Novel neuroimaging finding in palmitoyl protein thioesterase-1-related neuronal ceroid lipofuscinosis

Palmitoyl protein thioesterase-1 (PPT1)-related neuronal ceroid lipofuscinosis is a type of neuronal ceroid lipofuscinosis caused by a deficiency of the enzyme palmitoyl protein thioesterase-1. Cranial magnetic resonance imaging reveals more severe atrophy in the cerebral hemispheres than in the cerebellum. The basal ganglia and particularly the thalamus demonstrate low signal intensity on T(2)-weighted images from an early age. We present three patients with PPT1-related neuronal ceroid lipofuscinosis who exhibited isolated, symmetric signal changes in the bilateral dentate nucleus as sole early neuroimaging abnormality. Neither cerebral or cerebellar atrophy nor signal changes in the thalamus/basal ganglia were evident. This neuroimaging finding in PPT1-related neuronal ceroid lipofuscinosis was not previously reported.     

Juvenile-onset neuronal ceroid lipofuscinosis with infantile CLN1 mutation and palmitoyl-protein thioesterase deficiency

Accurate diagnosis, especially in progressive hereditary diseases, is essential for the treatment and genetic counseling of the patient and the family. Neuronal ceroid lipofuscinoses (NCL) are amongst the most common groups of neurodegenerative diseases. Infantile, juvenile, and adult-onset types with multiple genotype–phenotype associations have been described. A fluorimetric enzyme assay for palmitoyl protein thioesterase (PPT) from leukocytes and fibroblasts has been previously developed to confirm the diagnosis of infantile NCL. We describe a patient with juvenile-onset NCL phenotype with a new CLN1 mutation and deficient PPT activity.
Over 40 different mutations have been found in patients with PPT deficiency, indicating that screening for known mutations is not an efficient way to diagnose this disorder. Therefore, PPT enzyme analysis should precede mutation analysis in suspected PPT deficiency, particularly in patients with granular osmiophilic deposits (GROD) or in patients who have negative ultrastructural data. The use of enzyme assay led to the diagnosis of this patient with juvenile-onset Finnish variant NCL with PPT deficiency, and we expect that greater awareness of the utility of the enzymatic assay may lead to identification of other similar cases awaiting a definitive diagnosis.     

Adult neuronal ceroid lipofuscinosis with palmitoyl-protein thioesterase deficiency: first adult-onset patients of a childhood disease

The fluorogenic enzyme assay for palmitoyl-protein thioesterase (PPT) has greatly facilitated the diagnosis of infantile neuronal ceroid lipofuscinosis (Santavuori-Haltia disease) and the search for possible new variants with atypical clinical presentation. Here, we present the first cases of adult neuronal ceroid lipofuscinosis with onset in the fourth decade of life due to a profound deficiency of PPT. The causative mutations in the CLN1 gene were the known, deleterious mutation R151X and the novel missense mutation G108R. Patients presented at onset (31 and 38 years), with psychiatric symptoms only. At present (ages 56 and 54 years), visual, verbal, and cognitive losses have progressed and both patients have cerebellar ataxia and cannot walk without support.     

Adult type of neuronal ceroid lipofuscinosis.

Adult neuronal ceroid lipofuscinosis (NCL), also called Kufs' disease, is clinically distinct from the other NCLs. It is a rare condition which is difficult to diagnose. More than 50% of the reported cases of Kufs' disease are not adult NCL and correspond very likely to a heterogeneous spectrum of lipidoses. Various clinical and genetic phenotypes of adult NCL may be recognized, one featuring a progressive myoclonus epilepsy. It is important to stress that in contradistinction with the juvenile and protracted juvenile NCL, there is no pigmentary degeneration of the retina. Adult NCL is an autosomal recessive condition but two families have an autosomal dominant inheritance. The diagnosis of adult NCL may be suggested by a careful evaluation of skin, rectal or brain biopsies with the electron microscope but the diagnosis is fraught with many hazards. The pathogenetic defect lies probably in the intracellular processing of lysosomal and perhaps of Golgi membranes. The recent discovery of subunit c of mitochondrial adenosine triphosphate synthase in the stored cytosomes represents certainly an interesting prospect for future developments.     

Infantile neuronal ceroid lipofuscinosis: the first reported case in Japan diagnosed by palmitoyl-protein thioesterase enzyme activity deficiency

We herein report on a Japanese boy with infantile neuronal ceroid lipofuscinosis (INCL). He was born of incest to a girl and her maternal uncle. His development was normal at 12 months, and began to display regression at 14 months. He lost his social smile and tracking eye movement at 16 months, and could not stand and developed severe hypotonic tetraplegia at 19 months. Myoclonic movement was observed in his trunk, eye and extremities. His height, body weight and head circumstance had been normal. Both MRI and CT scans of his head showed severe cerebral, cerebellar and brainstem atrophy. The electroretinogram showed a decrease in amplitude. Enzyme studies revealed a deficiency of palmitoyl-protein thioesterase activity in his lymphocytes at 0.98 nmol/h/mg protein (control: 90.99+/-34.23). This is the first case of INCL in Japan diagnosed by enzyme activity deficiency.     

Late infantile neuronal ceroid lipofuscinosis and dopamine deficiency

Neuronal ceroid lipofuscinosis is a severe neurodegenerative lysosomal storage disorder. Gamma-aminobutyric acid and glutamate deficiency have been reported with CLN1, CLN3, and CLN6. Isolated biopterin/neopterin without dopamine deficiency has been reported in 1 patient with a CLN2 mutation. This report describes a patient with a CLN2 mutation with symptomatic biopterin and dopamine deficiency. A 4-year-old boy presented with intractable epilepsy and developmental regression starting 1 year previously. His exam showed retinopathy, scanning speech, dysmetria, and ataxic fenestrating gait with stooped posture. Electroencephalogram showed generalized spikes with occipital spikes on slow photic stimulation. Brain magnetic resonance images 1 year apart showed significant diffuse atrophy. CLN2 gene sequencing showed pathogenic compound heterozygous mutations. Cerebrospinal fluid neurotransmitters showed low homovanillic acid and tetrahydrobiopterin. Levodopa-carbidopa resulted in dramatic improvement of gait. Dopamine/biopterin deficiency is a possible secondary manifestation of CLN2 mutations. Levodopa and dopamine agonists might be useful in treating these secondary abnormalities and improving quality of life in these patients.     

Regional and cellular neuropathology in the palmitoyl protein thioesterase-1 null mutant mouse model of infantile neuronal ceroid lipofuscinosis

Infantile neuronal ceroid lipofuscinosis (INCL) is one of a group of fatal hereditary lysosomal storage disorders. Palmitoyl protein thioesterase 1 null mutant mice (PPT1-/-) now exist that accurately recapitulate many important disease features. The severely affected PPT1-/- mouse CNS exhibited reduced volume of both cortical and subcortical regions, but with sparing of the cerebellum. Pronounced differences existed in the extent of cortical thinning between different regions, due to lamina-specific effects upon neuronal survival. A dramatic reduction in cortical and hippocampal interneuron number was also evident, with different extents of specific interneuron loss depending upon the region and phenotypic marker. These neuronal changes were accompanied by widespread astrocytosis and localized microglial activation in restricted cortical and subcortical regions. This characterization of PPT1-/- mice not only provides defined pathological landmarks for understanding disease pathogenesis, but also provides an invaluable resource for subsequently judging the efficacy of therapeutic strategies.     

Equine neuronal ceroid lipofuscinosis

Neuronal ceroid lipofuscinosis (NCL) is an inherited, neurodegenerative disorder with fatal outcome in humans. It has also been described in some animal species; this is the first report of NCL in equines. Three horses showed developmental retardation, slow movements and loss of appetite at the age of six months. Neurological symptoms, as well as visual failure in one case, were noticed at the age of 1 year. Due to slowly progressing deterioration, euthanasia was indicated 1.5 years after onset of conspicuous behavior. At necropsy, slight flattening of the gyri and discoloring of the brain was noticed. Histopathology revealed eosinophilic, autofluorescent material in the perikarya of neurons throughout the brain and spinal cord. Identical material was found in neurons of retina, submucous and myenteric ganglia, as well as in glial cells. Immunohistochemistry, using antiserum against subunit c of mitochondrial ATP synthase, showed positive signals in neurons and glial cells. Electron microscopical studies revealed fingerprint profiles mixed with rectilinear structures in markedly enlarged lysosomes of neurons and renal tubules, and rectilinear structures mixed with curvilinear bodies in macrophages and lymphocytes of lymph nodes. Thus, our study presents the first occurrence of lysosomal storage disease in horses, further characterized by immunohistochemical and electron microscopical investigations as NCL.     

Adult-onset neuronal ceroid lipofuscinosis

Neuronal ceroid lipofuscinoses are a heterogenous group of genetic progressive neurodegenerative disorders. Curative therapeutic strategies are not known. These are largely diseases of childhood; adult-onset forms are rare and poorly characterized. The classical adult variant is CLN4 (Kufs' disease), in which autosomal-recessive and autosomal dominant forms are known. Furthermore the "classic infantile" CLN1, caused by a deficiency of the enzyme palmitoylprotein-thioesterase, may be of adult onset Neuronal ceroid lipofuscinoses in adulthood are multifaceted diseases. Their clinical picture is mainly characterized by progressive dementia, seizures, and extrapyramidal motor symptoms. In contrast to the infantile forms, visual loss is an uncommon feature that appears only in adult CLN1 but not CLN4, which may be helpful in clinical differential diagnosis.     

MRI in neuronal ceroid lipofuscinosis

Magnetic resonance imaging in neuronal ceroid lipofuscinosis (NCL) demonstrates cerebral and cerebellar atrophy, T2-hyperintensity of the lobar white matter and thinning of the cerebral cortex. The association of these findings, although non specific, can be observed in all the different forms of NCL, narrows the differential diagnosis of the infantile progressive encephalopathies and may suggest the diagnosis.     

Structural basis of neuronal ceroid lipofuscinosis 1

To elucidate the basis of neuronal ceroid lipofuscinosis 1 (CLN1) from the viewpoint of enzyme structure, we constructed structural models of mutant palmitoyl protein thioesterase 1 (PPT1) proteins using molecular modeling software, jackal and TINKER. We classified the amino acid substitutions responsible for CLN1 and divided them into two groups, groups 1 and 2, based on the biochemical phenotype. Then, we examined the structural changes in the PPT1 protein for each group by calculating the solvent-accessible surface area (ASA) and the number of atoms affected. Our results revealed that the structural changes in group 1, which exhibits a complete deficiency of PPT1 activity, were generally large and located in the core region of the enzyme molecule. In group 2 exhibiting residual PPT1 activity, the structural changes in PPT1 were smaller and localized near the surface of the enzyme molecule. Coloring of affected atoms based on the distances between those in the wild type and mutants revealed the characteristic structural changes in the PPT1 protein geographically and semi-quantitatively. Structural investigation provides us with a deeper insight into the basis of CLN1.     

Blood lymphocytes in neuronal ceroid lipofuscinosis

Ultrastructural examination of white blood cells of 8 patients with neuronal ceroid lipofuscinosis showed the characteristic cytosomes, i.e. curvilinear bodies, fingerprint profiles, osmiophilic bodies, as seen in nerve cells. The reliability of this simple technique in the diagnostic work-up of this progressive neurodegenerative disorder is emphasized.

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Sommario Vengono presentati i risultati dell'indagine ultrastrutturale dei linfociti circolanti in 8 pazienti affetti da Ceroido-Lipofuscinosi Neuronale. Nel citoplasma delle cellule ematiche sono stati osservati i medesimi citosomi (corpi curvilinei, processi ad impronte digitate, corpi osmiofili), che si riscontrano nei neuroni. Vengono sottolineati i vantaggi di questa semplice metodica nell'iter diagnostico di questa encefalopatia degenerativa a carattere progressivo.

     

Evoked potentials in neuronal ceroid lipofuscinosis.

Nerve conduction, EEG, visual evoked potentials, electroretinograms and somatosensory evoked potentials were investigated in 3 children with the Bielschowsky-Jansky-type and in 1 child diagnosed as Spielmeyer-Vogt-type of neuronal ceroid lipofuscinosis. Electroretinographic responses were abolished in all of them. Electroencephalograms showed high amplitude, irregular delta-theta activity and spike- or polyspike-wave discharges without localized preponderance. As a characteristic feature for the Bielschowsky-Jansky type grossly enlarged evoked responses to single light flashes were recorded. Somatosensory evoked potentials were increased in amplitude in 2 patients. Myoclonic jerks of the pyramidal type could be elicited by electrical stimuli to the median nerve. The possibility to differentiate certain neurometabolic disorders of childhood by simple electrophysiological parameters is discussed.     

CSF insulin-like growth factor-1 in infantile neuronal ceroid lipofuscinosis

BACKGROUND: Infantile neuronal ceroid lipofuscinosis (INCL) is a progressive encephalopathy in which the patients are severely disabled by the age of 3 years. It is characterized by cerebral atrophy, selective loss of cortical neurons, and secondary loss of axons and myelin sheaths of the white matter. INCL has been shown to result from a palmitoyl protein thioesterase deficiency. The authors suggested that insulin-like growth hormones and apoptosis might play a role in the pathogenesis of INCL. METHODS: The authors measured insulin-like growth factor-1 (IGF-1) and IGF binding protein 3 (IGFBP-3) in the CSF of patients with INCL by radioimmunoassay at an early stage when myelin was starting to diminish. RESULTS: The authors found low CSF IGF-1 but normal IGFBP-3 in patients with INCL compared with control subjects. Also, they observed apoptotic cell death in biopsies of INCL patients. CONCLUSIONS: Because the IGF system seems to be important for early brain development, myelination, and neuroprotection, the authors suggest that the pathology in INCL may be associated with low CSF IGF-1.     

Familial occurrence of adult-type neuronal ceroid lipofuscinosis

The adult type of neuronal ceroid lipofuscinosis (NCL) occurred in a 49-year-old man and his 51-year-old sister. They showed episodic stuporous and psychotic states, mental retardation, generalized convulsions, and ichthyosis vulgaris. At autopsy the woman had excessive accumulation of lipofuscin throughout the CNS. The degree of neuronal lipopigment accumulation was very severe in the neurons of the thalamus, substantia nigra, inferior olivary nuclei, motor nuclei of the brain stem, and cerebral cortex. Mental symptoms, such as stupor, excitement, hallucinations, and delusions, were the predominant clinical manifestations and so were misdiagnosed as schizophrenia. Though the clinical diagnosis of the adult type of NCL (Kufs' disease) is difficult because of its wide variety of manifestations, symptoms such as episodic psychotic and stuporous states accompanied by convulsive disorders with mild neurologic signs may be an indication of this disease.     

Identification and characterization of Caenorhabditis elegans palmitoyl protein thioesterase1

Infantile neuronal ceroid lipofuscinosis (INCL; Batten disease) is a severe neurodegenerative disorder of childhood characterized by the accumulation of autofluorescent storage material in lysosomes. It is caused by mutation of the CLN1/PPT1 gene, which encodes the lysosomal enzyme palmitoyl protein thioesterase-1 (PPT1), but the mechanism of disease pathogenesis and substrates for the enzyme are unknown. Caenorhabditis elegans is a simple nematode worm, with a fully sequenced genome, which is easy to maintain and manipulate. It has a completely mapped cell lineage and nervous system and has already provided clues about the pathogenesis of several human neuronal and lysosomal storage disorders. We have identified and characterized a PPT1 homologue in C. elegans. We found that, although this gene was not essential for the animal's survival, its mutation resulted in a mild developmental and reproductive phenotype, affected the number and size of mitochondria, and resulted in an abnormality in mitochondrial morphology, possibly suggestive of a role for this organelle in INCL pathogenesis. This strain, deleted for ppt-1, potentially provides a model system for the study of PPT1 and the pathogenesis of INCL.