allele G444R consistent with Tay-Sachs disease in Jacob sheep in North America. The identification of Tay-Sachs disease in British Jacob sheep supports previous evidence that the mutation in North American Jacob sheep originated from imported UK stock.

Pathology of GM2 gangliosidosis in Jacob sheep.

The G(M2) gangliosidoses are a group of lysosomal storage diseases caused by defects in the genes coding for the enzyme hexosaminidase or the G(M2) activator protein. Four Jacob sheep from the same farm were examined over a 3-year period for a progressive neurologic disease. Two lambs were 6-month-old intact males and 2 were 8-month-old females. Clinical findings included ataxia in all 4 limbs, proprioceptive deficits, and cortical blindness. At necropsy, the nervous system appeared grossly normal. Histologically, most neurons within the brain, spinal cord, and peripheral ganglia were enlarged, and the cytoplasm was distended by foamy to granular material that stained positively with Luxol fast blue and Sudan black B stains. Other neuropathologic findings included widespread astrocytosis, microgliosis, and scattered spheroids. Electron microscopy revealed membranous cytoplasmic bodies within the cytoplasm of neurons. Biochemical and molecular genetic studies confirmed the diagnosis of G(M2) gangliosidosis. This form of G(M2) gangliosidosis in Jacob sheep is very similar to human Tay-Sachs disease and is potentially a useful animal model.

Vitamin B12-responsive severe leukoencephalopathy and autonomic dysfunction in a patient with "normal" serum B12 levels.

Leukoencephalopathy and autonomic dysfunction have been described in individuals with very low serum B(12) levels (<200 pg/ml), in addition to psychiatric changes, neuropathy, dementia and subacute combined degeneration. Elevated homocysteine and methylmalonic acid levels are considered more sensitive and specific for evaluating truly functional B(12) deficiency. A previously healthy 62-year-old woman developed depression and cognitive deficits with autonomic dysfunction that progressed over the course of 5 years. The patient had progressive, severe leukoencephalopathy on multiple MRI scans over 5 years. Serum B(12) levels ranged from 267 to 447 pg/ml. Homocysteine and methylmalonic acid levels were normal. Testing for antibody to intrinsic factor was positive, consistent with pernicious anaemia. After treatment with intramuscular B(12) injections (1000 µg daily for 1 week, weekly for 6 weeks, then monthly), she made a remarkable clinical recovery but remained amnesic for major events of the last 5 years. Repeat MRI showed partial resolution of white matter changes. Serum B(12), homocysteine and methylmalonic acid levels are unreliable predictors of B(12)-responsive neurologic disorders, and should be thoroughly investigated and presumptively treated in patients with unexplained leukoencephalopathy because even long-standing deficits may be reversible.

Spontaneous appearance of Tay-Sachs disease in an animal model.

Tay-Sachs disease (TSD) is a progressive neurodegenerative disorder due to an autosomal recessively inherited deficiency of beta-hexosaminidase A (Hex A). Deficiency of Hex A in TSD is caused by a defect of the alpha-subunit resulting from mutations of the HEXA gene. To date, there is no effective treatment for TSD. Animal models of genetic diseases, similar to those known to exist in humans, are valuable and essential research tools for the study of potentially effective therapies. However, there is no ideal animal model of TSD available for use in therapeutic trials. In the present study, we report an animal model (American flamingo; Phoenicopterus ruber) of TSD with Hex A deficiency occurring spontaneously in nature, with accumulation of G(M2)-ganglioside, deficiency of Hex A enzymatic activity, and a homozygous P469L mutation in exon 12 of the hexa gene. In addition, we have isolated the full-length cDNA sequence of the flamingo, which consists of 1581 nucleotides encoding a protein of 527 amino acids. Its coding sequence indicates approximately 71% identity at the nucleotide level and about 72.5% identity at the amino acid level with the encoding region of the human HEXA gene. This animal model, with many of the same features as TSD in humans, could represent a valuable resource for investigating therapy of TSD.

Very long chain acyl-CoA dehydrogenase deficiency in a pair of mildly affected monozygotic twin sister in their late fifties.

Very long-chain acyl-CoA dehydrogenase (VLCAD) catalyses the initial step of mitochondrial beta-oxidation of long-chain fatty acids with a chain length of 14 to 20 carbons. Deficiency of VLCAD activity has been associated with a range of phenotypes, including a severe lethal form presenting in the infantile period and a milder variant with onset in childhood. Varying rates of residual enzyme activity partly explain the heterogeneity in presentations. Here we report the course of disease in a pair of monozygotic twin sisters who were diagnosed in their late forties during an evaluation for rhabdomyolysis and fatigue. Interestingly, the patients' complaints were most severe during puberty and declined significantly after the menopause. The basis for this observation is uncertain, but may be related to hormonally-mediated changes in lipid metabolism that may occur at these times. As metabolic decompensation can be associated with significant morbidity, timely diagnosis of VLCAD deficiency is important. The introduction of appropriate dietary measures (i.e. avoidance of fasting, long-chain fat restriction and supplementation with medium-chain triglycerides) greatly reduces the likelihood of complications.

Rapid detection of three large novel deletions of the aspartoacylase gene in non-Jewish patients with Canavan disease.

Canavan disease (CD), an autosomal recessive neurodegenerative disorder, is caused by mutations in the aspartoacylase (ASPA) gene. In the present study, the ASPA gene was analyzed in 24 non-Jewish patients with CD from 23 unrelated families. Within this cohort, we found three large novel deletions of approximate 92, 56, and 12.13 kb in length, using both self-ligation of restriction endonuclease-digested DNA fragments with long-distance inverse PCR and multiplex dosage quantitative PCR analysis of genomic DNA. The 92 kb large deletion results in complete absence of the ASPA gene in one homozygous and one compound heterozygous patient, respectively. The 56 kb large deletion causes absence of the majority of the ASPA gene except for exon 1 alone in a compound heterozygous patient. The 12.13 kb deletion involves deletion of the ASPA gene from intron 3 to intron 5 including exons 4 and 5 (I3 to E4E5I5) in a compound heterozygous patient. Patients with the three large deletions clinically manifested severe symptoms at birth, including seizures. Our study showed that the combined use of long-distance inverse PCR and multiplex dosage quantitative PCR analysis of genomic DNA is a helpful and rapid technique to search for large deletions, particularly for detection of large deletions in compound heterozygous patients.

Globoid cell leukodystrophy (Krabbe disease): normal umbilical cord blood galactocerebrosidase activity and polymorphic mutations.

Globoid cell leukodystrophy is an inherited metabolic disorder of the central nervous system caused by deficiency of the lysosomal enzyme galactocerebrosidase. Haematopoietic stem cell transplantation is the only available effective treatment. The engraftment from normal donors provides competent cells able to correct the metabolic defect. Umbilical cord blood cells have proved to significantly decrease complications and improve engraftment rate compared to adult marrow cells in haematopoietic stem cell transplantation. Umbilical cord blood cells must be of sufficient activity to provide central nervous system recovery after engraftment is obtained. Galactocerebrosidase activity is known to be affected by two polymorphic alleles found at nucleotides 502 and 1637 of the cDNA for this gene. This enzyme activity and the polymorphic alleles noted above were analysed in 83 random samples of umbilical cord blood. The activity, assayed with the fluorogenic substrate 6-hexadecanoylamino-4-methylumbelliferyl-beta-galactopyranoside, in those with neither polymorphic allele was 4.6 +/- 1.7 units (nmol/h per mg protein). This optimal choice of cord blood was found in only 24% of specimens. Homozygotes for 1637T > C with activity of only 1.5 +/- 0.4 units represented 16% of the samples. Those heterozygous for 1637T > C with slightly better activity (2.3 +/- 0.7 units) represented 52% of the samples. Choice of umbilical cord blood for haematopoietic stem cell transplantation, therefore, requires consideration not only of cell quantity and HLA compatibility but also selection for normal alleles to obtain maximal enzymatic activity for central nervous system correction.

Neuropsychological assessment of patients with late onset GM2 gangliosidosis.

OBJECTIVE: To characterize cognitive status in a sample of individuals with late-onset GM2 gangliosidosis (commonly referred to as late-onset Tay-Sachs disease). METHODS: Seventeen subjects (13 men, 4 women) diagnosed with GM2 gangliosidosis were evaluated. Subjects ranged in age from 18 to 56 years and were in various stages of disease progression. Subjects underwent comprehensive neuropsychological assessment. Impairment was defined as performance more than 1.6 SD below the normative mean. RESULTS: Group mean performance was within the denoted normal range on all measures except on a task assessing visual sequencing and set shifting. Approximately one-half of the sample scored in the impaired range on measures of processing speed, visual sequencing, and set shifting. One-third of the sample also scored in the impaired range on measures of delayed verbal recall. Impairment tended to be restricted to a subset of the sample, as 5 of the 14 subjects able to undergo formal testing accounted for 70% of the total number of impaired scores. If the three subjects unable to participate in formal testing are also considered impaired, 47% of the current sample exhibited significant cognitive impairment in at least one cognitive domain. CONCLUSION: In late-onset GM2 gangliosidosis, there is a risk of impairment in executive functioning and memory as well as cerebellar dysfunction. Dementia was not present in any subjects in the current sample.

A neurological symptom survey of patients with type I Gaucher disease.

Gaucher disease is an inborn error of glycosphingolipid metabolism resulting from deficiency of the lysosomal enzyme glucocerebrosidase. The majority of the patients (with type I disease) do not have primary central nervous system involvement. However, several studies have noted that secondary neurological complications may develop as a consequence of nerve root or spinal cord compression following vertebral body collapse or, for those with coagulation disorders, bleeding within confined compartments. An epidemiological survey was conducted to ascertain the incidence of neurological symptoms in patients with Gaucher disease type I (GD I). The survey included a review of the patients' medical history, an estimate of Gaucher disease severity according to a modified Symptom Severity Index (SSI), and completion of a questionnaire regarding their neurological status and Quality of Life (QoL) according to the SF-36 Health Survey. Seventy-three per cent of respondents were found to have experienced at least one neurological complaint in the preceding 3 months. Adult patients with Gaucher disease often have other medical problems unrelated to their primary diagnosis. Thus, the high incidence of neurological complaints in these patients may be attributable to concurrent medical problems and/or side-effects from concomitant medications. These issues may influence patients' assessment of their disease severity and/or response to treatment.

Therapeutic effects of astrocytes expressing both tyrosine hydroxylase and brain-derived neurotrophic factor on a rat model of Parkinson's disease.

Tyrosine hydroxylase (TH) and brain-derived neurotrophic factor (BDNF), expressed in normal astrocytes, were used in combination for the treatment of Parkinson's disease (PD) symptoms in a rat model. Normal neonatal rat astrocytes were co-transfected with a vector expressing BDNF (AAVBDNF) and a retroviral vector expressing TH (termed TH-BDNF-DA(+) cells), and then implanted into the striatum of PD rats induced by 6-hydroxydopamine. TH-BDNF-DA(+) cells compensated for a severe insufficiency of endogenous dopaminergic neurons in the PD rats, resulting in a significant improvement of PD symptoms. The decrease in the rotational rate of PD rats implanted with TH-BDNF-DA(+) cells was more marked than that in PD rats implanted with normal astrocytes expressing either TH or BDNF alone (termed TH(+) and BDNF(+) cells, P<0.01 and 0.001, respectively), and suggested a synergistic effect between TH and BDNF. In contrast, the rotational rate was not altered from the baseline in PD rats without treatment or implanted with parental rat astrocytes alone (P>0.05). BDNF protected the dopaminergic neurons from apoptosis induced by 6-hydroxydopamine, and significantly increased the long-term survival of TH-positive cells in the striatum. Our data indicate that the combined use of TH and BDNF has a synergistic therapeutic effect, and is more efficient for the treatment of PD than a single gene therapy using either TH or BDNF alone.

Identification and characterization of novel mutations of the aspartoacylase gene in non-Jewish patients with Canavan disease.

Canavan disease, an inherited leukodystrophy, is caused by mutations in the aspartoacylase (ASPA) gene. It is most common among children of Ashkenazi Jewish descent but has been diagnosed in many diverse ethnic groups. Two mutations comprise the majority of mutant alleles in Jewish patients, while mutations in the ASPA gene among non-Jewish patients are different and more diverse. In the present study, the ASPA gene was analysed in 22 unrelated non-Jewish patients with Canavan disease, and 24 different mutations were found. Of these, 14 are novel, including five missense mutations (E24G, D68A, D249V, C152W, H244R), two nonsense mutations (Q184X, E214X), three deletions (923delT, 33del13, 244delA), one insertion mutation (698insC), two sequence variations in one allele ([10T>G; 11insG]), an elimination of the stop codon (941A>G, TAG-->TGG, X314W), and one splice acceptor site mutation (IVS1 - 2A>T). The E24G mutation resulted in substitution of an invariable amino acid residue (Glu) in the first esterase catalytic domain consensus sequence. The IVS1 - 2A>T mutation caused the retention of 40 nucleotides of intron 1 upstream of exon 2. The results of transient expression of the mutant ASPA cDNA containing these mutations in COS-7 cells and assays for ASPA activity of patient fibroblasts indicated that these mutations were responsible for the enzyme deficiency. In addition, patients with the novel D249V mutation manifested clinically at birth and died early. Also, patients with certain other novel mutations, including C152W, E214X, X314W, and frame shift mutations in both alleles, developed clinical manifestations at an earlier age than in classical Canavan disease.

Rapid detection of the two common mutations in Ashkenazi Jewish patients with mucolipidosis type IV.

Among Ashkenazi Jewish individuals with mucolipidosis IV (ML IV), two mutations in the ML IV gene, IVS3-1A --> G and delEX1-EX7, account for more than 95% of disease alleles. The reported method of genotyping for the delEX1-EX7 mutation involves a cumbersome multistep procedure. In the present study, a new simplified one-step procedure is described that detects this mutation in both patients and carriers. An improved procedure is also described for detection of the IVS3-1A --> G mutation. Using these improved procedures, we have characterized the ML IV mutant alleles in 27 patients and 95 of their relatives from 22 families, and in 123 unrelated and unaffected Ashkenazi Jewish controls. Of the 27 ML IV patients, 16 patients (59.3%) were found to be homozygous for the IVS3-1A --> G mutation and 1 patient (3.7%) homozygous for the delEX1-EX7 mutation. Additionally, 9 patients (33.3%) were compound heterozygotes for IVS3-1A --> G/delEX1-EX7. Among the 123 Ashkenazi Jewish controls, two individuals were identified as heteroallelic with one IVS3-1A --> G mutation (carrier frequency: approximately 1 in 61); none showed the delEX1-EX7 mutation. The modifications described here provide a more facile means of genotyping patients and carriers and expand the possibilities for screening at-risk populations.

Mutations in noncoding regions of the proteolipid protein gene in Pelizaeus-Merzbacher disease.

BACKGROUND: Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive dysmyelinating disorder of the CNS. Duplications or point mutations in exons of the proteolipid protein (PLP) gene are found in most patients. OBJECTIVE: To describe five patients with PMD who have mutations in noncoding regions of the PLP gene. METHODS: Quantitative multiplex PCR and Southern blot analyses were used to detect duplication of the PLP gene, and DNA sequence analysis, including exon-intron borders, was used to detect mutation of the PLP gene. RESULTS: Duplication of the PLP gene was ruled out, and mutations were identified in noncoding regions of five patients in four families with PMD. In two brothers with a severe form of PMD, a G to T transversion at IVS6+3 was detected. This mutation resulted in skipping of exon 6 in the PLP mRNA of cultured fibroblasts. A patient who developed nystagmus at 16 months and progressive spastic ataxia at 18 months was found to have a 19-base pair (bp) deletion of a G-rich region near the 5' end of intron 3 of the PLP gene. A patient with a T to C transition at IVS3+2 and a patient with an A to G transition at IVS3+4 have the classic form of PMD. These, like the 19-bp deletion, are in intron 3, which is involved in PLP/DM20 alternative splice site selection. CONCLUSIONS: Mutations in introns of the PLP gene, even at positions that are not 100% conserved at splice sites, are an important cause of PMD.

Isolation and characterization of the normal canine beta-galactosidase gene and its mutation in a dog model of GM1-gangliosidosis.

The acid beta-galactosidase cDNA of Portuguese Water dogs was isolated and sequenced. The entire coding region of the gene consists of 2004 nucleotides encoding a protein of 668 amino acids. Its encoding sequence indicates approximately 86.5% identity at the nucleotide level and about 81% identity at the amino acid level with the encoding region of the human acid beta-galactosidase gene. The deduced amino acid sequence contains a 24-amino-acid putative signal sequence, six possible glycosylation sites, and seven cysteine residues. A homozygous recessive mutation, causing canine GM1-gangliosidosis, was identified at nucleotide G200-->A in exon 2 resulting in an Arg60-->His (mutation R60H) amino acid substitution. The mutation creates a new restriction enzyme site for Pml1. Genotyping 115 dog samples for this acid beta-galactosidase gene alteration readily distinguished affected homozygous recessives (n=5), heterozygous carriers (n=50) and normal homozygotes (n=60). DNA mutation analysis provided a method more specific than enzyme assay of beta-galactosidase for determination of carriers.

The Gaucher registry: demographics and disease characteristics of 1698 patients with Gaucher disease.

BACKGROUND: The Gaucher Registry, the largest database of patients with Gaucher disease (GD) worldwide, was initiated to better delineate the progressive nature of the disorder and determine optimal therapy. This report describes the demographic and clinical characteristics of 1698 patients with GD before they received enzyme replacement therapy. METHODS: Physicians worldwide who treat patients with GD were invited to submit prospective and retrospective data for an ongoing registry, using standardized data collection forms, for central processing and review. RESULTS: Most patients were from the United States (45%) and Israel (17%), but patients are from 38 countries. Most (94%) had type 1 GD, fewer than 1% had type 2, and 5% had type 3. Mutant allele frequency data, available for 45% of patients, showed the most common alleles to be N370S (53%), L444P (18%), 84GG (7%), and IVS2+1 (2%). Twenty-five percent of L444P homozygotes (13 of 52 patients) had type 1 GD phenotype. Mean age at diagnosis in patients with the N370S/N370S genotype was 27.2 years (SD, 19.7 years); in L444P/L444P patients, 2. 3 years (SD, 3.2 years). Histories of bone pain and radiological bone disease were reported by 63% and 94% of patients, respectively; both were more likely in asplenic patients than in patients with spleens. Mean spleen and liver volumes were 19.8 and 2.0 multiples of normal, respectively. Anemia and thrombocytopenia were present in 64% and 56%, respectively. Thrombocytopenia was present in 13% of asplenic patients. CONCLUSIONS: The Gaucher Registry permits a comprehensive understanding of the clinical spectrum of GD because of the uniquely large sample size. The Registry will be useful in evaluating the effects of specific therapies in GD and the possible influences of environment, ethnicity, and genotype on the natural history of the disorder.

Measurements from normal umbilical cord blood of four lysosomal enzymatic activities: alpha-L-iduronidase (Hurler), galactocerebrosidase (globoid cell leukodystrophy), arylsulfatase A (metachromatic leukodystrophy), arylsulfatase B (Maroteaux-Lamy).

Umbilical cord blood (UCB) has received increasing attention as a source of unrelated hematopoietic stem cells for transplantation. Lysosomal diseases have been effectively treated and normal enzymatic activity has occurred subsequent to engraftment using UCB. The use of donor cells with normal amounts of enzyme, rather than those from carriers whose level may be 50% or less, is an obvious goal. The frequency of such heterozygotes varies from 1:10 to 1:140 or lower depending upon the disease at issue. We assayed the levels of lysosomal enzymes in normal UCB in random samples as well as those used for transplantation. We measured the following enzymatic activities: alpha-l-iduronidase (Hurler), galactocerebrosidase (globoid cell leuko- dystrophy) and arylsulfatase A (metachromatic leukodystrophy). For the latter, levels of activity in UCB are comparable to those found in adult blood. In the case of arylsulfatase B (Maroteaux-Lamy) a level lower than adult level was found. An informed choice by the transplanting physician based on the activity of the relevant enzyme in the UCB donor will provide a better opportunity for an improved prognosis for more complete correction of the recipient's primary disease. Bone Marrow Transplantation (2000) 25, 541-544.

Lower limb cold exposure induces pain and prolonged small fiber dysfunction in Fabry patients.

In Fabry disease, an X-linked alpha-galactosidase A deficiency, painful crises and limb paresthesias are possibly linked to thermal exposure. Small nerve fiber function has not yet been tested after cold challenge. In two Fabry patients (15 and 17 years old), their heterozygote mother, their healthy sister, and eight controls, we determined warm and cold perception thresholds at the dorsal foot and the lower medial calf (method of limits, Somedic-Thermotest), before and 1, 5, 10 and 15 min after 30 s immersion of one leg into 5 degrees C water. Discomfort was rated from 0 to 10. At baseline, thermal thresholds of all participants were normal. In contrast to controls, the patients tolerated 30 s cold stimulation only with interruptions. The mother aborted stimulation after 6 s because of pain. The patients and their mother reported intense burning pain and numbness during and after stimulation. After cold exposure, thermal sensation was highly abnormal for 20 min in one and 80 min in the other brother. In controls, thermal thresholds were somewhat elevated after stimulation but normalized within 10.0+/-4.6 min. Discomfort during cold exposure was rated 8-10 by the patients and their mother, but 3-5 by the healthy persons. We assume that glycolipid accumulation in cutaneous and vasa nervorum vessels as well as small nerve axons accounts for skin and small fiber malperfusion during cold induced vasoconstriction. Transitory ischemia initiated burning pain and prolonged small fiber dysfunction.

Niemann-Pick disease.

Niemann-Pick disease, originally defined in terms of its histology as a reticuloendotheliosis, is now subdivided on the basis of biochemical and molecular criteria into two separate classes. This categorization has been aided by the discovery of the genes for acid sphingomyelinase, deficient in types A and B, and for the NPC-1 protein, deficient in types C and D, and the finding of mutations in each. Animal models of type A and type C disease are known or have been developed. These models have been utilized in therapeutic trials of bone marrow transplantation and gene transfection of stem cells and in studies of disease pathogenesis. Lysosphingomyelin has been implicated in the nervous system involvement associated with type A disease in humans and accumulations of the NPC-1 protein and apolipoprotein D have been found in murine NP-C brain. Cells from both human and murine Niemann-Pick disease type A have been studied to assess the role of acid sphingomyelinase in signal transduction pathways involving cell proliferation, differentiation, and apoptosis.

Sympathetic skin response following thermal, electrical, acoustic, and inspiratory gasp stimulation in familial dysautonomia patients and healthy persons.

To determine whether sympathetic skin response (SSR) testing evaluates afferent small or efferent sympathetic nerve fiber dysfunction, we studied SSR in patients with familial dysautonomia (FD) in whom both afferent small and efferent sympathetic fibers are largely reduced. We analyzed whether the response pattern to a combination of stimuli specific for large or small fiber activation allows differentiation between afferent and efferent small fiber dysfunction. In 52 volunteers and 13 FD patients, SSR was studied at palms and soles after warm, cold and heat as well as electrical, acoustic, and inspiratory gasp stimulation. In addition, thermal thresholds were assessed at four body sites using a Thermotest device (Somedic; Stockholm, Sweden). In volunteers, any stimulus induced reproducible SSRs. Only cold failed to evoke SSR in two volunteers. In all FD patients, electrical SSR was present, but amplitudes were reduced. Five patients had no acoustic SSR, four had no inspiratory SSR. Thermal SSR was absent in 10 patients with abnormal thermal perception and present in one patient with preserved thermal sensation. In two patients, thermal SSR was present only when skin areas with preserved temperature perception were stimulated. In patients with FD, preserved electrical SSR demonstrated the overall integrity of the SSR reflex but amplitude reduction suggested impaired sudomotor activation. SSR responses were dependent on the perception of the stimulus. In the presence of preserved electrical SSR, absent thermal SSR reflects afferent small fiber dysfunction. A combination of SSR stimulus types allows differentiation between afferent small or efferent sympathetic nerve fiber dysfunction.