Infantile neuronal ceroid lipofuscinosis: follow-up on a Spanish series

Management of CLN1 Disease: International Clinical Consensus

BACKGROUND

CLN1 disease (neuronal ceroid lipofuscinosis type 1) is a rare, genetic, neurodegenerative lysosomal storage disorder caused by palmitoyl-protein thioesterase 1 (PPT1) enzyme deficiency. Clinical features include developmental delay, psychomotor regression, seizures, ataxia, movement disorders, visual impairment, and early death. In general, the later the age at symptom onset, the more protracted the disease course. We sought to evaluate current evidence and to develop expert practice consensus to support clinicians who have not previously encountered patients with this rare disease.

METHODS

We searched the literature for guidelines and evidence to support clinical practice recommendations. We surveyed CLN1 disease experts and caregivers regarding their experiences and recommendations, and a meeting of experts was conducted to ascertain points of consensus and clinical practice differences.

RESULTS

We found a limited evidence base for treatment and no clinical management guidelines specific to CLN1 disease. Fifteen CLN1 disease experts and 39 caregivers responded to the surveys, and 14 experts met to develop consensus-based recommendations. The resulting management recommendations are uniquely informed by family perspectives, due to the inclusion of caregiver and advocate perspectives. A family-centered approach is supported, and individualized, multidisciplinary care is emphasized in the recommendations. Ascertainment of the specific CLN1 disease phenotype (infantile-, late infantile-, juvenile-, or adult-onset) is of key importance in informing the anticipated clinical course, prognosis, and care needs. Goals and strategies should be periodically reevaluated and adapted to patients' current needs, with a primary aim of optimizing patient and family quality of life.

Ocular Manifestations of Neuronal Ceroid Lipofuscinoses

Neuronal ceroid lipofuscinoses (NCLs) are a group of rare neurodegenerative storage disorders associated with devastating visual prognosis, with an incidence of 1/1,000,000 in the United States and comparatively higher incidence in European countries. The pathophysiological mechanisms causing NCLs occur due to enzymatic or transmembrane defects in various sub-cellular organelles including lysosomes, endoplasmic reticulum, and cytoplasmic vesicles. NCLs are categorized into different types depending upon the underlying cause i.e., soluble lysosomal enzyme deficiencies or non-enzymatic deficiencies (functions of identified proteins), which are sub-divided based on an axial classification system. In this review, we have evaluated the current evidence in the literature and reported the incidence rates, underlying mechanisms and currently available management protocols for these rare set of neuroophthalmological disorders. Additionally, we also highlighted the potential therapies under development that can expand the treatment of these rare disorders beyond symptomatic relief.

Autism, Epilepsy, and Neuroregression: Photosensitivity on Electroencephalography Solved the Riddle

Autistic epileptiform regression is an uncommon but extensively described malady in children. The clinico-etiological spectrum of this entity ranges from electrical status epilepticus in sleep to various neurogenetic and neurodegenerative disorders. Identification of these disorders is crucial considering their therapeutic and prognostic implications. Simple investigations such as neuroimaging and electroencephalography with activation procedures can provide valuable diagnostic clues in resource-limited settings; facilitating targeted genetic/metabolic testing. Here we report a 3.5-year-old girl with autistic regression and epilepsy. Neuronal ceroid lipofuscinosis was suspected as her electroencephalogram showed photoparoxysmal response on low-frequency (1-3 Hz) intermittent photic stimulation. A deficient leukocyte tripeptidyl peptidase 1 enzyme confirmed the diagnosis of late infantile neuronal ceroid lipofuscinosis.

Setup and Validation of a Targeted Next-Generation Sequencing Approach for the Diagnosis of Lysosomal Storage Disorders

Lysosomal storage disorders (LSDs) are monogenic diseases, due to accumulation of specific undegraded substrates into lysosomes. LSD diagnosis could take several years because of both poor knowledge of these diseases and shared clinical features. The diagnostic approach includes clinical evaluations, biochemical tests, and genetic analysis of the suspected gene. In this study, we evaluated an LSD targeted sequencing panel as a tool capable to potentially reverse this classic diagnostic route. The panel includes 50 LSD genes and 230 intronic sequences conserved among 33 placental mammals. For the validation phase, 56 positive controls, 13 biochemically diagnosed patients, and nine undiagnosed patients were analyzed. Disease-causing variants were identified in 66% of the positive control alleles and in 62% of the biochemically diagnosed patients. Three undiagnosed patients were diagnosed. Eight patients undiagnosed by the panel were analyzed by whole exome sequencing: for two of them, the disease-causing variants were identified. Five patients, undiagnosed by both panel and exome analyses, were investigated through array comparative genomic hybridization: one of them was diagnosed. Conserved intronic fragment analysis, performed in cases unresolved by the first-level analysis, evidenced no candidate intronic variants. Targeted sequencing has low sequencing costs and short sequencing time. However, a coverage >60× to 80× must be ensured and/or Sanger validation should be performed. Moreover, it must be supported by a thorough clinical phenotyping.

Overview of advances in educational and social supports for young persons with NCL disorders

Vision loss, dementia, and motor and speech declines all impact the educational experience of individuals with Batten disease and can adversely impact effective learning. There are as yet limited data to support evidence-based approaches to meeting the educational needs of affected individuals. This paper provides an overview of recent work to evaluate and address educational issues with a life-long perspective relevant to individuals with juvenile-onset neuronal ceroid lipofuscinosis (JNCL) and the professionals that provide them with educational support. In particular, several main activities of the recently completed 'JNCL and Education' project are summarised, including a survey of parents, educational professionals and social/health workers, development of a formative assessment tool to identify and respond to an individual student's strengths and needs in the learning environment, and proposed strategies for prolonging literacy and language skills. A key concept that should be emphasised in the educational plan for students with JNCL is that of 'proactive' and 'hastened' learning, that is, providing an early emphasis on adaptive skills that will be required in the later stages of disease progression when new learning will be more difficult to achieve. An additional key concept is participation in real-life activities to maintain skills and quality of life, particularly in the later stages of disease progression.

PPT1 Promotes Tumor Growth and Is the Molecular Target of Chloroquine Derivatives in Cancer

Clinical trials repurposing lysosomotropic chloroquine (CQ) derivatives as autophagy inhibitors in cancer demonstrate encouraging results, but the underlying mechanism of action remains unknown. Here, we report a novel dimeric CQ (DC661) capable of deacidifying the lysosome and inhibiting autophagy significantly better than hydroxychloroquine (HCQ). Using an in situ photoaffinity pulldown strategy, we identified palmitoyl-protein thioesterase 1 (PPT1) as a molecular target shared across monomeric and dimeric CQ derivatives. HCQ and Lys05 also bound to and inhibited PPT1 activity, but only DC661 maintained activity in acidic media. Knockout of PPT1 in cancer cells using CRISPR/Cas9 editing abrogates autophagy modulation and cytotoxicity of CQ derivatives, and results in significant impairment of tumor growth similar to that observed with DC661. Elevated expression of PPT1 in tumors correlates with poor survival in patients in a variety of cancers. Thus, PPT1 represents a new target in cancer that can be inhibited with CQ derivatives. SIGNIFICANCE: This study identifies PPT1 as the previously unknown lysosomal molecular target of monomeric and dimeric CQ derivatives. Genetic suppression of PPT1 impairs tumor growth, and PPT1 levels are elevated in cancer and associated with poor survival. These findings provide a strong rationale for targeting PPT1 in cancer. This article is highlighted in the In This Issue feature, p. 151.

Standardized assessment of seizures in patients with juvenile neuronal ceroid lipofuscinosis

AIM

To evaluate seizure phenomenology, treatment, and course in individuals with juvenile neuronal ceroid lipofuscinosis (JNCL).

METHOD

Data from an ongoing natural history study of JNCL were analyzed using cross-sectional and longitudinal methods. Seizures were evaluated with the Unified Batten Disease Rating Scale, a disease-specific quantitative assessment tool.

RESULTS

Eighty-six children (44 males, 42 females) with JNCL were assessed at an average of three annual visits (range 1-11). Eighty-six percent (n=74) experienced at least one seizure, most commonly generalized tonic-clonic, with mean age at onset of 9 years 7 months (SD 2y 10mo). Seizures were infrequent, typically occurring less often than once every 3 months, and were managed with one to two medications for most participants. Valproate (49%, n=36) and levetiracetam (41%, n=30) were the most commonly used seizure medications. Myoclonic seizures occurred infrequently (16%, n=14). Seizure severity did not vary by sex or genotype. Seizures showed mild worsening with increasing age.

INTERPRETATION

The neuronal ceroid lipofuscinoses (NCLs) represent a group of disorders unified by neurodegeneration and symptoms of blindness, seizures, motor impairment, and dementia. While NCLs are considered in the differential diagnosis of progressive myoclonus epilepsy, we show that myoclonic seizures are infrequent in JNCL. This highlights the NCLs as consisting of genetically distinct disorders with differing natural history.