Late-onset Krabbe Disease Research Articles

Myoclonic Seizures in Krabbe Disease: A Unique Presentation in Late-Onset Type

Krabbe disease is a rare, recessively inherited degenerative disorder of myelin, caused by a deficiency of the lysosomal enzyme galactocerebroside beta-galactosidase. Ninety-five percent of cases begin in early infancy, typically presenting with irritability, hypertonicity, tonic spasms, visual loss with optic atrophy, and occasionally seizures. In 5% of cases, symptoms begin late, between 15 months and 10 years, usually presenting with spastic paralyses, cerebellar ataxia, visual failure, and peripheral neuropathy. Seizures occasionally develop months to years after symptom onset. In a review of 50 such cases from the world literature, in only two did seizures signal the onset. This report describes an 18-month-old male with late-onset Krabbe disease who is the first such reported patient presenting with myoclonic seizures, an epileptic encephalopathy normally thought to reflect gray matter disease.

Late-Onset Krabbe’s Disease Mimicking Acute Disseminated Encephalomyelitis

A previously healthy 3-year-old female presented with rapidly progressive neurologic deterioration. She was initially diagnosed with acute disseminated encephalomyelitis but was subsequently found to have late-onset Krabbe's disease.

Hematopoietic Cell Transplantation Ameliorates Clinical Phenotype and Progression of the CNS Pathology in the Mouse Model of Late Onset Krabbe Disease

Krabbe disease is a genetic demyelinating disease caused by a deficiency of galactosylceramidase. The majority of cases are of infantile onset with rapid clinical course. A rare late onset form with milder clinical symptoms also exists. The latter form has been reported to respond well to the bone marrow transplantation (BMT) therapy. We tested whether the BMT could be an effective therapy for the mouse model of the late onset form, saposin-A-/- (SAP-A-/-) mice. We used green fluorescent protein transgenic mice as the donors. Chimeric SAP-A-/- mice that received BMT showed very little evidence of neurologic symptoms. At postnatal day 190 when severe demyelination was evident in naive SAP-A-/- mice, demyelination was virtually absent in the brain of chimeric SAP-A-/- mice. Presence of residual enzyme activity, at the time of rapid myelination in SAP-A-/- mice, appears to limit initial inflammatory responses and macrophage infiltration, thereby preventing progression of demyelination in the CNS in SAP-A-/- mice. In contrast, the peripheral nerves showed features of hypertrophic neuropathy with hypomyelination and onion bulb formation, suggesting that there are different cellular responses to the BMT in the CNS and PNS.

AAV-Mediated expression of galactocerebrosidase in brain results in attenuated symptoms and extended life span in murine models of globoid cell leukodystrophy

Globoid cell leukodystrophy (GLD) or Krabbe disease is a neurodegenerative disorder caused by a deficiency of galactocerebrosidase (GALC) activity. GALC is required for the lysosomal degradation of galactosylceramide, psychosine, and possibly other galactolipids. This process is extremely important during active myelination. In the absence of functional GALC, psychosine accumulates, resulting in the apoptotic death of myelin-producing cells. While most patients are infants who do not survive beyond 2 years of age, some older patients are also diagnosed. Hematopoietic stem cell transplantation has proven to have a positive effect on the course of some patients with late-onset Krabbe disease. Murine models of this disease provide an excellent opportunity to evaluate therapeutic alternatives including gene therapy. In this study we used serotype 1 AAV to express mouse GALC under the control of the human cytomegalovirus promoter. Direct administration of these viral particles into the brains of neonatal mice with GLD resulted in sustained expression of GALC activity, improved myelination, attenuated symptoms, and prolonged life span. While this treatment also resulted in significant pathological improvements, the treated mice died with symptoms similar to those of the untreated mice. Additional initiatives may be required to prevent the onset of disease and reverse the course of the disease in animal models and human patients.

Late Infantile Onset Krabbe Disease in Siblings with Cortical Degeneration and Absence of Cerebral Globoid Cells

Krabbe disease, a disorder caused by the deficiency of lysosomal galactosylceramidase, is typically associated with cerebral white matter degeneration, cortical sparing, accumulation of macrophages ("globoid cells"), and ultrastructural needle-shaped inclusions. Two sisters presented with progressive neurological deterioration beginning before the age of 2.5 years. The first, who died at the age of 9 years, exhibited profound destruction of cerebral white matter with sparing of subcortical fibers but no globoid cells. The brain of the second, who died at the age of 15 years and who had a proven galactosylceramidase deficiency, exhibited white matter destruction, previously undescribed circumscribed spongiform cortical degeneration (postcentral, inferior temporal, cingulate), and cerebellar atrophy, but no globoid cells. The peripheral nerve biopsies from both girls exhibited typical needle-shaped inclusions in Schwann cells. These observations confirm the rare reports that Krabbe disease is not always associated with globoid cells in the brain. Psychosine, which accumulates in the brain, might be toxic to cortical neurons following prolonged survival. The reason for the regional susceptibility in the cerebral cortex is unknown.

Brain-stem auditory and visual evoked potentials in children with Krabbe disease

Objective There are few reports in the literature detailing brain-stem auditory and visual evoked potentials (BAEP and VEP) in children with Krabbe disease (KD). The purpose of this study was to provide a descriptive analysis of the BAEP and VEP findings in these children. Methods Charts of children with KD were reviewed. BAEP and VEP studies performed on these children were reviewed; findings in the early infantile and late onset KD (EIKD, LOKD, respectively) groups were also examined. Likelihood ratios (LR) for the neurophysiologic tests being abnormal in the various groups were also determined. Results BAEP abnormalities were seen in 15/17 (88%) children with EIKD and 2/5 (40%) children with LOKD, LR statistically significant. In the EIKD group, all 13 symptomatic children had an abnormal BAEP, whereas 2/4 (50%) of the pre-symptomatic children had similar findings, LR statistically significant. VEP abnormalities were noted in 8/15 (53%) children with EIKD and none of the children with LOKD, LR statistically significant. In the EIKD group, the 8/12 (67%) symptomatic children had an abnormal VEP, whereas none of the pre-symptomatic children did, LR statistically significant. Subgroup analyses of the LOKD subgroups did not yield significant findings. Conclusions BAEP abnormalities are among the first objective indications of central nervous system disease in children with EIKD. VEP abnormalities occur later in the course of the illness. Both tests are less helpful in children with LOKD. Significance BAEP and VEP testing is helpful in objective evaluation of children with KD.

Peripheral neuropathy with hypomyelinating features in adult-onset Krabbe's disease

We describe three brothers suffering from Krabbe's disease with onset in the fifth decade. The proband showed a complete deficiency of leukocyte enzyme galactocerebrosidase and was found to be heterozygous for two previously described mutations: G>A809 and 502T/del consisting of a 30 kb deletion. In all three brothers the neurological examination showed features of asymmetrical peripheral neuropathy associated with pyramidal signs and the electrophysiological examination showed a generalized slowing of nerve conduction velocities. Two patients died at 59 and 61 years of age due to respiratory failure. Both the proband and his brother underwent a sural nerve biopsy. In the former the most striking finding was the presence of uniformly thin myelin sheaths without evidence of demyelination; a complete absence of fibers was found in the latter. Our findings confirm that peripheral neuropathy may be the presenting feature of late-onset Krabbe's disease. Hypomyelination rather than demyelination may represent the distinguishing pathological finding of this condition.

Residual galactosylsphingosine (psychosine) β-galactosidase activities and associated GALC mutations in late and very late onset Krabbe disease

Background: Krabbe disease (globoid-cell leukodystrophy; GLD) is caused by mutations in the GALC gene. β-galactocerebrosidase (GALC) is a specific β-galactosidase which is defective in GLD. About 90% of GLD patients have an infantile course by fatal cerebral demyelination, but 10% have a later onset (LOGLD) of symptoms and survive for one or several decades. Methods: Activities of GALC towards galactosylceramide (GC) and galactosylsphingosine (psychosine; PS) were determined in white blood cells and cultured fibroblasts derived from GLD patients and controls using tritium-labelled natural substrates. In the galactosylsphingosine (psychosine) β-galactosidase (GALC-PS) assay, a thin layer chromatographic technique was used to separate enzymatically released radioactive galactose. Results: Both galactosylceramide β-galactosidase (GALC-GC) and GALC-PS activities were reduced by at least 85% of the normal in all but 2 of the 10 GLD patients studied. In particular, one 23-year-old severely demyelinated LOGLD patient was strongly deficient (11% of the normal) in GALC-GC but apparently normal for GALC-PS activity. This patient's GALC genotype was the 30-kb-deleted/502T allele combined with a wild-type allele in the 1637C background known to slightly reduce GALC-GC activity. Further, of six LOGLD patients, both of 62- and 63-year-old brothers had the deleted allele combined with an 809G>A mutated 1637C allele. The sibs had strongly reduced GALC-GC and GALC-PS activities but became clinically remarkable only in their 50s with a severe mental downhill course in one of them. Conclusions: A GALC genotype with one deleted and one polymorphic GALC activity-reducing allele can lead to enzymatic and clinical signs of LOGLD in the absence of marked GALC-PS deficiency. If an active PS hydrolysis in the fibroblasts of a LOGLD patient also reflected such hydrolysis in the brain, the psychosine hypothesis for GLD may need to be revised.

Evaluation of myelination by means of the T 2 value on magnetic resonance imaging

The progress of myelination in the cerebrum was evaluated by visual inspection, and magnetic resonance (MR) imaging and the transverse relaxation time (T 2) was calculated from double echo images. Twenty-three pediatric cases, who did not show intracranial organic changes on MR examination, were included. The T 2 values in the corpus callosum (CC), frontal deep white matter (FWM), occipital deep white matter (OWM) and centrum semiovale (CS) were calculated, and the changes in these values with age were followed. During the first year of life, a rapid decrease in the T 2 value was seen, followed by a more gradual decrease. The T 2 value seemed to reach the adult level between 2 and 3 years of life in all areas examined. The T 2 values between 2 and 16 years in CC, FWM, OWM and CS were 59.7±3.6, 64.5±5.2, 69.8±4.8 and 66.3±3.3ms (mean±S.D.), respectively. The T 2 values in patients with clinically diagnosed Pelizaeus-Merzbacher disease (PMD) and late onset Krabbe disease were also calculated. In PMD, non-progressive prolongation of the T 2 value was observed in all areas. In late onset Krabbe disease, on the other hand, progressive prolongation of the T 2 values was mainly demonstrated in OWM and the posterior part of CS. These results suggest that the T 2 value in the cerebral white matter allows more objective judgement than visual inspection, and makes it possible to clarify the mechanism underlying abnormal myelination, i.e. progressive or not.

Late-Onset Krabbe Disease (Globoid Cell Leukodystrophy): Clinical and Biochemical Features of 15 Cases

The diagnosis of late-onset variants of Krabbe disease (globoid cell leukodystrophy) has been facilitated by the recognition of galactocerebrosidase deficiency as its biochemical hallmark. Fifteen patients, ages 4-73, are presented. Signs included pes cavus, optic disc pallor, progressive spastic tetraparesis, a sensorimotor demyelinating neuropathy and hypodense lesions in the parieto-occipital periventricular white matter. Although intellect was preserved in more than half the cases, significant intrafamilial variability in mental functioning was encountered in 3 families. Bone marrow transplantation was successful in 1 13-year-old girl, but caused the death of 2 teenage twin sisters.

Late Juvenlle-onset Krabbe's Disease

Krabbe's disease is an autosomal recessive leukodystrophy characterized by a lack of galactocerebroside β-galactosidase activity. In contrast to the classic early infantile-onset form of Krabbe's disease, less recognized, late-onset variants exist. The authors present a case of late juvenile-onset Krabbe's disease, including the associated magnetic resonance imaging (MRI) findings. Most patients with late-onset Krabbe's disease present with visual loss due to optic atrophy. Associated gait abnormalities and parental consanguinity should increase the clinician's suspicion that a child may have late-onset Krabbe's disease. Because of the prolonged survival in late-onset Krabbe's disease, the recent development of bone marrow transplantation for these patients makes diagnosis of this disorder particularly important.